CN1989675B - Method and system for battery charging - Google Patents

Abstract

A combination includes a battery pack and a battery charger operable to supply a charging current to the battery pack. The battery pack includes a plurality of battery cells having Li-based chemical components and a present state of charge. The battery pack also includes a battery microcontroller operable to measure the present state of charge of at least one battery cell to produce battery cell present state of charge measurements. The battery charger includes a charger microcontroller operable to receive the battery cell present state of charge measurements from the battery microcontroller. The charger microcontroller is also operable to supply the charging current to the battery pack in pulses, wherein each pulse includes a first time interval where charging current is being supplied to the battery and a second time interval where charging current is being suspended from the battery.

Description

Method and system for charging a battery

related application

The current patent application claims the benefit of the following previously filed co-pending U.S. Provisional Patent Applications: No. 60/574278, filed May 24, 2004; No. 60/574616, filed May 25, 2004; No. 60/582138 filed June 22; No. 60/582728 filed June 24, 2004; No. 60/582730 filed June 24, 2004; No. 60/582730 filed June 22, 2004 60/612352; 60/626013 filed November 5, 2004; 60/626230 filed November 9, 2004; and 60/643396 filed January 12, 2005, these patent applications The entire content of is hereby incorporated by reference.

This application is also related to U.S. Patent Application No. 10/720027, filed November 20, 2003, which claims the benefit of the earlier co-pending U.S. Provisional Patent Application: No. .60/428358; No. 60/428450 filed November 22, 2002; No. 60/428452 filed November 22, 2002; No. 60/440692 filed January 17, 2003; 60/440693, filed November 17; 60/523716, filed November 19, 2003; 60/523712, filed November 19, 2003, the entire contents of which are hereby incorporated by reference as refer to.

This application is also related to U.S. Patent Application No. 10/719,680, filed November 20, 2003, which claims the benefit of the earlier co-pending U.S. Provisional Patent Application: No. .60/428358; No. 60/428450 filed November 22, 2002; No. 60/428452 filed November 22, 2002; No. 60/440692 filed January 17, 2003; 60/440693, filed November 17; 60/523716, filed November 19, 2003; 60/523712, filed November 19, 2003, the entire contents of which are hereby incorporated by reference as refer to.

This patent application is also related to U.S. Patent Application No. 10/721,800, filed November 24, 2003, which claims the benefit of the earlier co-pending U.S. Provisional Patent Application filed on November 22, 2002 No. 60/428356; No. 60/428358 filed November 22, 2002; No. 60/428450 filed November 22, 2002; No. 60/428452 filed November 22, 2002; 2003 No. 60/440692 filed January 17; No. 60/440693 filed January 17, 2003; No. 60/523712 filed November 19, 2003; No. 60/523712 filed November 19, 2003 60/523,716, the entire contents of which patent applications are hereby incorporated by reference.

technical field

The present application relates generally to methods and systems for charging batteries, and more particularly, to methods and systems for charging power tool batteries.

Background technique

Cordless power tools are often powered by portable battery packs. These battery packs come in a wide variety of battery chemistries and nominal voltages, and can be used to power many tools and electrical devices. Typically, the battery chemistry of power tool batteries is nickel-cadmium ("NiCd") or nickel-metal hydride ("NiMH"). The nominal voltage of the battery pack is typically about 2.4V to about 24V.

Contents of the invention

Some battery chemistries, such as lithium ("Li"), lithium-ion ("Li-ion"), and other lithium-based chemistries, require precise charging schemes and operation of charge and controlled discharge. Inadequate charging schemes and uncontrolled discharging schemes can produce excessive heat buildup, excessive overcharge conditions and/or excessive overdischarge conditions. These conditions and accumulations can cause irreversible damage to the battery and can seriously affect battery capacity.

The present invention provides systems and methods for charging batteries. In some constructions and in some aspects, the present invention provides a battery charger capable of fully charging a variety of battery packs having different battery chemistries. In some constructions and in some aspects, the present invention provides a battery charger capable of fully charging lithium-based batteries, such as lithium-cobalt batteries, lithium-manganese batteries, and spinel batteries. In some constructions and in some aspects, the present invention provides a battery charger capable of charging lithium-based chemistry batteries having different nominal voltages or in different nominal voltage ranges. In some constructions and in some aspects, the present invention provides a battery charger having various charging modules implemented according to different battery conditions. In some constructions and in some aspects, the present invention provides methods and systems for charging lithium-based batteries by applying constant voltage pulses. The time between these pulses and the pulse length can be increased or decreased by the battery charger according to specific battery characteristics.

In one configuration, the present invention provides a combination comprising a battery pack and a battery charger that can be used to provide charging current to the battery pack. The battery pack includes a first battery terminal, a second battery terminal and a battery cell having a current state of charge. The battery cell is connected to at least one of the first battery terminal and the second battery terminal. The battery pack also includes a battery microcontroller coupled to at least one of the first battery terminal and the second battery terminal. The microcontroller can be used to measure the current state of charge of the battery cell to generate a current state of charge measurement of the battery cell. The battery charger includes: a first charger terminal configured to be connected to at least one of the first battery terminal and a second battery terminal; and a second charger terminal configured to be connected to at least one of the first battery terminal and the second battery terminal. Charger terminal. The first charger terminal is configured to provide charging current to the battery pack. The battery charger also includes a charger microcontroller coupled to the second charger terminal and operable to receive a current state-of-charge measurement of the battery cells from the battery microcontroller. The charger microcontroller can also be used to provide charging current to the battery pack in pulses, where each pulse includes: a first time interval in which charging current is being provided to the battery; and a second time interval in which charging the battery is paused current. The microcontroller is also operable to vary the first time interval of the pulses based at least in part on a measurement of the battery cell's current state of charge received from the battery microcontroller.

In another construction, the invention provides a method of pulse charging a battery having a plurality of cells. The method includes: measuring the state of charge of each battery cell in a plurality of battery cells; and applying a first pulse of charging current to the battery, the first pulse having: a first time interval in which the charging current is supplied to the battery; and a second The time interval in which charging current to the battery is suspended. The method also includes providing a second pulse of charging current to the battery. The second pulse has a third time interval in which charging current is provided to the battery, and a fourth time interval in which charging current to the battery is suspended. The third time interval is based at least in part on the state of charge of the battery cells, and the third time interval is less than the first time interval.

In another construction, the present invention provides a battery charger operable to provide charging current to a battery pack having cells at a current state of charge and provides a battery charger operable to measure the current state of charge of the cells microcontroller. The battery charger includes a charger microcontroller operable to receive the current state of charge of the battery cells from the battery microcontroller. The charger microcontroller is also operable to provide charging current to the battery pack in pulses, where each pulse includes a first time interval and a second time interval. The first time interval is an interval for supplying charging current to the battery, and the second time interval is an interval for suspending supplying charging current to the battery. The microcontroller is also operable to vary the first time interval of the pulses based at least in part on the current state of charge of the battery cells received from the battery microcontroller.

The unique features and unique advantages of the present invention will become apparent to those of ordinary skill in the art from the following detailed description, claims and drawings.

Description of drawings

Figure 1 is a perspective view of a battery.

FIG. 2 is another perspective view of a battery, such as that shown in FIG. 1 .

3 is a perspective view of a battery, such as the battery shown in FIG. 1 , in physical and electrical connection with a battery charger.

4 is a schematic diagram of a battery, such as the battery shown in FIG. 3, and the battery charger, electrically connected to a battery charger.

5a and 5b are flowcharts showing the operation of a battery charger, such as that shown in FIG. 3, embodying aspects of the present invention.

FIG. 6 is a flowchart showing a first module that can be implemented on a battery charger embodying aspects of the present invention, such as the battery charger shown in FIG. 3 .

FIG. 7 is a flow diagram showing a second module that can be implemented on a battery charger embodying aspects of the present invention, such as the battery charger shown in FIG. 3 .

FIG. 8 is a flowchart showing a third module that can be implemented on a battery charger embodying aspects of the present invention, such as the battery charger shown in FIG. 3 .

FIG. 9 is a flowchart showing a fourth module that can be implemented on a battery charger embodying aspects of the present invention, such as the battery charger shown in FIG. 3 .

FIG. 10 is a flowchart showing a fifth module that can be implemented on a battery charger embodying aspects of the present invention, such as the battery charger shown in FIG. 3 .

FIG. 11 is a flow diagram showing a sixth module that can be implemented on a battery charger embodying aspects of the present invention, such as the battery charger shown in FIG. 3 .

FIG. 12 is a flowchart showing a charging algorithm that can be employed on a battery charger embodying aspects of the present invention, such as the battery charger shown in FIG. 3 .

13 is a schematic diagram of a battery electrically connected to a battery charger.

14A-B are views of other configurations of batteries.

15A-B are perspective views of a battery, such as one of the batteries shown in FIGS. 1 , 2 and 14A-B, in physical and electrical connection with a power tool.

FIG. 16 is a schematic diagram of the charging current of the battery.

Figure 17 is another schematic diagram of a battery.

Figure 18 is a perspective view of a power converter connected to a battery charger.

19 is a plan view of a power converter, such as the power converter of FIG. 18, connected to a battery charger.

20 is a side view of a power converter, such as the power converter of FIG. 18, connected to a battery charger.

21 is a top view of a power converter, such as the power converter of FIG. 18, connected to a battery charger.

22 is another side view of a power converter, such as the power converter of FIG. 18, connected to a battery charger.

23 is a rear view of a power converter, such as the power converter of FIG. 18, connected to a battery charger.

24 is another perspective view of a power converter, such as the power converter of FIG. 18, connected to a battery charger.

25 is yet another perspective view of a power converter, such as the power converter of FIG. 18, connected to a battery charger.

26 is yet another perspective view of a power converter, such as the power converter of FIG. 18, connected to a battery charger.

27 is yet another perspective view of a power converter, such as the power converter of FIG. 18, connected to a battery charger.

Fig. 28 is a flowchart showing the modules of the charging operation of the battery.

Figures 29 and 30 are flowcharts showing another module of the battery charging operation.

Fig. 31 is a flowchart showing yet another block of the battery charging operation.

Fig. 32 is a flowchart showing yet another module of the battery charging operation.

Fig. 33 is a flowchart showing yet another module of the battery charging operation.

Fig. 34 is a flowchart showing yet another module of the battery charging operation.

Fig. 35 is a flowchart showing yet another block of the battery charging operation.

Fig. 36 is a flowchart showing yet another module of the battery charging operation.

37 and 38 are flowcharts showing yet another module of the battery charging operation.

Fig. 39 is a schematic diagram of the charging current of the battery.

Before describing any embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts set forth in the following description or shown in the following drawings. The invention is capable of other embodiments or of being practiced or carried out in various ways. Also, it is to be understood that the phrases and terminology used herein are for the purpose of description and should not be regarded as limiting. "Includes", "comprises" or "has" and variations thereof as used herein is meant to cover the items listed below and their equivalents as well as other items.

Detailed ways

A battery pack or battery 20 is shown in FIGS. 1 and 2 . The battery 20 is configured to power and receive energy from one or more electrical devices, such as a power tool 25 (shown in FIGS. 15A-B ) and/or a battery charger 30 (shown in FIGS. 3 and 4 ). . In some constructions and in some aspects, the battery 20 can be of any battery chemistry, such as lead-acid, nickel-cadmium (“NiCd”), nickel-metal hydride (“NiMH”), lithium (“Li”) , lithium ions ("Li ions"), another lithium-based chemistry, or another rechargeable battery chemistry. In some constructions and in some aspects, the battery 20 can provide a high discharge current to an electrical device, such as a power tool with a high current discharge rate. In the illustrated configuration, battery 20 has a Li, Li-ion battery chemistry, or another Li-based chemistry, and provides an average discharge current equal to or greater than about 2OA. For example, in the configuration shown, battery 20 can have lithium-cobalt ("Li-Co"), lithium-manganese ("Li-Mn") spinel, or Li-Mn nickel chemistry.

In some constructions and in some aspects, battery 20 may also have any nominal voltage, such as a nominal voltage of about 9.6V to about 50V. In one configuration (see FIGS. 1-3 ), for example, battery 20 has a nominal voltage of approximately 21V. In another configuration (see FIG. 14), the battery 20A has a nominal voltage of approximately 28V. It should be understood that in other configurations, battery 20 may have another nominal voltage within another nominal voltage range.

The battery 20 includes a housing 35 provided with a terminal support 40 . The battery 20 also includes one or more battery terminals supported by the terminal support 40 and connectable to electrical devices such as the power tool 25 and/or the battery charger 30 . In some constructions, such as that shown in FIG. 4 , the battery 20 includes a positive battery terminal 45 , a negative battery terminal 50 , and a sense battery terminal 55 . In some configurations, battery 20 includes more or fewer terminals than in the configurations shown.

Battery 20 includes one or more battery cells 60, each having a chemical composition and a nominal voltage. In some constructions, battery 20 has a Li-ion battery chemistry, a nominal voltage of approximately 18V or 21V, and includes five battery cells. In some constructions, each battery cell 60 has a Li ion chemistry, and each battery cell 60 has substantially the same nominal voltage, eg, about 3.6V or about 4.2V.

In some constructions and in some aspects, battery 20 includes identification circuitry or components electrically connected to one or more battery terminals. In some constructions, an electrical device, such as battery charger 30 (shown in FIGS. 3 and 4 ), "reads" or receives input from an identification circuit or component in order to determine one or more battery feature. In some constructions, the battery characteristics may include, for example, the nominal voltage of the battery 20 , the temperature of the battery 20 , and/or the chemical composition of the battery 20 .

In some constructions and in some aspects, battery 20 includes a control device, microcontroller, microprocessor, or controller electrically connected to one or more battery terminals. The controller communicates with an electrical device, such as the battery charger 30, and provides the device with information about one or more battery characteristics or conditions, such as the nominal voltage of the battery 20, individual cell voltages, the temperature of the battery 20, and the battery 20 chemical components. In some constructions, such as that shown in FIG. 4 , the battery 20 includes an identification circuit 62 with a microprocessor or controller 64 .

In some constructions and in some aspects, battery 20 includes a temperature sensing device or thermistor. The thermistor is constructed and disposed within the battery 20 to detect the temperature of one or more battery cells or the temperature of the entire battery 20 . In some constructions, such as that shown in FIG. 4 , the battery 20 includes a thermistor 66 . In the illustrated construction, a thermistor 66 is included in the identification circuit 62 .

As shown in FIGS. 3 and 4 , the battery 20 is also configured to be connected to an electrical device, such as a battery charger 30 . In some constructions, battery charger 30 includes housing 70 . The case 70 is provided with a connection portion 75 to which the battery 20 is connected. Connection portion 75 includes one or more electrical device terminals for electrically connecting battery 20 to battery charger 30 . These terminals included in the battery charger 30 are configured to cooperate with terminals included in the battery 20 and transmit and receive energy and information from the battery 20 .

In some constructions, such as that shown in FIG. 4 , the battery charger 30 includes a positive terminal 80 , a negative terminal 85 and a sense terminal 90 . In some constructions, the positive terminal 80 of the battery charger 30 is configured to mate with the positive battery terminal 45 . In some constructions, the negative terminal 85 and the test terminal 90 of the battery charger 30 are configured to mate with the negative battery terminal 50 and the test battery terminal 55, respectively.

In some constructions and in some aspects, the battery charger 30 also includes a charging circuit 95 . In some constructions, charging circuit 95 includes a control device, microcontroller, microprocessor or controller 100 . The controller 100 controls the energy transfer between the battery 20 and the battery charger 30 . In some constructions, the controller 100 controls the transfer of information between the battery 20 and the battery charger 30 . In some constructions, the controller 100 identifies and/or determines one or more characteristics or conditions of the battery 20 based on signals received from the battery 20 . Also, the controller 100 can control the operation of the charger 30 according to the identification feature of the battery 20 .

In some constructions and in some aspects, controller 100 includes various timers, backup timers and counters, and/or is capable of various timing and counting functions. The timers, backup timers and counters are used and controlled by the controller 100 during the various charging steps and/or modules. Timers, backup timers, and counters are described below.

In some constructions and in some aspects, battery charger 30 includes a display or indicator 110 . Indicator 110 informs the user of the status of battery charger 30 . In some constructions, the indicator 110 can inform the user of the different charging stages, charging modes, or charging modules that are beginning and/or completing during operation. In some constructions, the indicator 110 includes a first light emitting diode (“LED”) 115 and a second LED 120 . In the structure shown, the first and second LEDs 115 and 120 are LEDs of different colors. For example, the first LED 115 is a red LED and the second LED 120 is a green LED. In some constructions, the controller 100 enables and controls the indicator 110 . In some constructions, the indicator 110 is disposed on, or included in, the housing 70 such that the indicator 110 is visible to the user. The display may also include indicators to show the percentage of charge, remaining time, etc. In some constructions, the display or indicator 110 may include a fuel gauge provided on the battery 20 .

The battery charger 30 is adapted to receive an energy input from a power source 130 . In some constructions, the power source 130 is approximately a 120V AC, 60Hz signal. In other constructions, the power supply 130 is approximately a 240V AC signal. In other configurations, the power source 130 is, for example, a constant current source. In these configurations, the power supply 130 can include a 12V DC signal, such as a DC signal received from a car outlet (eg, from a car battery).

In the illustrated construction, the battery charger 30 receives power input from an AC power source. To use DC power, the user may connect the battery charger 30 to the power converter 2140 shown in FIGS. 18-27. In these configurations, the power converter 2140 converts a first signal, such as a DC signal (eg, a 12V DC signal from a DC outlet of an automobile) to a second signal, such as an AC signal (eg, a 120V AC signal).

As shown in FIGS. 18-26 , power converter 2140 includes housing 2145 . In the illustrated construction, housing 2145 includes a first end 2146 , a second end 2147 , a first side 2148 , and a second side 2149 . Housing 2145 also includes a bottom surface 2152 and a top surface 2154 . In other constructions, the housing 2145 can include more or fewer surfaces, sides and ends than shown and described.

In one configuration, the top surface 2154 can provide an area for the battery charger 30 to be placed. In the illustrated construction, top surface 2154 has substantially the same width and length as battery charger 30 . In other constructions, the width and length of the top surface 2154 may be greater or less than the battery charger 30 . In other constructions, the top surface 2154 may include a locking mechanism (not shown) for securing the battery charger 30 to the power converter 2140 . In other constructions, another portion of the housing 2145 may include a locking mechanism for securing the battery charger 30 to the converter 2140 .

The power converter 2140 also includes an input 2159 for receiving a first power signal (ie, a DC power signal). In some constructions, the input 2159 includes a wire 2160 and an input connector 2165 . In the configuration shown, input connector 2165 includes a 12-V DC input plug for receiving a DC signal from the vehicle's DC outlet.

The power converter 2140 also includes a converted output 2170 for delivering a second power signal (ie, an AC power signal). In the illustrated construction, the switched output 2170 includes an AC outlet, such as a three-wire straight blade outlet 2170 . As shown in FIG. 18 , an outlet 2170 is provided on the electric wire roll 2155 .

In some constructions, power converter 2140 may include coil of wire 2155 . The cord reel 2155 may store and secure the cord 2156 of the battery charger 30 . In the illustrated construction, the groove 2158 in the second end 2147 of the housing 2145 forms the coil of wire 2155 .

In some constructions, the power converter 2140 can include a second output 2180 . In the illustrated construction, a second output 2180 is disposed on the first end 2146 of the housing 2145 and can be used to deliver a second (converted) power signal. In other constructions, the output 2180 may deliver the first power signal (ie, a DC signal). In other constructions, the converter 2140 may include a further output 2180 delivering the first power signal or the second power signal. In still other configurations, converter 2140 may include a combination of second output ports 2180, at least one for delivering the first power signal and at least one other output port for delivering the second power signal.

In some constructions, the power converter 2140 may include a switch 2185 for controlling the output of power through the converter output 2170 . Switch 2185 can include: an on position, wherein converter 2140 can be used to distribute electrical energy through switching output 2170 (while converter 2140 is receiving the first power signal); and an off position, wherein converter 2140 can not be used to switch Output 2170 distributes electrical energy. The position of the switch 2185 may be indicated to the user by one or more LEDs, such as a first LED 2188 and a second LED 2189 shown in FIGS. 23-26. In the illustrated construction, a first LED 2188 and a second LED 2189 are disposed on the first end 2146 of the housing 2145 . In one configuration, the first LED 2188 is a red LED and indicates that the converter 2140 cannot be used to provide power through the switching output 2170 , while the second LED 2189 is a green LED and indicates that the converter 2140 can be powered through the switching output 2170 . In other configurations, the switch 2185 can control the output of the second output terminal 2180 . In still other configurations, the converter 2140 includes a switch 2185 for each output or port 2170 , 2180 .

In some constructions and in some aspects, battery charger 30 may charge a variety of rechargeable batteries having different battery chemistries and different nominal voltages, as described below. For example, in an exemplary embodiment, battery charger 30 may charge a first battery having a NiCd battery chemistry and a nominal voltage of approximately 14.4V, a battery having a Li-ion battery chemistry and a nominal voltage of approximately 18V, The second battery, and a third battery having a Li-ion battery chemistry and a nominal voltage of approximately 28V are charged. In another exemplary embodiment, the battery charger 30 can charge a first Li-ion battery having a nominal voltage of approximately 21V, and a second Li-ion battery having a nominal voltage of approximately 28V. In this exemplary embodiment, the battery charger 30 is able to identify the nominal voltage of each battery 20, as described below, and thereby scale the particular threshold, as described below, or based on the battery nominal voltage, Change the voltage reading or measurement (taken during charging).

In some constructions, battery charger 30 may identify the nominal voltage of battery 20 by "reading" an identification component included in battery 20, or by receiving a signal from, for example, a battery microprocessor or controller. In some constructions, the battery charger 30 may include acceptable nominal voltage ranges for the various batteries 20 that the charger 30 can recognize. In some constructions, the acceptable nominal voltage range includes a range from about 8V to about 50V. In other constructions, the acceptable nominal voltage range may include a range from about 12V to about 28V. In other constructions, the battery charger 30 is capable of recognizing nominal voltages equal to about 12V and greater. Also, in other constructions, the battery charger 30 is capable of recognizing nominal voltages equal to about 30V and lower.

In other constructions, the battery charger 30 may recognize a range of values that includes the nominal voltage of the battery 20 . For example, instead of recognizing that the first battery 20 has a voltage of about 18V, the battery charger 30 can recognize that the nominal voltage of the first battery 20 falls within a range of, for example, about 18V to about 22V or about 16V to about 24V. Q. In other constructions, battery charger 30 may also recognize other battery characteristics, such as battery cell count, battery chemistry, and the like.

In other constructions, the charger 30 can recognize any nominal voltage of the battery 20 . In these configurations, the charger 30 is capable of charging any nominal voltage battery 20 by adjusting or scaling certain thresholds according to the nominal voltage of the battery 20 . Also, in these configurations, regardless of nominal voltage, each battery 20 may receive approximately the same amount of charging current for approximately the same time (eg, with each battery 20 approximately fully discharged). The battery charger 30 may adjust or scale these thresholds (described below), or adjust or scale the measured values based on the nominal voltage of the battery 30 being charged.

For example, battery charger 30 may identify a first battery having a nominal voltage of approximately 21V and 5 cells. Throughout charging, battery charger 30 varies each measurement sampled by charger 30 (eg, battery voltage) to obtain measurements for each battery cell. That is, charger 30 divides each battery voltage measurement by 5 (eg, 5 battery cells) to obtain approximately the average voltage of the battery cells. Accordingly, all thresholds included in battery charger 30 may be associated with each battery cell measurement. Also, the battery charger 30 may recognize a second battery having a nominal voltage of approximately 28V and 7 cells. Similar to operating with the first battery, the battery charger 30 varies each voltage measurement to obtain each cell measurement. Also, all thresholds included in battery charger 30 may be associated with each battery cell measurement. In this embodiment, battery charger 30 may use the same threshold to monitor and suspend charging of the first and second batteries, thereby enabling battery charger 30 to charge many batteries over a nominal voltage range.

In some constructions and in some aspects, the battery charger 30 implements a charging scheme or method for charging the battery 20 based on the temperature of the battery 20 . In one construction, the battery charger 30 provides charging current to the battery 20 while periodically sensing or monitoring the temperature of the battery 20 . If battery 20 does not include a microprocessor or controller, battery charger 30 periodically measures the resistance of thermistor 66 after a specified period of time. If the battery 20 includes a microprocessor or controller, such as the controller 64, the battery charger 30 optionally: 1) periodically interrogates the controller 64 to determine the battery temperature and/or whether the battery temperature is within an appropriate operating range; or 2) wait to receive a signal from controller 64 indicating that the battery temperature is not within the proper operating range, as will be described below.

In some constructions and in some aspects, battery charger 30 implements a charging scheme or method for charging battery 20 based on the current voltage of battery 20 . In some constructions, the battery charges while periodically sensing or monitoring the battery voltage while current is being supplied to the battery 20, and/or after a specified period of time has elapsed when no current is being supplied, as described below. The device 30 provides charging current to the battery 20 . In some constructions, the battery charger 30 implements a charging scheme or method for charging the battery 20 based on the temperature and voltage of the battery 20 . Also, charging schemes may be based on individual battery cell voltages.

The battery charger 30 interrupts the charging current once the battery temperature and/or the battery voltage exceed specified thresholds, or do not fall within the proper operating range. The battery charger 30 continues to periodically detect or monitor the battery temperature/voltage, or wait, to receive a signal from the controller 64 indicating that the battery temperature/voltage is within the proper operating range. When the battery temperature/voltage is within the proper operating range, the battery charger 30 can resume providing charging current to the battery 20 . The battery charger 30 continues to monitor the battery temperature/voltage, and continues to interrupt and resume the charging current according to the detected battery temperature/voltage. In some constructions, battery charger 30 terminates charging when the battery capacity reaches a specified threshold, or after a specified period of time. In other constructions, charging is terminated when the battery 20 is removed from the battery charger 30 .

In some constructions and in some aspects, battery charger 30 includes methods of operation for charging various batteries, such as batteries 20 having different chemistries and/or nominal voltages. An example of this charging operation 200 is shown in Figures 5a and 5b. In some constructions and in some aspects, the battery charger 30 includes a battery for charging a Li-based battery, for example, having a Li-Co chemistry, a Li-Mn spinel chemistry, a Li-Mn nickel chemistry, etc. How to charge the battery. In some constructions and in some aspects, charging operation 200 includes various modules for performing different functions in response to different battery conditions and/or battery characteristics.

In some constructions and in some aspects, the method of operation 200 includes means for interrupting charging based on abnormal and/or normal battery conditions. In some constructions, charging operation 200 includes: a faulty battery module, such as the faulty battery module shown in flowchart 205 of FIG. The temperature out-of-range module is shown in . In some constructions, the battery charger 30 accesses the faulty battery module 205 to discontinue charging based on abnormal battery voltage, abnormal cell voltage, and/or abnormal battery capacity. In some constructions, the battery charger 30 enters the temperature out of range module 210 to suspend charging based on abnormal battery temperature and/or one or more abnormal battery cell temperatures. In some constructions, charging operation 200 includes more or fewer modules that terminate charging based on more or fewer battery conditions than those described above and below. The charging operation and other configurations of the charging module are shown in Figures 28-38.

In some constructions and in some aspects, charging operation 200 includes various modes or modules for charging battery 20 according to various battery conditions. In some constructions, charging operation 200 includes: a trickle charging module, such as that shown in flowchart 215 of FIG. 8 ; a step charging module, such as that shown in flowchart 220 of FIG. 9 A step-by-step charging module; a fast charging module, such as the fast charging module shown in the flowchart 225 of FIG. 10 ; and/or a maintenance charging module, such as the maintenance module shown in the flowchart 230 of FIG. 11 .

In some constructions and in some aspects, during charging operation 200, controller 100 selects each charging module 215-230 based on a particular battery temperature range, a particular battery voltage range, and/or a particular battery capacity range. In some constructions, the controller 100 selects each module 215-230 based on the battery characteristics shown in Table 1. In some constructions, the condition "battery temperature" or "temperature of the battery" may include: battery temperature obtained as a whole (ie, battery cells, battery components, etc.); and/or temperatures of battery cells taken individually or collectively. In some constructions, as described below, each charging module 215-230 may be based on the same basic charging scheme or algorithm, eg, full charging current.

Table 1 Operations for charging Li-based batteries

V2 to V3 Not charging. The first LED blinks slowly. Maintenance charging. The second LED is on steadily. Maintenance charging. The second LED is on steadily. Not charging. The first LED blinks slowly. ＞V3 Not charging. The first LED blinks rapidly. Not charging. The first LED blinks rapidly. Not charging. The first LED blinks rapidly. Not charging. The first LED blinks rapidly.

In some constructions and in some aspects, the charging current applied to the battery 20 during the trickle charging module 215 includes applying the full charging current (e.g., "I") to the battery 20 for a first time period, such as ten seconds, Then, all charging current is suspended for a second time period, for example fifty seconds. In some constructions, the total charge current is approximately a charge current pulse at a prescribed magnitude. In some constructions, the battery charger 30 only enters the trickle charging module 215 when the battery voltage is less than the first prescribed voltage threshold V1.

In some constructions and in some aspects, the charging current applied to the battery 20 during the fast charging module 225 includes applying the full charging current to the battery 20 for a first time period, such as 1 second, and then suspending the full charging current. The second time period is, for example, 50ms. In some constructions, the controller 100 sets the backup timer to a first specified time limit, such as approximately 2 hours. In these configurations, the battery charger 30 will not implement the fast charging module 225 within the specified time limit to avoid battery damage. In other constructions, the battery charger 30 will disconnect (eg, stop charging) upon expiration of a specified time period.

In some constructions, when the battery voltage is included in the range from the first voltage threshold V1 to the second specified voltage threshold V2, and the battery temperature falls within the range from the second battery temperature threshold T2 to the third battery temperature threshold T3 In the case of battery charger 30 only enters fast charging module 225. In some constructions, the second voltage threshold V2 is greater than the first voltage threshold V1, and the third temperature threshold T3 is greater than the second temperature threshold T2.

In some constructions and in some aspects, the charging current applied to the battery 20 during the step charging module 220 includes applying the charging current of the fast charging module 225 to the battery 20, but with a one minute charge ("on" ) with a one-minute pause in charging (“disconnect”). In some constructions, the controller 100 sets the backup timer to a second specified time period, such as approximately 4 hours. In these configurations, the battery charger 30 will not implement the step-by-step charging module 220 within the prescribed time limit in order to avoid battery damage.

In some constructions, if the battery voltage is included in the range from the first voltage threshold V1 to the second voltage threshold V2, and the battery temperature falls within the range from the first battery temperature threshold T1 to the second temperature threshold T2, the battery The charger 30 only enters the step-by-step charging module 220 . In some constructions, the second voltage threshold V2 is greater than the first voltage threshold V1 , and the second temperature threshold T2 is greater than the first temperature threshold T1 .

In some constructions and in some aspects, the charging current applied to the battery 20 during the maintenance module 230 includes applying the full charging current to the battery 20 only when the battery voltage drops below a certain specified threshold. In some constructions, the threshold is approximately 4.05-V per cell +/- 1% per cell. In some constructions, where the battery voltage is included in the range from the second voltage threshold V2 to the third prescribed voltage threshold V3, and the battery temperature falls within the range from the first temperature threshold T1 to the third temperature threshold T3 Next, the battery charger 30 only enters the maintenance module 230.

In some constructions and in some aspects, the controller 100 implements various charging modules 220-230 based on various battery conditions. In some constructions, each charging module 220-230 includes the same charging algorithm (eg, the algorithm used to apply the full charging current). However, each charging module 220-230 implements, repeats, or introduces a charging algorithm in a different manner. One example of a charging algorithm is the charging current algorithm shown in flowchart 250 of FIG. 12 , as will be described below.

As shown in Figures 5a and 5b, charging operation 200 begins at step 305 when a battery, such as battery 20, is inserted into or electrically connected to battery charger 30. At step 310 , the controller 100 determines whether a steady power input, such as the power source 130 , is applied to or connected to the battery charger 30 . As shown in FIG. 5 a , after the battery 20 is electrically connected to the battery charger 30 , with power applied, the same operation is still performed (ie, step 305 proceeds to step 310 ).

If the controller 100 determines that a steady power input is not applied, the controller 100 will not activate the indicator 110 and the battery 20 will not be charged at step 315 . In some constructions, the battery charger 30 draws a small discharge current at step 315 . In some constructions, the discharge voltage is less than about 0.1 mA.

If the controller 100 determines at step 310 that a steady power input is applied to the battery charger 30 , the operation 200 proceeds to step 320 . At step 320, the controller 100 determines whether all connections between the battery terminals 45, 50, and 55 and the battery charger terminals 80, 85, and 90 are stable. If the connections are unstable at step 320 , the controller 100 proceeds to step 315 .

If these connections are stable at step 320 , the controller 100 identifies the chemical composition of the battery 20 at step 325 via the sense terminal 55 of the battery 20 . In some constructions, the resistance sense lead from the battery 20 indicates that the battery 20 has a NiCd or NiMH chemistry, as sensed by the controller 100 . In some constructions, the controller 100 will measure the resistance of the resistance sense lead to determine the chemical composition of the battery 20 . For example, in some constructions, if the resistance of the sense lead falls within a first range, the chemical composition of battery 20 is NiCd. If the resistance of the sense lead falls within the second range, the chemical composition of the battery 20 is NiMH.

In some constructions, the battery charger 30 charges the NiCd battery and the NiMH battery using a single charging algorithm that is different than that implemented for batteries with Li-based chemistries. In some configurations, the single charging algorithm for NiCd batteries and NiMH batteries is, for example, the existing charging algorithm for NiCd/NiMH batteries. In some constructions, battery charger 30 uses a single charging algorithm for NiCd batteries and NiMH batteries, but terminates the charging process for NiCd batteries with a different termination scheme than is used to terminate charging NiMH batteries . In some constructions, battery charger 30 terminates charging the NiCd battery when controller 100 detects a negative change (eg, -ΔV) in the battery voltage. In some constructions, battery charger 30 terminates charging the NiMH battery when the change in battery temperature over time (eg, ΔT/dt) reaches or exceeds a specified termination threshold.

In some configurations, NiCd and/or NiMH batteries are charged using a constant current algorithm. For example, battery charger 30 may include the same charging circuitry for charging different batteries having different battery chemistries such as NiCd, NiMH, Li-ion, and the like. In an exemplary configuration, charger 30 may use a charging circuit to apply a constant current algorithm, instead of pulse charging, to apply the same overall charging current to NiCd and NiMH batteries as Li-ion batteries. In another exemplary configuration, the battery charger 30 is capable of scaling the overall charging current through the charging circuit based on the battery chemistry.

In other constructions, the controller 100 will not determine the exact chemical composition of the battery 20 . However, the controller 100 implements a charging module capable of efficiently charging NiCd batteries and NiMH batteries.

In other constructions, sensing the resistance of the lead may indicate that the battery 20 has a Li-based chemistry. For example, if the resistance of the sense lead falls within the third range, the chemical composition of the battery 20 is Li-based.

In some constructions, a serial communication link established between battery charger 30 and battery 20 via sense terminals 55 and 90 indicates that battery 20 has a Li-based chemistry. If a serial communication link is established at step 320 , a microprocessor or controller in battery 20 , such as controller 64 , sends information about battery 20 to controller 100 in battery charger 30 . Such information communicated between battery 20 and battery charger 30 may include battery chemistry, nominal battery voltage, battery capacity, battery temperature, individual cell voltages, number of charge cycles, number of discharge cycles, protection circuits, or network status ( For example, enable, disable, enable, etc.) etc.

At step 330, the controller 100 determines whether the chemical composition of the battery 20 is Li-based. If the controller 100 determines at step 330 that the battery 20 has a NiCd or NiMH chemistry, the operation 200 proceeds to the NiCd/NiMH charging algorithm at step 335 .

If the controller 100 determines at step 330 that the battery 20 has a Li-based chemistry, the operation 200 proceeds to step 340 . At step 340 , the controller 100 resets any battery protection circuitry included in the battery 20 , such as switches, and determines the nominal voltage of the battery 20 via the communication link. At step 345, the controller 100 sets the charger analog-to-digital converter ("A/D") to the appropriate level based on the nominal voltage.

At step 350 , the controller 100 measures the current voltage of the battery 20 . Once the measurement is taken, at step 355 the controller 100 determines whether the voltage of the battery 20 is greater than 4.3-V/cell. If the battery voltage is greater than 4.3-V/cell at step 355 , operations 200 proceed to the faulty battery module 205 at step 360 . The defective battery pack module 205 will be described below.

If the battery voltage is not greater than 4.3-V/cell at step 355 , the controller 100 measures the battery temperature at step 365 and determines whether the battery temperature is below -20°C or above 65°C at step 370 . If the battery temperature is below -20° C. or exceeds 65° C. at step 370 , the operation 200 proceeds to the temperature out of range module 210 at step 375 . The temperature out of range module 210 will be described below.

If the battery temperature does not fall below -20°C or exceeds 65°C at step 370, the controller 100 determines whether the battery temperature falls between -20°C and 0°C at step 380 (shown in Figure 5b) . If the battery temperature falls between -20° C. and 0° C. at step 380 , the operation 200 proceeds to step 385 . At step 385, the controller 100 determines whether the battery voltage is less than 3.5-V/cell. If the battery voltage is less than 3.5-V/cell, the operation 200 proceeds to the trickle charging module 215 at step 390 . The trickle charging module 215 will be described below.

If the battery voltage is not less than 3.5-V/cell at step 385 , the controller 100 determines whether the battery voltage is included in a voltage range of 3.5-V/cell to 4.1-V/cell at step 395 . If the battery voltage is not included in the 3.5-V/cell to 4.1-V/cell voltage range at step 395 , the operations 200 proceed to the maintenance module 230 at step 400 . The maintenance module 230 will be described below.

If the battery voltage is included in the voltage range of 3.5-V/cell to 4.1-V/cell at step 395 , the controller 100 clears a counter, eg, a charge counter, at step 405 . Once the charge counter is cleared at step 405 , the operation 200 proceeds to the step-by-step charge module 220 at step 410 . The step-by-step charging module 220 and the charging counter will be described below.

Returning to step 380, if the battery temperature is not included between -10°C and 0°C, the controller 100 determines at step 415 whether the battery voltage is less than 3.5V/cell. If the battery voltage is less than 3.5 V/cell at step 415 , the operation 200 proceeds to the trickle charging module 215 at step 420 .

If the battery voltage is not less than 3.5-V/cell at step 415 , the controller 100 determines whether the battery voltage is included in a voltage range of 3.5-V/cell to 4.1-V/cell at step 425 . If the battery voltage is not included in the 3.5-V/cell to 4.1-V/cell voltage range at step 425 , the operation 200 proceeds to the maintenance module 230 at step 430 .

If the battery voltage is included in the voltage range of 3.5-V/cell to 4.1-V/cell at step 425 , the controller 100 clears a counter, eg, a charge counter, at step 435 . Once the charge counter is cleared at step 435 , the operation 200 proceeds to the fast charge module 225 at step 440 . The fast charging module 225 will be described below.

FIG. 6 is a flowchart showing the operation of the faulty battery pack module 205 . Operation of the module 205 begins at step 460 when the main charging operation 200 enters the faulty battery module 205 . The controller 100 interrupts the charging current at step 465 and activates the indicator 110 , such as a first LED, at step 470 . In the configuration shown, the controller 100 controls the first LED to blink at a rate of about 4 Hz. Once indicator 110 is activated at step 470, module 205 terminates at step 475 and operations 200 end.

FIG. 7 is a flowchart showing the operation of the temperature overrange module 210 . Operation of the module 210 begins at step 490 when the main charging operation 200 enters the temperature out of range module 210 . The controller 100 interrupts the charging current at step 495 and activates the indicator 110 , such as a first LED, at step 500 . In the shown configuration, the controller 100 controls the first LED to blink at a frequency of about 1 Hz to indicate to the user that the battery charger 30 is currently in the temperature out-of-range module 210 . Once indicator 110 is activated at step 500, operation 200 leaves module 210 and proceeds to operation 200 stop.

FIG. 8 is a flowchart showing the trickle charging module 215 . Operation of the module 215 begins at step 520 when the main charging operation 200 enters the trickle charging module 215 . The controller 100 activates the indicator 110 , such as the first LED 115 at step 525 , to indicate to the user that the battery charger 30 is currently charging the battery 20 . In the configuration shown, the controller 100 activates the first LED 115 in such a way that it appears to be always on.

Once the indicator 110 is activated at step 525 , the controller 100 initializes a counter, such as a trickle charge count counter, at step 530 . In the configuration shown, the trickle charge count counter has a count limit of 20.

At step 540, the controller 100 begins applying ten one-second ("1-s") full current pulses to the battery 20, and then suspends charging for 50 seconds ("50-s"). In some configurations, there is a time interval of 50 ms between 1-s pulses.

At step 545, the controller 100 measures the battery voltage while the charging current is being applied to the battery 20 (eg, current on time) to determine whether the battery voltage exceeds 4.6-V/cell. If the battery voltage exceeds 4.6-V/cell during the current on-time at step 545 , the module 215 proceeds to the faulty battery module 205 at step 550 and will terminate at step 552 . If the battery voltage does not exceed 4.6-V/cell during the current on time at step 545, then at step 555 when no charging current is applied to the battery 20 (e.g., current off time), the controller 100 measures output battery temperature and battery voltage.

At step 560, the controller 100 determines whether the battery temperature is below -10°C or above 65°C. If the battery temperature is below -20° C. or above 65° C. at step 560 , the module 215 proceeds to the temperature out of range module 210 at step 565 and will end at step 570 . If the battery temperature is not lower than -20° C. or higher than 65° C. at step 560 , the controller 100 determines whether the battery voltage is included in the range of 3.5-V/cell to 4.1-V/cell at step 575 .

If the battery voltage is included in the range of 3.5-V/cell to 4.1-V/cell at step 575 , the controller 100 determines whether the battery temperature is included in the range of -20°C to 0°C at step 580 . If the battery temperature is included in the range of -20° C. to 0° C. at step 580 , the module 215 proceeds to the step charging module 220 at step 585 . If the battery temperature is not included in the range of -20° C. to 0° C. at step 585 , the module 215 proceeds to the fast charging module 225 at step 590 .

If the battery voltage is not included in the range of 3.5-V/cell to 4.1-V/cell at step 575 , the controller 100 increments the trickle charge count counter at step 595 . At step 600 , the controller 100 determines whether the trickle charge count counter is equal to a counter limit, eg, twenty. If the counter is not equal to the counter limit at step 600 , module 215 proceeds to step 540 . If the counter is equal to the count limit at step 600 , the module 215 proceeds to the faulty battery module 205 at step 605 and will end at step 610 .

FIG. 9 is a flowchart showing the step-by-step charging module 220 . Operation of the module 220 begins when the main charging operation 200 enters the step charging module 220 at step 630 . The controller 100 activates the indicator 110 , such as the first LED 115 at step 635 , to indicate to the user that the battery charger 30 is currently charging the battery 20 . In the configuration shown, the controller 100 activates the first LED 115 so that it appears to be always on.

At step 640, the controller 100 starts a first timer or charge-on timer. In the configuration shown, the charge on timer counts down from 1 minute. At step 645 , the module 220 proceeds to the charging current algorithm 250 . Once the charge current algorithm 250 is performed, the controller 100 determines at step 650 whether the charge count is equal to a count limit, eg, 7200. If the charge count is equal to the count limit at step 650 , then module 220 proceeds to the faulty battery module 205 at step 655 and module 220 will end at step 660 .

If the charge count is not equal to the count limit at step 650, the controller 100 determines at step 665 whether the wait time between current pulses (as will be described below) is greater than or equal to a first wait time threshold, e.g. 20 seconds. If the waiting time is greater than or equal to the first waiting time at step 665, the controller 100 activates the indicator 110 at step 670, such as turning off the first LED 115 and enabling the second LED 120 to blink at a frequency of about 1 Hz. If the latency is greater than or equal to the first latency threshold at step 665, module 220 proceeds to step 690 described below.

Once the indicator 110 is activated at step 670, the controller 100 determines at step 675 whether the waiting time between current pulses is greater than or equal to a second waiting time threshold, eg, 50 seconds. If the waiting time is greater than or equal to the second waiting time threshold at step 675, the controller 100 changes the indicator 110 at step 680, for example activating the second LED 120 so that the second LED 120 appears to be always on. Module 220 then proceeds to maintenance module 230 at step 685 .

If the wait time is not greater than or equal to the second wait time threshold at step 675 , the controller 100 determines whether the battery temperature is greater than 0° C. at step 690 . If the battery temperature is greater than 0° C. at step 690 , the module 220 proceeds to the fast charging module 225 at step 695 . If the battery temperature is not greater than 0° C. at step 690 , the controller 100 determines whether the charge-on timer has expired at step 700 .

If the charge on timer has not expired at step 700 , module 220 proceeds to charge current algorithm 250 at step 645 . If the charge-on timer has expired at step 700 , the controller 100 starts a second timer or a charge-off timer at step 705 and discontinues charging. At step 710, the controller 100 determines whether the charge disconnect timer has expired. If the charge disconnect timer has not expired at step 710 , the controller 100 waits for a specified time at step 715 and then returns to step 710 . If the charge off timer has expired at step 710, the module 220 returns to step 640 to restart the charge on timer.

FIG. 10 is a flowchart showing the fast charging module 225 . Operation of the module 225 begins at step 730 when the main charging operation 200 enters the fast charging module 225 . The controller 100 activates the indicator 110 , such as the first LED 115 at step 735 , to indicate to the user that the battery charger 30 is currently charging the battery 20 . In the configuration shown, the controller 100 activates the first LED 115 in such a way that it appears to be always on.

At step 740 , the module 225 proceeds to the charging current algorithm 250 . Once the charge current algorithm 250 is performed, the controller 100 determines at step 745 if the charge count is equal to the count limit (eg, 7200). If the charge count is equal to the count limit at step 745 , then module 220 proceeds to the faulty battery module 205 at step 750 and module 220 will end at step 755 .

If the charge count is not equal to the count limit at step 745 , the controller 100 determines whether the wait time between current pulses is greater than or equal to a first wait time threshold (eg, two seconds) at step 760 . If the wait time is greater than or equal to the first wait time threshold at step 765, the controller 100 activates the indicator 110 at step 765, eg, turns off the first LED 115 and activates the second LED 120 to blink at a frequency of about 1 Hz. If at step 760 the latency is not greater than or equal to the first latency threshold, module 225 proceeds to step 785 described below.

Once the indicator 110 is activated at step 765, the controller 100 determines at step 770 whether the waiting time between current pulses is greater than or equal to a second waiting time threshold (eg, fifteen seconds). If the wait time is greater than or equal to the second wait time threshold at step 770, the controller 100 changes the indicator 110 at step 775, eg, activates the second LED 120 so that the second LED 120 appears to be always on. The module 225 then proceeds to the maintenance module 230 at step 780 .

If the waiting time is not greater than or equal to the second waiting time threshold at step 770 , the controller 100 determines whether the battery temperature is included in the range of -20°C to 0°C at step 785 . If the battery temperature is included in the range at step 785 , the module 225 proceeds to the step charging module 220 at step 790 . If the battery temperature is not included in the range at step 785 , the module 225 returns to the charging current algorithm 250 at step 740 .

FIG. 11 is a flowchart showing the maintenance module 230 . Operation of the module 230 begins at step 800 when the main charging operation 200 enters the maintenance module 230 . The controller 100 determines whether the battery voltage is included in the range of 3.5-V/cell to 4.05-V/cell at step 805 . If the battery voltage is not included in the range at step 805, the controller 100 continues to stay in step 805 until the battery voltage is included in the range. Once the battery voltage is included in the range at step 805 , the controller 100 initializes a maintenance timer at step 810 . In some configurations, the maintenance timer counts down from thirty minutes.

At step 815, the controller 100 determines whether the battery temperature is below -20°C or above 65°C. If the battery temperature is below -20° C. or above 65° C. at step 815 , the module 230 proceeds to the temperature out of range module 210 at step 820 and the module will end at step 825 . If the battery temperature is not below -20° C. or above 65° C. at step 815 , module 230 proceeds to charge current algorithm 250 at step 830 .

Once the charging current algorithm 250 is performed at step 830 , the controller 100 determines at step 835 whether the maintenance timer has expired. If the maintenance timer has expired, the module 230 proceeds to the faulty battery module 205 at step 840 and the module 230 will end at step 845 . If the maintenance timer has not expired at step 835, the controller 100 determines at step 850 whether the waiting time between current pulses is greater than or equal to a first prescribed maintenance waiting time period, eg, 15 seconds.

If the wait time at step 850 is greater than the first prescribed maintenance wait time period, the module 230 proceeds to step 805 . If the wait time is not greater than or equal to the first prescribed maintenance wait time period at step 850 , the module 230 proceeds to the charging current algorithm 250 at step 830 . In some constructions, the battery charger 30 will remain in the maintenance module 230 until the battery pack 20 is disconnected from the battery charger 30 .

FIG. 12 is a flowchart showing a basic charging schedule or charging current algorithm 250 . Operation of module 250 begins at step 870 when other modules 220 - 230 or main charging operation 200 enters charging current algorithm 250 . The controller 100 applies the full current pulse at step 875 for approximately 1 second. At step 880, while current is being applied to the battery 20, the controller 100 determines whether the battery voltage is greater than 4.6-V/cell.

If the battery voltage is greater than 4.6-V/cell at step 880 , the algorithm 250 proceeds to the faulty battery module 205 at step 885 and the algorithm 250 will end at step 890 . If the battery voltage is not greater than 4.6-V/cell at step 880, the controller 100 interrupts the charging current at step 895, increments a counter, such as a charging current counter, and stores the count value.

At step 900, the controller 100 determines whether the battery temperature is below -20°C or above 65°C. If the battery temperature is below -20° C. or exceeds 65° C. at step 900 , the algorithm 250 proceeds to the temperature out of range module 210 at step 905 and the algorithm 250 will terminate at step 910 . If the battery temperature is not lower than -20° C. or not higher than 65° C. at step 900 , the controller 100 measures the battery voltage when no charging current is applied to the battery 20 at step 915 .

At step 920, the controller 100 determines whether the battery voltage is less than 4.2-V/cell. If the battery voltage is less than 4.2-V/cell at step 920 , the algorithm 250 proceeds to step 875 . If the battery voltage is not less than 4.2-V/cell at step 920 , the controller 100 waits until the battery voltage is approximately equal to 4.2-V/cell at step 925 . Also at step 925, the controller 100 stores the waiting time. Algorithm 250 ends at step 930 .

In some constructions and in some aspects, battery charger 30 may include another method of operation for charging various batteries, such as batteries 20 having different chemistries and/or nominal voltages. An example of such a charging operation is shown in Figures 28-38. In some constructions and in some aspects, the battery charger 30 includes a battery for charging a Li-based battery, for example, having a Li-Co chemistry, a Li-Mn spinel chemistry, a Li-Mn nickel chemistry, etc. How to charge the battery. In some constructions and in some aspects, charging operation 200 includes various modules for performing different functions in response to different battery conditions and/or battery characteristics.

In some constructions and in some aspects, a charging method of operation includes means for interrupting charging based on abnormal and/or normal battery conditions. In some constructions, the charging operation includes a faulty battery module and/or a temperature out-of-range module, such as the temperature out-of-range module shown in flowchart 2235 of FIG. 36 . In some constructions, battery charger 30 accesses a faulty battery module to terminate charging based on abnormal battery voltage, abnormal cell voltage, and/or abnormal battery capacity. In some constructions, the battery charger 30 enters the temperature out of range module 2235 to terminate charging based on abnormal battery temperature and/or one or more abnormal battery cell temperatures. In some constructions, the charging operation includes more or fewer modules for terminating charging based on more or fewer battery conditions than those described above and described below.

In some constructions and in some aspects, the charging operation includes various modes or modules for charging the battery 20 according to various battery conditions or stages within the operation. In some constructions, the charging operation includes a trickle charging module, such as the trickle (limited) charging module shown in flowchart 2225 of FIG. type) module; a fast charging module, such as the fast charging module shown in the flowchart 2215 of FIG. 32; and/or a maintenance charging module, such as the maintenance module shown in the flowchart 2230 of FIG. 35; and other modules, For example, the flat battery pack wake-up module shown in the flowchart 2210 of Figure 31, and the charging module and battery pack insertion module 2200 (start Charge). Charging operations also include charging current algorithms implemented in various ways by other modules, such as the algorithm shown in flowchart 2240 of FIGS. 37 and 38 .

An example of a part of the charging operation will be given below with reference to FIGS. 28-30. For example, the charging operation starts from the battery pack insertion module 2200 as shown in FIG. 28 . The operation begins with powering the battery charger (at 2305 ), and the battery charger 30 determines whether the input voltage V _in is within the correct operating parameters (eg, 80V < V _in < 140V) (at 2310 ). If the input voltage _Vin is not within these operating parameters, the battery charger 30 inhibits charging (at 2315). Battery charger 30 may also indicate to the user whether the correct input voltage _Vin is being provided (at 2315).

If the battery charger 30 is receiving the correct input voltage _Vin , the battery pack 20 is connected to the charger (at 2325), and the charger 30 determines whether the correct connection (eg, between terminals) has been made ( at step 2330). If the correct connection has not been achieved, charger 30 does not illuminate any LEDs (at 2335), and the charging operation is terminated (at 2340). If a connection is made, the charger 30 detects the presence of the battery 20 by the voltage applied to the controller 100 (at 2345 ), and the controller 100 measures the voltage V _pack of the battery 20 (at 2350 ).

Charger 30 determines whether battery voltage V _pack is less than 5V (at 2355 ). If the battery voltage V _pack is less than 5V, the charging operation proceeds to the flat pack wake-up module 2210 (at 2360 ). If the battery voltage V _pack is not less than 5V, charger 30 attempts to establish communication with battery 20 (at 2365 ) and determines whether communication is established (at 2370 ). If communication is not established, charger 30 does not illuminate any indicators (at 2375), and the charging operation terminates (at 2380). If communication is established, charging operations continue with the charging module 2205 (at 2385).

The charging module 2205 is shown in FIGS. 29 and 30 . The charging module 2205 first lets the charger 30 identify the battery pack nominal voltage and sets appropriate measurement parameters (at 2405), and interrogates the cell voltages of the battery 20 (at 2410) to determine if any cell voltage is greater than the above Threshold (eg, 4.35V) (at 2415). If any cell is greater than the upper threshold, charger 30 does not activate any LEDs (at 2420 ), and the charging operation terminates (at 2425 ). If none of the cells are greater than the upper threshold, charger 30 measures the battery voltage at the terminals of charger 30 (at 2430) and interrogates the battery voltage V _pack measured by battery 20 (at 2435) to It is determined whether the measurements are consistent (at 2440). If the measurements do not agree, charger 30 does not activate any LEDs (at 2445), and the charging operation terminates (at 2450).

If the measurements agree, charger 30 interrogates the battery temperature of battery 20 (at 2455) to determine if the battery temperature is within the operating range (at 2460). If the battery voltage is not within the desired operating range, then operation proceeds to the temperature out of range module 2235 (at 2465), and once the charging operation leaves the temperature out of range module 2235, the charger 30 may again interrogate the battery 20 for battery temperature information (at 2455).

If the battery temperature is within the desired operating range, charger 30 determines whether the battery voltage V _pack is greater than a maintenance threshold (e.g., 4.1 V/cell) (at 2470 ), and if the battery voltage V _pack is greater than the maintenance threshold (at 2475 ), the charging operation proceeds to the maintenance module 2230. Otherwise, charger 30 determines whether battery voltage V _pack is less than a trickle threshold (e.g., 3.5 V/cell) (at 2480), and if battery voltage V _pack is below the trickle threshold, the charging operation proceeds to trickle (limited ) module 2225 (at 2485). If the battery voltage is not below the trickle threshold, charger 30 determines whether the battery temperature is within the trickle range (at 2490 ). If the temperature is within the trickle range, the operation proceeds to the trickle (step) module 2220 (at 2495), and if the temperature is not within the trickle range, proceeds to the fast charge module 2215 (at 2505) . Charging operations can continue as shown in the other blocks shown in Figures 31-38.

During the charging operation shown in FIGS. 28-38, battery charger 30 powers battery 20 using a pulse charging method. In one construction, the battery charger 30 provides the battery 20 with pulses each time having the same pulse width, but varying the time between the pulses. This is called "full charge current" or "full charge pulse". In other configurations such as those shown in FIGS. 16 and 39 , the overall charging current or overall charging pulses applied by the battery charger 30 may be scaled according to the individual cell voltages in the battery 20 . This application will be described below with reference to FIGS. 4 , 16 and 39 .

As shown in FIG. 4 , the controller 100 in the battery charger 30 is capable of receiving and transmitting information with respect to the microcontroller 64 in the battery 20 . In some constructions, microcontroller 64 may monitor various battery characteristics during charging, including the voltage or current state of each battery cell 60 , either automatically or in response to instructions from battery charger 30 . Microcontroller 64 is capable of monitoring certain battery characteristics and processes or average measurements during the charge current period T _on (ie, the "current on" time period). In some constructions, the current on time period may be approximately 1 second ("1-s"). During periods of no charging current ("current off" time periods) T _off , information about certain battery characteristics, such as cell voltage or cell state of charge, may be communicated from the battery 20 to the charger 30 . In some constructions, the current _off period Toff is approximately 50ms. The battery charger 30 may process the information sent from the battery 20 and vary the current on-time period T _on accordingly. For example, if one or more battery cells 60 have a higher current state of charge than other battery cells 60, battery charger 30 may reduce subsequent current on-time periods T _on in order to avoid charging one or more higher current states of charge. The battery unit is overcharged.

In some constructions, battery charger 30 may compare each individual cell voltage to an average cell voltage, and the difference between the individual cell voltages and the average cell voltage equals or exceeds a specified threshold (e.g., an imbalance threshold). In this case, charger 30 may identify the cell as a higher state of charge cell. The battery charger 30 can vary the current on-time period T _on . In other constructions, battery charger 30 may estimate the state of charge of a particular battery cell (eg, a cell identified as a higher voltage cell) during the current-on time period based on information received from battery 20 . In these configurations, battery charger 30 may vary the duration of current on-time period T _on if the estimate of the cell's current state of charge exceeds a threshold.

For example, as shown in FIGS. 16 and 39 , battery charger 30 may command battery 20 to average cell voltage measurements taken during the next current-on time period T _on1 . The command may be sent during the first current-off time period T _off1 . Thus, during the first current on time period T _on1 , microcontroller 64 measures and averages the cell voltages as well as other battery parameters. During the next current off time period T _off2 , the battery 30 may transmit the averaged measurement to the battery charger 30 . In some constructions, the battery 20 may transmit eight average measurements, such as an average battery pack state-of-charge measurement and an average individual cell state-of-charge for each of the seven battery cells 60 . For example, battery 20 may send the following information: unit 1 14%, unit 2 14%, unit 3 15%, unit 4 14%, unit 5 16%, unit 6 14%, unit 7 14%, and battery packs (e.g., Units 1-7) Voltage 29.96V. In this embodiment, battery charger 30 identifies cell 5 as a higher battery cell. The charger 30 also records the battery voltage measured by the battery microcontroller 64 and the battery charger 30 . In this example, the battery charger 30 measures a battery voltage of approximately 30.07V. The battery charger 30 calculates the difference in battery voltage measurements (eg, 110 mV) and determines that the voltage drop across the terminals and leads is approximately 110 mV.

During the subsequent current on time period T _on2 the battery charger 30 estimates the voltage of the cell 5 . For example, the battery charger 30 samples voltage measurements of the battery 20 and, for each battery voltage measurement, estimates the state of charge of the cell 5 according to the following formula:

(V _battery/ch -V _terminal ) *V _unit

where Vbattery _/ch is the voltage of the battery 20 as measured by the charger 30, _Vterminal is the voltage drop across these terminals (eg, 110 mV), and _Vunit is the cell voltage estimated as a percentage of the battery voltage. If the voltage estimate of cell 5 exceeds a threshold ("lower threshold"), battery charger 30 may vary the subsequent current on-time period T _on3 . In this embodiment, the battery charger 30 remembers when the estimated (or calculated) voltage of the cell 5 reaches a lowering threshold of approximately 800 ms. As shown in FIG. 39 , charger 30 identifies and counts cell 5 as a high cell, and changes the subsequent current on time period T _on3 to be approximately equal to the duration charger 30 remembers (eg, 800 ms). Therefore, the length T ₂ of the current on-time period T _on3 is smaller than the length T ₁ of the previous current on-time periods T _on1 and T _on2 .

In some constructions, the charger 30 continues to set subsequent current-on time periods (eg, T _on4-5 ) to approximately the length T ₂ of the preceding current-on-time period T _on3 (eg, 800 ms). If cell 5 (or another cell) continues to be identified as a high cell, for example, if cell 5's voltage continues to reach a lowering threshold (eg, at 600 ms), charger 30 may switch current on for subsequent periods of time The length of (eg, T _on6 ) is changed from a length of T ₂ (eg, about 800 ms) to T ₃ (eg, about 600 ms).

In other constructions, in the event charger 30 determines that a cell is not receiving sufficient current, charger 30 may also set the subsequent current-on time period (e.g., T _on5 ) back to a length of about T ₁ (thus Increased on-time after decreasing on-time). For example, if battery charger 30 determines that the voltage of cell 5, despite being a high or unbalanced cell, is well below the lowering threshold at the end of the on-time period, battery charger 30 may increase the current on-time period. In these configurations, the battery charger 30 may continue to vary the length of the current pulses (eg, on-time periods) based on the battery cell voltages to optimize the amount of charge the cells receive in the event of a slight overcharge. In some constructions, the battery charger 30 is unable to increase the current on-time beyond an initial current-on-time period, such as period T _on1 .

Another schematic view of the battery 20' is shown schematically in Fig. 13 . Battery 20' is similar to battery 20, and common elements are indicated by the same reference numeral "'".

In some constructions, the circuit 62' includes electronic components, such as an identification resistor 950, and the identification resistor 950 may have a set resistance. In other configurations, an electronic component may be a capacitor, inductor, resistor, semiconductor element, circuit, or other component that has resistance or is capable of sending electrical signals, such as a microprocessor, digital logic component, or the like. In the illustrated construction, the resistance value of the identification resistor 950 may be selected based on the characteristics of the battery 30', such as the nominal voltage and chemical composition of the battery cells 60'. The detection terminal 55' may be electrically connected to the identification resistor 950.

The battery 20&apos; shown schematically in Figure 13 may be electrically connected to an electrical device, such as a battery charger 960 (also shown schematically). Battery charger 960 may include a positive terminal 964 , a negative terminal 968 and a sense terminal 972 . Each terminal 964, 968, 972 of the battery charger 960 may be electrically connected to a corresponding terminal 45', 50', 55' (respectively) of the battery 20'. The battery charger 960 may also include circuitry having electrical components such as a first resistor 976, a second resistor 980, solid state electronics or semiconductors 984, a comparator 988, and a processor, microcontroller or controller (not shown). In some constructions, semiconductor 984 may include a transistor capable of operating in a saturated or "ON" state and capable of operating in an off or "OFF" state. In some constructions, comparator 988 may be a dedicated voltage monitoring device, microprocessor or processing unit. In other constructions, the comparator 988 may be included in the controller (not shown).

In some constructions, a controller (not shown) may be programmed to recognize electrical components in the battery 20&apos;, such as to recognize the resistance value of the resistor 950. The controller can also be programmed to determine one or more characteristics of the battery 20', such as the battery chemistry and nominal voltage of the battery 20'. As noted previously, the resistance value of identification resistor 950 may correspond to a specific value associated with one or more specific battery characteristics. For example, the resistance value of the identification resistor 950 may be included in a range of resistance values corresponding to the chemical composition and nominal voltage of the battery 20'.

In some constructions, the controller may be programmed to recognize multiple resistance ranges for the identification resistor 950 . In these structures, each range corresponds to a battery chemistry such as NiCd, NiMH, Li-ion, etc. In some constructions, the controller may identify additional resistance ranges, each corresponding to another battery chemistry or another battery characteristic.

In some constructions, the controller can be programmed to recognize multiple voltage ranges. The voltage included in the voltage range may depend on or correspond to the resistance value of the identification resistor 950 so that the controller can determine the value of the resistor 950 from the measured voltage.

In some constructions, the resistance value of identification resistor 950 may further be selected to be unique for each possible nominal voltage value of battery 20&apos;. For example, in one range of resistance values, a first specific resistance value may correspond to a nominal voltage of 21V, a second specific resistance value may correspond to a nominal voltage of 16.8V, and a third specific resistance value may correspond to a nominal voltage of 12.6V. called voltage correspondence. In some configurations, there may be more or fewer specific resistance values, each corresponding to another possible nominal voltage of the battery 20&apos; associated with the resistance range.

In the exemplary embodiment, battery 20 ′ is electrically connected to battery charger 960 . To identify the first battery characteristic, semiconductor 984 is switched to an "ON" state under the control of additional circuitry (not shown). Identification resistor 950 and resistors 976 and 980 form a voltage divider network when semiconductor 984 is in the "ON" state. The network establishes a voltage V _A at a first reference point 992 . If the resistance of resistor 980 is significantly lower than the resistance of resistor 976 , voltage V _A will depend on the resistance of identification resistor 950 and resistor 980 . In this embodiment, voltage V _A is in a range determined by the resistance value of identification resistor 950 . A controller (not shown) measures the voltage V _A at the first reference point 992 and determines the resistance value of the identification resistor 950 based on the voltage V _A . In some constructions, the controller compares voltage V _A to multiple voltage ranges to determine battery characteristics.

In some constructions, the first battery characteristic to be identified may include battery chemistry. For example, any resistance value below 150 kΩ may indicate that the battery 20' has a NiCd or NiMH chemistry, and any resistance value of about 150 kΩ or higher may indicate that the battery 20' has a Li or Li ion chemistry. Once the controller has determined and identified the chemistry of the battery 20', an appropriate charging algorithm or method can be selected. In other configurations, there are more resistance ranges than in the above embodiment, each range corresponding to another battery chemistry.

Continuing with the exemplary embodiment, to identify the second battery characteristic, semiconductor 984 is switched to an "OFF" state under the control of additional circuitry. Identification resistor 950 and resistor 976 form a voltage divider network when semiconductor 984 is switched to the "OFF" state. The voltage V _A at the first reference point 992 is now determined by the resistance values of the identification resistor 950 and the resistor 976 . The resistance value of the identification resistor 950 is selected such that when the voltage V _BATT at the second reference point 1012 is substantially equal to the nominal voltage of the battery 20', the voltage V _A at the first reference point 992 is substantially equal to the second Voltage V _REF at three reference points 996 . If V _A at the first reference point 992 exceeds the voltage V _REF at the third reference point 996 , the output V _OUT of the comparator 988 changes state. In some constructions, the output V _OUT may be used to terminate charging or as an indicator to initiate additional functions such as maintenance procedures, equalization procedures, discharge functions, additional charging schemes, and the like. In some constructions, voltage V _REF may be a fixed reference voltage.

In some constructions, the second battery characteristic to be identified may include the nominal voltage of the battery 20&apos;. For example, a general formula for calculating the resistance value of identification resistor 958 may be:

${\mathrm{<span\; class="notranslate">\; <figure-callout\; id="100"\; label="R"\; filenames="H05824998820070126E000041.png"\; state="\{\{state\}\}">R</figure-callout></span>}}_{\mathrm{<span\; class="notranslate">\; 100</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; REF</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; 135</span>}}}{{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; BATT</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; V</span>}}_{\mathrm{<span\; class="notranslate">\; REF</span>}}}$

Where R ₁₀₀ is the resistance of identification resistor 950 , R ₁₃₅ is the resistance of resistor 976 , V _BATT is the nominal voltage of battery 20 ′, and V _REF is a fixed voltage, such as approximately 2.5V. For example, in the range of resistance values for the Li ion chemical composition (set forth above), a resistance value of about 150 kΩ for identification resistor 950 may correspond to a nominal voltage of about 21 V, and a resistance value of about 194 kΩ may correspond to about A nominal voltage of 16.8V, and a resistance value of approximately 274.7kΩ may correspond to a nominal voltage of approximately 12.6V. In other constructions, more or fewer specific resistance values may correspond to additional or different battery pack nominal voltage values.

In the illustrated configuration, both the identification resistance value 950 and the third reference point 996 may be located on the “high” side of the current sense resistor 1000 . Setting identification resistor 950 and third reference point 996 in such a way reduces any relative voltage fluctuations between _VA and V _REF when charging current is present. If the identification resistor 950 and the third reference point 996 are referred to as the ground point 1004 and a charging current is applied to the battery 20', a voltage fluctuation occurs in the voltage _VA .

In some constructions, battery charger 960 may also include charger control functionality. As before, when voltage _VA is substantially equal to voltage V _REF (indicating that V _BATT is equal to the nominal voltage of battery 20'), the output V _OUT of comparator 988 changes state. In some constructions, when the output V _OUT of the comparator 988 changes state, charging current is no longer provided to the battery 20 ′. Once the charging current is interrupted, the battery voltage V _BATT starts to decrease. When voltage V _BATT reaches the lower threshold, the output V _OUT of comparator 988 changes state again. In some constructions, the lower threshold of voltage V _BATT is determined by the resistance value of hysteresis resistor 1008 . Once the output V _OUT of comparator 988 changes state again, the charging current is re-established. In some constructions, the loop repeats for a specified amount of time as determined by the controller, or for a specified amount of state change implemented by comparator 988 . In some constructions, this cycle repeats until the battery 20 ′ is disconnected from the battery charger 960 .

In some constructions and in some aspects, a battery, such as battery 20 shown in FIG. 17 , may become so discharged that battery cells 60 may not have sufficient voltage to communicate with battery charger 30 . As shown in FIG. 17, the battery 20 may include one or more battery cells 60, a positive terminal 1105, a negative terminal 1110, and one or more test terminals 1120a and 1120b (as shown in FIG. 17, a second test terminal or start terminal 1120b may or may not be included in battery 20). Battery 20 may also include circuitry 1130 with microcontroller 1140 .

As shown in FIG. 17, circuit 1130 may include a semiconductor switch 1180 that interrupts when circuit 1130 (e.g., microprocessor 1140) determines or detects a condition above or below a predetermined threshold (e.g., an "abnormal battery condition") Discharge current. In some constructions, the switch 1180 includes an interrupt condition, in which current flow from or to the battery 20 is interrupted, and an enable condition, in which current flow to or from the battery 20 is permitted. In some constructions, abnormal battery conditions may include, for example, high or low cell temperature, high or low battery state of charge, high or low cell state of charge, high or low discharge current, high or low charge current, and the like. In the illustrated configuration, switch 1180 comprises a power FET or a metal oxide semiconductor FET ("MOSFET"). In other configurations, the circuit 1130 may include two switches 1180 . In these configurations, switches 1180 may be arranged in parallel. Parallel switch 1180 may be included in battery packs (eg, batteries 20 powering circular saws, drills, etc.) that provide a high average discharge current.

In some constructions, once the switch 1180 becomes non-conductive, the switch 1180 will not reset even if the abnormal condition is no longer detected. In some constructions, circuitry 1130 (eg, microprocessor 1140 ) may reset switch 180 only if an electrical device, such as battery charger 30 , instructs microprocessor 1140 to do so. As before, the battery 20 may become so discharged that the battery cells 60 may not have sufficient voltage to power the microprocessor 1140 to communicate with the battery charger 30 .

In some configurations, if the battery 20 cannot communicate with the charger 30 , the battery charger 30 can provide a small charging current through the body diode 1210 of the switch 1180 to slowly charge the battery cell 60 . Once the cells 60 receive sufficient charging current to power the microprocessor 1140 , the microprocessor 1140 may change the state of the switch 1180 . That is, the battery 20 can be charged even when the switch 1180 is in a non-conductive state. As shown in FIG. 17, switch 1180 may include a body diode 1210, which in some configurations is integral with MOSFETs and other transistors. In other configurations, diode 1210 may be electrically connected in parallel with switch 1180 .

In some constructions, if the battery 20 cannot communicate with the charger 30, the battery charger 30 can apply a small average current through a sense lead, such as the sense lead 1120a or the dedicated enable terminal 1120b. The current can charge capacitor 1150, which in turn can provide sufficient voltage to microprocessor 1140 to be able to operate.

The structures described above and shown in these drawings are given by way of example only, and do not limit the concept and principle of the present invention. Accordingly, those of ordinary skill in the art will understand that various changes may be made in these elements, as well as their construction and arrangement, without departing from the spirit and scope of the invention.

Claims (20)

1. An assembly for pulse charging a battery having a plurality of cells comprising: A battery pack comprising: a first battery terminal; a second battery terminal; a plurality of battery cells each having a lithium-based chemistry and a current state of charge, the battery cells connected to at least one of the first battery terminal and the second battery terminal ;as well as a battery microcontroller coupled to at least one of said first battery terminal and said second battery terminal for measuring the current state of charge of at least one of said battery cells to generate a battery cell current state of charge state-of-charge measurements; and A battery charger, the battery charger is used to provide charging current to the battery pack, the battery charger includes: A first charger terminal configured to be connected to at least one of the first battery terminal and the second battery terminal, the first charger terminal configured to provide the battery pack with recharging current; a second charger terminal configured to connect to at least one of the first battery terminal and the second battery terminal; and a charger microcontroller connected to the second charger terminal and adapted to receive measurements of the current state of charge of the battery cells from the battery microcontroller, the charger microcontroller It is also used to provide charging current to the battery pack in the form of pulses, wherein each pulse includes a first time interval and a second time interval, during the first time interval, the charging current is being provided to the battery, and during the second time interval During the time interval during which the supply of charging current to the battery is suspended, the charger microcontroller is further configured to vary the first of the pulses based at least in part on a measurement of the current state of charge of the battery cells received from the battery microcontroller. time interval. 2. The assembly of claim 1, wherein the chemical composition is a Li ion based chemical composition. the 3. The assembly of claim 1 , wherein the charger microcontroller is further configured to vary the second time of the pulse based at least in part on a measurement of the current state of charge of the battery cell received from the battery microcontroller. interval. 4. The assembly of claim 1 , wherein said battery pack has a battery pack state of charge that is the sum of each current state of charge of said plurality of battery cells, said battery microcontroller Also used to measure battery pack state of charge to generate battery pack state of charge measurements. 5. The assembly of claim 4, wherein the charger microcontroller is operative to measure the battery state of charge to generate a second battery state of charge measurement. 6. The assembly of claim 5, wherein the second battery pack SOC measurement measured by the charger microcontroller is greater than the battery pack SOC measurement measured by the battery microcontroller. 7. The assembly of claim 5, wherein the battery microcontroller estimates the current state of charge of each of the plurality of battery cells as a percentage of the battery pack state of charge measured by the battery microcontroller, and sending the estimated percentages for each of the plurality of battery cells. 8. The assembly of claim 7, wherein said charger microcontroller is adapted to estimate the current state of charge of the battery cell during the first time interval to produce an estimated state of charge measurement of the battery cell, the charger microcontroller is also configured to vary the subsequent pulses based on the estimated state of charge measurement of the battery cell first time interval. 9. The assembly of claim 1, wherein the battery charger is further configured to vary the second time interval of the pulses. the 10. A battery charger for providing charging current to a lithium-based battery pack having a plurality of battery cells and a battery microcontroller, each of said battery cells having a lithium-based chemistry and a current state of charge, the battery microcontroller is used to measure the current state of charge of the battery cells of at least one of the battery cells, the battery charger includes: The charger microcontroller is used to receive the current charging state of the battery unit from the battery microcontroller, and the charger microcontroller is also used to provide charging current to the lithium-based battery pack in the form of pulses, wherein each A pulse includes a first time interval and a second time interval, the first time interval is an interval for supplying charging current to the battery pack, and the second time interval is an interval for suspending supply of charging current to the battery pack The charger microcontroller is further configured to vary the first time interval of the pulses based at least in part on the current state of charge of the battery cells received from the battery microcontroller. 11. The battery charger as claimed in claim 10, wherein said battery microcontroller is adapted to measure the current state of charge of each of said plurality of battery cells, and said charger microcontroller is adapted to receive each battery cell charge state. 12. The battery charger of claim 11, wherein said battery pack has a pack voltage that is the sum of each current state of charge of said plurality of battery cells, said charger microcontroller tor is also used to receive battery pack charge status. 13. The battery charger of claim 10, wherein the battery charger is further configured to vary the second time interval of the pulses. 14. A method of pulse charging a battery having a plurality of cells, the method comprising: measuring a state of charge of each battery cell in the plurality of battery cells, each of the battery cells having a lithium-based chemistry; applying a first pulse of charging current to the battery, the first pulse having a first time interval during which charging current is supplied to the battery and a second time interval during which charging current to the battery is suspended. the battery provides charging current; and applying a second pulse of charging current to the battery, the second pulse having a third time interval and a fourth time interval, during the third time interval, the charging current is supplied to the battery, during the fourth time interval, Providing charging current to the battery is suspended, the third time interval is based at least in part on a state of charge of the battery cells, and the third time interval is less than the first time interval. 15. The pulse charging method of claim 14, further comprising: A battery cell of the plurality of battery cells having a higher state of charge than other battery cells of the plurality of battery cells is identified. 16. The pulse charging method of claim 15, further comprising: measure the battery state of charge; and A state of charge of the identified battery cell is estimated to generate an estimated state of charge of the battery cell. 17. The pulse charging method of claim 16, wherein the third time interval is based at least in part on an estimated state of charge of the battery cell. 18. The pulse charging method of claim 16, further comprising: establishing a battery cell state-of-charge threshold; and An estimated time is calculated when the estimated state of charge of the battery cell reaches a battery cell state of charge threshold. 19. The pulse charging method of claim 18, wherein said third time interval is approximately equal to said estimated time. 20. The pulse charging method of claim 14, further comprising: maintaining the parameter value representing said third time interval; and The value of the parameter is varied based at least in part on the state of charge of the battery cell. the

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