DE19535294A1 - Monitoring system for monitoring battery powered vehicle, such as fork-lift truck, and its battery - Google Patents

Abstract

The monitoring system has a measuring/evaluation unit (2) for determining the condition data of the battery (1), also generating of the warning and/or the control commands for the application of the battery and of the vehicle according to the condition data. The measuring/evaluation unit and an indicating unit (3), for indicating the condition data and the control and warning commands, together with the battery are accommodated on the vehicle. A warning or a control command can be generated, which concerns the service due of the battery and/or blocks the operation of the vehicle entirely or partly. With the measuring/evaluation unit one or more of the following condition data is determinable. The voltage (U) or the voltage (Ut) of the individual battery cells. The ratio (U/Ut). The charge and discharge times over a period. The rated capacity of the battery and the residual capacity.

Description

The invention relates to a device for monitoring a battery-operated Vehicle and its battery according to the preamble of claim 1 you also relates to methods of monitoring a battery powered vehicle and its battery.

Battery-powered vehicles are used on a large scale in transport technology used. Examples of this are forklifts or automatically controlled ones Vehicles in factory halls for the transportation of goods or the battery powered City car with which emission-free individual transport is possible. Alone in the Germany is a total of well over 100,000 industrial trucks in use.

Batteries are used to drive such vehicles (also as traction batteries designated), which are first loaded and then used on the vehicle. They are slowly exhausted by the current draw during operation and have to be reloaded. This takes place on a so-called "Charging station", where the batteries are connected to a charger and either stay on the vehicle or be separated from it. Batteries of this type only know one of the two states "charge" or  "Discharge" and are therefore hereinafter referred to as "intermittent" Batteries ". This term is intended to differentiate batteries from those a charger is connected during normal operation, e.g. B. at a battery used in a motor vehicle is the case.

In general, these batteries are lead accumulators However, other electrochemical systems are also used, such as. B. Nickel / cadmium batteries. In the batteries that operate in the federal Republic of Germany existing vehicles can be used in total an amount of energy of approx. GWh of electrical energy can be stored per Approx. 3-4 GWh of energy are required to charge each working day.

The technical development of rechargeable batteries (also triggered through the effort to use energy sparingly) has the knowledge brought that their lifespan can be increased considerably if the Certain precautions are followed during loading / unloading operations. So is z. B. known that a lead acid battery should not experience a deep discharge because the electrochemical system due to sludge formation in the battery is affected. Systems were therefore used to prevent deep discharge developed the voltage curve of the battery during discharge analyze and so infer their charge state or the during the Measure the drawn current over time and from the current / time Integrally determine the amount of charge removed and thus the charge status close the battery. Some of these systems generate one when the value falls below Limit value a signal with which the main consumers are switched off (at a forklift z. B. the lifting motors; Lift cutout).

It was also recognized that charging the battery was made gentler can take into account the electrochemical characteristics of the battery will be carried. This led to the development of chargers designed for one work predetermined program, which ensures that the charging current Function of the state of charge already reached. Such chargers rework special characteristics, e.g. B. are known as IUIa or IOIUIa characteristic (see see VDE 0510 / DIN 57 510).

The known surveillance systems have a number of disadvantages and in particular do not guarantee comprehensive protection of the battery unfavorable operating conditions. So there are z. B. not really safe yet  Protection against overcharging because even chargers that are fully charged Recognize the battery by the voltage level, one for safely fully charging the battery Provide a minimum charging time that can damage the battery. Furthermore there is no surveillance system with which also in relation to the vehicle - not only regarding the battery - unfavorable operating conditions should be avoided can.

The invention has as its object means for comprehensive monitoring of a to provide battery-powered vehicle and its battery with a gentle one by avoiding unfavorable operating conditions Operation of vehicle and battery is possible.

This object is achieved with a device according to claim 1 and with Method according to claims 16 and 18.

The invention is based on the knowledge that a comprehensive avoidance of unfavorable operating conditions is only possible if the status data of the Battery not only determined and stored, but also consistently for through command structure with which on-site (i.e. on the battery-powered vehicle) and immediately (i.e., at the time of this Condition occurs) Measures are taken to prevent such operating conditions from occurring don't let it happen. For this purpose, according to the invention at a front Direction for monitoring a battery-operated vehicle and its battery a measuring / evaluation unit for determining the status data of the battery, and for Generation of warning and / or control commands for the use of the battery and of the vehicle in accordance with the status data, a display unit for Representation of the status data and the control and warning commands together with the Battery housed on the vehicle.

This arrangement has the advantage that the control commands for the use of the battery and the vehicle can be generated on site and immediately to avoid unfavorable operating conditions can be used. Because both the determination of the Status data of the battery as well as the command structure derived from it protection against unfavorable operation is extensive conditions comprehensive. The invention thus avoids disadvantages of known ones Devices that could only ever solve subtasks. In particular, the Overcomes disadvantages of systems that work with a central computer that is not on the vehicle. Such a computer can only be used in the  Intervene in the charging process, but not in the operation of the battery and above beyond - in the operation of the vehicle itself.

According to a preferred embodiment of the invention, the measurement / off a warning or control command can be generated on the value unit, indicating that maintenance is due the battery and / or the vehicle and / or the charging process Battery locks and / or blocks the operation of the vehicle in whole or in part.

Available ones can be used to determine the status data of the battery Devices are used, which are known under the name "battery controller". These are measuring devices with which one or more of the the following status data can be determined:

I: current drawn from the battery and / or fed into the battery;
U, U _t : voltage of the battery (U) and / or individual battery cells (U _t );
U / U _t : ratio value;
t: time;
T: temperature of the battery and / or individual battery cells;
Q _e : amount of charge fed into the battery during a preselected period of time;
Q _a : amount of charge removed from the battery during a preselected period of time;
Q: difference (Q _e - Q _a );
Δ / Q _n : ratio, where Q _{n is} the nominal capacity of the battery;
Q _t : remaining capacity of the battery.

The basic data measured on the battery are the current 1 , which is generally measured in the shunt and is available in the form of a current-proportional voltage value. In addition, the total voltage U and optionally the voltage U _{t of} individual battery cells are determined. With the aid of temperature sensors provided on the battery, it is also possible to determine the temperature T of the battery or individual battery cells.

Derived data can be determined from the aforementioned basic data (I, U, U _t , T), the ratio value U / U _{t being} of interest first. This ratio indicates whether individual battery cells are weakened compared to the other cells. If the number of cells in the battery is n and the partial voltage U _{t is} tapped over n / 2 cells, the following condition must be fulfilled for cells with the same power when discharging:

U / U _t = n / (n / 2) = 2

If there is a weakened cell under the cells via which U _{t is} tapped, the value of U- is less than theoretical, and it is U / U _t <2. This means that the size of this ratio can be used to weaken individual cells getting closed. Even when loading, there is a change in the theoretical value for weakened, defective or unequal cells.

If the measurement of 1 is time-dependent, the current / time Integrally formed and thus the one fed into or taken from the battery Amount of charge that is usually measured in ampere hours (Ah) is specified. Microchips are available to form the current / time integral Available.

With the help of the current / time integral (with simultaneous recording of the absolute time), it is possible to determine further derived status data in the form of the amount of charge Q _e fed into the battery or the amount of charge Q _a taken from the battery during a preselected period of time. In addition, the difference .DELTA.Q = (Q _e - Q _a ) can be determined, which (as will be explained) prevents overcharging. The ratio ΔQ / Q _n can be determined as a further derived variable, where Q _n denotes the nominal capacity of the battery.

According to a preferred embodiment of the invention, the measurement / off Control unit or warning commands can be generated if at least one of the above-mentioned state data over or above a predetermined limit value falls below. A single limit can be chosen by others State data dependent.

With the device according to the invention, use-dependent maintenance of the Battery possible with the first damage to the battery due to excessive Overcharge is safely prevented. Overloading is known to be a Battery compromised in two ways. For one, find unwanted ones electrochemical processes instead if, for example, with a lead accumulator all Pb (II) on one electrode is oxidized to Pb (IV) and on the other electrode  Pb (0) has been reduced. In recent electrochemical research, the constant overcharging of a fully charged battery is even referred to as a way of leads to loss of capacity in a defined manner. Second, after one Charge over and above the nominal capacity, the supplied energy for the most part in Converted heat or electrolysis to water, producing hydrogen (Gases of the cell). In this way, overloading occurs with frequent Water loss, which is occasionally compensated for by the addition of distilled water must be chen. In the following, the term "maintenance of a battery" understood a measure in which in any case (i.e. optionally together with other measures) water is refilled. The latter effect overloading, d. H. the water loss caused thereby has the greater economic importance because the maintenance required for this is high and if maintenance is not carried out, the battery will be destroyed very quickly.

It is known that the larger the battery, the higher the overcharge their nominal capacity is. For conventional batteries with liquid electrolytes and A charger with an IUIa characteristic is a guide that water should be refilled should be when the overload is 50% of the nominal capacity. For batteries with IOIUIa characteristic and electrolyte circulation, on the other hand, the difference up to amount to ten times the nominal capacity.

The device according to the invention enables maintenance-dependent maintenance of the battery by first bringing the battery into a defined initial state, ie charging and maintaining it (refilling water). Then the charge quantity Q _e and the charge quantity Q _a fed in during this time are determined via the subsequent charging / discharging processes (hereinafter referred to as "cycles") and the difference ΔQ = (Q _e -Q _a ) is determined therefrom. There is no overcharge if Q _e = Q _a , ie ΔQ = 0. If ΔQ assumes finite values, the size of the overcharge can be determined and related to the nominal capacity of the battery Q _n , ie the ratio value ΔQ / Q _{n is} formed . This ratio is a measure of the time at which the battery should be serviced with water refilled. In the present example, ie with conventional batteries with liquid electrolyte and a charger with IUIa characteristic and a permissible difference of 50% of the nominal capacity, maintenance of the battery at ΔQ / Q _n = 0.5 is required.

According to a preferred embodiment of the invention, therefore, a warning command indicating that the battery is due for maintenance can be generated if ΔQ / Q _n , measured after the maintenance and charging of the battery has taken place during the subsequent charging / discharging processes (cycles) of the battery exceeds the predetermined limit G₁. In practice, this limit value G 1 is chosen so that it only triggers a warning (warning command) on the display unit, which still allows the battery to continue operating. If maintenance is then not carried out and a further increase in the ratio ΔQ / Q _{n is} permitted, a control command can be generated when a second limit value G₂ (G₂ <G₁) is exceeded, which prevents the battery from being charged until water is refilled (ie Maintenance is done) and the lock command is reset. In this way, a command structure is created, which intervenes on site when the use-dependent maintenance of a battery is required, and which makes it impossible to charge the battery beforehand due to the limit value G₂.

The invention is therefore also a method for monitoring an intermittently operated battery, in which after maintenance and charging of the battery during the subsequent charging / discharging processes by a measuring / evaluating unit, the sum Q _{a of} the amount of charge removed from the battery and the sum Q _{e of} the fed-in charge quantity is determined and from this the difference ΔQ = Q _e -Q _{a is} determined and related to the nominal capacity Q _{n of} the battery, and a warning command is generated by the measurement / evaluation unit, which indicates the need for maintenance of the Battery indicates when the ratio value ΔO / Q _n exceeds a preselected limit G₁.

According to a preferred embodiment of this method, a control command is generated by the measurement / evaluation unit, which blocks the charging of the battery when the ratio value ΔO / Q _n exceeds a limit value G₂, G₂ <G₁.

According to a further preferred embodiment of the present invention takes place (alternatively or together with the use described above dependent maintenance of the battery) a usage-dependent maintenance of the battery driven vehicle. In practice it has been found that the maintenance of the Vehicle should not take place after hours of operation, but after one certain energy throughput, e.g. B. a hundred times the nominal capacity. The Maintenance based on energy throughput is therefore a better one Criterion because operating states with higher energy throughput (where the vehicle is used more) are weighted higher than operating conditions in which the vehicle is in the average range of  Energy consumption, and vice versa. Only when used near the medium energy consumption is therefore a maintenance of the vehicle in accordance with of operating hours is the sensible criterion. This means that also at Vehicle-based maintenance brings advantages.

With the device according to the invention, use-dependent maintenance of the vehicle is possible by also bringing the vehicle into a defined initial state, ie servicing, here too. During the subsequent charging / discharging processes of the battery (again briefly referred to as "cycles"), the measuring evaluation unit determines the charging quantity Q _a taken from the battery and adds it up over all subsequent cycles. If Q _a exceeds a preselected limit value G₃, a warning command is generated analogously to the usage-dependent maintenance of the battery, which indicates that the vehicle is due for maintenance, and then, if a limit value G₄ (G₄ <G₃) is exceeded, a control command which the further Blocking operation of the vehicle in whole or in part.

The present invention therefore also relates to a method for monitoring a battery-operated vehicle, in which, after the vehicle has been serviced during the subsequent charging / discharging processes of the battery, the charge quantity Q _a removed from the battery is determined by a measuring / evaluating unit and measured / Evaluation unit a warning command is generated, which indicates the need for maintenance of the vehicle when Q _a exceeds a pre-selected limit value G₃. According to a preferred embodiment of this method, a control command is generated by the measurement / evaluation unit, which blocks the operation of the vehicle in whole or in part when Q _a exceeds a limit value G₄, where G₄ <G₃.

According to a further preferred embodiment of the device according to the invention, a control command can be generated which, when a limit value for the temperature T of the battery is exceeded, partially blocks the operation of the vehicle by switching off its main consumer and / or blocking the charging of the battery. In addition, a control command is possible which switches off the main consumers of the battery-operated vehicle when a limit value for U / U _{t is} exceeded and / or simultaneously blocks the charging of the battery.

Under the term "main consumer" those consumers become one understood battery-powered vehicle that consume the most energy and therefore most damaging if they reach a limit  continue to operate. The main consumers of a forklift are in the essentially the lifting motors. If the decommissioning is limited to this Ver need, then the drive motors can still be operated and the vehicle can still be driven for maintenance. This is under security considerations required because a vehicle that is no longer drivable in a factory premises possibly represents a security risk.

According to a further preferred embodiment of the invention, the Measuring / evaluation unit with the battery and the display unit with the Vehicle connected, the connection between the measuring / evaluation unit and Display unit via a cable with a detachable connector.

The functions of the measurement / evaluation unit can advantageously be used for Determination of the status data and / or to generate the warning and / or Control commands are taken over in whole or in part by a microprocessor. This has the advantage that the program of the microprocessor can be chosen freely can be changed, which means maximum flexibility in monitoring of vehicle and battery, taking into account numerous dependencies of the Limit values from the individual status data and when designing the Command structure is guaranteed.

Further advantages, features and possible uses of the invention result from the following description of preferred embodiments in Connection with the drawing; show it:

Fig. 1 is a schematic representation of a device according to the invention comprises a battery 1, a measuring / evaluation unit 2 and a display unit 3;

FIG. 2 shows the embodiment of FIG. 1 in the operating phase in which the charging of the battery 1 is being prepared;

Fig. 3 is a modification of the embodiment of Figure 1, wherein the measurement / evaluation unit 2 is housed on the battery 1.

Fig. 4 is a detailed representation of a signal pen.

Fig. 1 shows an inventive device with a battery 1, a measuring / evaluation unit 2 and a display unit 3. The battery 1 can be connected via a plug pair 11 , 12 to the consumers of a battery-operated vehicle, reference number 10 denoting the drive motor of the battery-operated vehicle and reference numeral 15 the main consumer (in the case of a fork-lift truck, the lifting motor).

From the measuring / evaluation unit 2 leads a line L₄ to a switch S. With the line L ein a control command is transmitted, which selectively switches off the main consumer 15 of the battery-powered vehicle without also switching off the drive motor 10 . With l is a symbol in the circuit Stromstromßge advises, from which a line l₂ emanates, which transmits the measured current value to the measuring / evaluation unit. Correspondingly, it is the case with a line l 3, which starts from a voltage measuring device U placed over the battery voltage. To the left of the voltage measuring device U, the voltage supply branches and leads directly to the drive motor 10 and via the switch S to the main consumer 15 . In a corresponding manner, a control command that blocks the charge of the battery can be transmitted via the line l 1 from the measurement / evaluation unit 2 to the battery-side connector 12 of the connector pair 11 , 12 . This is explained in more detail in FIG. 2.

1 Fig. 2 shows in addition to the components of FIG. A modified charger 14, a mating connector 13 with the battery connector 1 2 of the connector pair 11, 12 is connectable. The battery-side connector has a first connector socket 20 and a second connector socket 21 , which come into contact with the first connector pin 23 and the second connector pin 24 of the mating connector 13 when the connector pair 12 , 13 is plugged together. In addition, a signal connection in the form of a signal pin 22 is provided in the battery-side connector 12 , which is designed to match a corresponding signal socket 25 of the counter connector 13 . After plugging together the connector pair 12 , 13 , it is possible to transmit the control command provided by the line l 1 to block the charging process of the battery via the signal pin 22 or the signal socket 25 to a logic which is provided in the modified charger 14 . For this purpose, the line l₅, which is connected to the signal socket 25 of the mating connector 13 and to the charger 14 .

FIG. 3 shows a modified embodiment of the device from FIG. 1, in which the measurement / evaluation unit 2 is firmly connected to the battery 1 . In addition, the devices for voltage and current measurement U, I (and thus the lines l₂ and l₃) are integrated into the overall structure of the battery 1 . The tubular element, with which both the measurement / evaluation unit 2 and the display unit 3 is shown in FIG. 2, is shown in abbreviated form to indicate that it only comprises the display unit 3 .

The connection between the measuring / evaluation unit 2 housed on the battery 1 and the display unit 3 takes place via a detachable plug connection with which the lines l₄, l₄ 'and l₆ are separable. Of these lines l₄, l₄ 'is used to transmit the control command with which the main consumers 15 of the battery-powered vehicle can be locked. The line 1 serves to transmit the status data to the display unit 3 , which are to be represented thereby. As a line is l₁ provided in FIGS. 1 and 2, with a control command for blocking the charging of the battery 1 to the battery-side connector and the charger can be transferred there further to the mating connector of a (not shown in Fig. 3).

The embodiment of FIG. 3 shows the principle of the so-called "Wechselbat terie", the advantages of which are that the vehicle can continue to be used during the time required to charge the depleted battery by replacing a fully charged battery. The battery is changed frequently in very intensively used vehicles. By attaching the measuring / evaluation unit to the battery, the state data and limit values stored in the measuring / evaluation unit do not have to be checked when the fully charged battery is replaced, and the exhausted battery can be charged independently of the vehicle using the generated control commands.

In all embodiments according to FIGS. 1 to 3, the modified charger 14 can be accommodated either at an external charging station or on the battery-operated vehicle itself. The accommodation on the vehicle has the advantage that the vehicle and charger form an action unit that does not require an external charging station.

In the embodiments according to FIGS. 1 to 3, the control command transmitted via the line 1 1 for blocking the main consumers 15 can be combined with the command for blocking the charging process of the battery. This has the advantage that the user is forced to maintain the battery whenever an event has occurred during the operation of the vehicle which has led to the main consumers 15 being blocked.

The connection of the connector 11 on the consumer side to the consumers 10 , 15 of the battery-operated vehicle is not shown in FIGS. 1 to 3 in practice as shown, but via an intermediate power connection, from where the power of the battery is passed on to the different consumers . This service connection is not shown for reasons of simplification.

FIG. 4 shows a detailed illustration of an embodiment of a signal pin 22 and a signal socket 25 . These two elements are complementary to each other, so that they complement each other to form a hexagonal element. Both the signal pin 22 and the signal socket 25 have an insulating body 40 , 41 , which carries electrically conductive surfaces 42-45 on the respectively exposed surfaces, which, when plugged together, make direct electrical contact with one another and enable a control command to be transmitted. For this purpose, the line l 1 coming from the measuring / evaluation unit and the line l 1 leading to the charger 14 are used. The special shape of the signal pins 22 and the signal socket 25 also prevents batteries from being charged on unmodified chargers and thus the work processes forced by the device can be avoided.

Reference list

1 battery
2 measuring / evaluation unit
3 display unit
10 drive motor
11 consumer connector
12 battery-side connector
13 mating connector
14 charger
15 lifting motor
20 first plug socket
21 second socket
22 signal pin
23 first connector pin
24 second connector pin
25 signal socket
30 detachable plug connection
40 , 41 insulating body
42-45 electrically conductive surfaces
S switch
l₁-l₆ lines

Claims (19)

1. Device for monitoring a battery-operated vehicle and its battery ( 1 ), the device comprising:
a measuring / evaluation unit ( 2 ) for determining the status data of the battery ( 2 ) and for generating warning and / or control commands for the use of the battery ( 1 ) and the vehicle in accordance with the status data,
a display unit ( 3 ) for displaying the status data and the control and warning commands,
characterized in that
the measuring / evaluation unit ( 2 ) and the display unit ( 3 ) are housed together with the battery ( 1 ) on the vehicle. 2. Device according to claim 1, characterized in that a warning or Control command can be generated on the due maintenance of the battery indicates and / or blocks the charging process of the battery. 3. Device according to claim 1 or 2, characterized in that a Warning or control command can be generated, based on the maintenance due Indicates vehicle and / or the operation of the vehicle in whole or in part locks. 4. Device according to one of the preceding claims, characterized in that one or more of the following state data can be determined with the measuring / evaluation unit: I: current drawn from the battery and / or fed into the battery;
U, U _t : voltage of the battery (U) and / or individual battery cells (U _t );
U / U _t : ratio value;
t: time;
T: temperature of the battery and / or individual battery cells;
Q _e : amount of charge fed into the battery during a preselected period of time;
Q _a : amount of charge withdrawn from the battery during a preselected period of time;
ΔQ: difference (Q _e - Q _a );
ΔQ / Q _n : ratio, where Q _{n is} the nominal capacity of the battery;
Q _t : residual capacity of the battery; and that a control or warning command can be generated with the measuring / evaluation unit if at least one of these status data exceeds or falls below a predetermined limit value G, a single limit value optionally being dependent on the other status data. 5. Device according to claims 2 and 4, characterized in that the warning command due maintenance of the battery can be generated if ΔQ / Q _n , measured after maintenance and charging of the battery during the subsequent charging / discharging processes of the battery , exceeds a predetermined limit G₁. 6. Device according to claims 2 and 4 or 2 and 5, characterized in that the control process blocking the charging process of the battery can be generated if ΔQ / Q _n , measured after maintenance and charging of the battery during the subsequent charging / discharging Operations of the battery, a predetermined limit G₂ exceeds, where G₂ <G₁. 7. Device according to claims 3 and 4, characterized in that the warning of the due maintenance of the vehicle warning command is generated if Q _a , measured after maintenance of the vehicle during the subsequent charging / discharging operations of the battery, a given nen limit G₃ exceeds. 8. Device according to claims 3 and 4 or 3 and 7, characterized in that the operation of the vehicle completely or partially locking control command can be generated if Q _a , measured after the maintenance of the vehicle during the subsequent loading / unloading before gears of the battery, a predetermined limit value G₄ exceeds, where G₄ <G₃, wherein optionally a further control command can be generated that blocks the charging process of the battery. 9. Device according to one of the preceding claims, characterized in that a control command can be generated, the main consumer ( 15 ) of the battery-powered vehicle switches off (S) and / or the charging process of the battery ( 1 ) locks. 10. Device according to one of the preceding claims, characterized in that a control command can be generated, the main consumer ( 15 ) of the battery-powered vehicle switches off (S) and / or the charge when a limit value for U / U _{t is} exceeded or undershot the bat terie ( 1 ) blocks. 11. The device according to claim 9 or 10, characterized in that the battery-powered vehicle is a forklift and the main consumers are one or more lifting motors ( 15 ). 12. The device according to one of claims 2 or 6, characterized by a detachable cable connection between the battery ( 1 ) and the consumers ( 10 , 15 ) of the battery-powered vehicle, the cable connection being made via a pair of connectors ( 11 , 12 ), the battery-side connector ( 12 ) matches the mating connector ( 13 ) of a modified charger ( 14 ) and is connected to the measurement / evaluation unit ( 2 ), and the battery-side connector ( 12 ) has a signal connection in addition to the connections ( 20 , 21 ) for connection to the battery poles ( 22 ) with which the control command to block the charging process of the battery ( 1 ) can be transmitted from the measuring / evaluation unit ( 2 ) to the charger ( 14 ) and which blocks the connection to unmodified chargers without the appropriate mating connector ( 13 ). 13. The apparatus according to claim 12, characterized in that the counter plug ( 13 ) of the modified charger ( 14 ) has a signal connection ( 22 ) of the battery-side connector ( 13 ) matching signal connector ( 25 ) for transmitting the control command and the modified charger ( 14 ) is optionally housed on the battery-powered vehicle. 14. Device according to one of the preceding claims, characterized in that the measuring / evaluation unit ( 2 ) fixed to the battery ( 1 ) and the display unit ( 3 ) are fixed to the vehicle and the connec tion between the measuring / evaluation unit ( 2nd ) and display unit ( 1 ) via a cable with a detachable plug connection ( 30 ). 15. Device according to one of the preceding claims, characterized net that the measuring / evaluation unit a microprocessor for partial or complete determination of the status data and / or generation of the warning  and / or control commands. 16. A method for monitoring an intermittently operated battery, characterized in that
after maintenance and charging of the battery during the subsequent charging / discharging processes from a measuring / evaluating unit continuously determines the sum Q _{a of} the charge quantity removed from the battery and the sum Q _{e of} the charge quantity fed in, and from this the difference ΔQ = Q _e - Q _{a is} determined and related to the nominal capacity Q _{n of} the battery, and
a warning command is generated by the measuring / evaluation unit, which indicates the need for maintenance of the battery if the ratio value ΔQ / Q _n exceeds a preselected limit value G 1. 17. The method according to claim 16, characterized in that a control command is generated by the measuring / evaluation unit, which blocks the charging of the battery when the ratio value ΔQ / Q _n exceeds a limit value G₂, G₂ <G₁. 18. A method for monitoring a battery-powered vehicle, characterized in that after maintenance of the vehicle during the subsequent charging / discharging operations of the battery from a measuring / evaluation unit determines the amount of charge Q _a removed from the battery and a warning command from the measuring / evaluation unit is generated, which indicates the need for maintenance of the vehicle when Q _a exceeds a pre-selected limit G₃. 19. The method according to claim 18, characterized in that a control command is generated by the measuring / evaluation unit, which blocks the operation of the vehicle in whole or in part when Q _a exceeds a limit value G₄, G wobei <G₃.