JPH04168927A - Rapid charger for lead acid batteries - Google Patents

Abstract

PURPOSE:To recharge well an enclosed lead battery, which has been left in overdischarged state, by feeding a high current in reverse direction to the battery upon detection of overdischarged state and subsequently switching to normal charging operation. CONSTITUTION:When an enclosed lead battery 12 is left in overdischarged state, an AC voltage component is detected immediately after start of charging operation and a relay 4 functions. Consequently, relay contact 10 is switched and a current is fed in reverse direction to the enclosed lead battery 12. After sustaining that state for 10min, the relay contact 10 is switched to original state and normal quick charge operation takes place.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a rapid charger suitable for charging sealed lead-acid batteries.

A conventional quick charger charges a lead-acid battery with a large current, detects a predetermined end-of-charge voltage, and automatically ends charging, or switches to charging with a minute current (trickle charging). A problem with this quick charger is that the charging performance of lead-acid batteries that are left unused after discharge (over-discharged) is poor.

This problem is particularly serious in so-called cathode absorption type sealed lead-acid batteries in which oxygen generated from the anode is absorbed and consumed at the cathode.

In other words, a sealed lead-acid battery that has been left over-discharged has a high internal resistance, and a high charging voltage is detected immediately after charging starts, determining that it is at the end of charging, and charging is often terminated without being fully charged. Resulting in.

One way to deal with over-discharged lead-acid batteries is to charge them over a period of about 10 hours.After charging starts, a current in the opposite direction to normal is passed until the battery voltage becomes negative.
After that, there is a method to perform normal charging (Japanese Patent Laid-Open No. 62-1
760619).

Problems to be Solved by the Invention In the technique disclosed in Japanese Unexamined Patent Publication No. 62-176069, the current flowing in the opposite direction and the charging current are small, and charging takes a long time.

The problem to be solved by the present invention is to enable a sealed lead-acid battery that has been left over-discharged to be charged satisfactorily in a rapid charger that charges with a large current.

Means for Solving the Problems A quick charger according to the present invention is provided with a means for detecting that a battery to be charged has been left over-discharged, and when over-discharged neglect is detected, the quick charger is charged in the opposite direction from the normal direction. It has a function that switches to normal charging after passing a large current through the battery.

Here, rapid charging refers to a limited current IC (A) and a charging time of about 1 hour.

Function: In the charger according to the present invention, when over-discharging is detected, a large current in the opposite direction to the normal one is caused to flow through the battery.
The state in which charging can be accepted is restored in a short time, and subsequent rapid charging using a large current can proceed smoothly.

Embodiment FIG. 1 is a circuit block diagram of a quick charger according to an embodiment of the present invention. Usually, a quick charger (limited current IC (A), charging time 1
time), and when a lead-acid battery that has been left over-discharged is connected, it is detected by the AC voltage component, current is passed in the opposite direction through the IC (A) for 10 minutes, and then normal rapid charging is performed. .

The output of the power supply 1 containing an AC voltage component is connected to a sealed lead-acid battery 12 through a current/voltage control section 2, a relay contact 10, and a backflow prevention diode 11. Current/
The voltage control section 2 receives the output from the quick charge control section 3 as an input, and controls current and voltage. Further, the quick charge control section 3 operates based on the output from the charging voltage detection section 6. The relay control section 5 receives the output from the AC voltage detection section 7 and operates the relay coil 4 .

If the sealed lead-acid battery 12 has been left over-discharged, the relay coil 4 is activated because an alternating current voltage component is detected immediately after the start of charging. The relay contact 10 switches, and current flows in the sealed lead-acid battery 12 in the opposite direction to the normal direction. After this state continues for 10 minutes, the relay contact 1o switches to its original state and normal rapid charging starts.

FIG. 2 shows the charging characteristics during the above-mentioned rapid charging.

After flowing a large current (4A) in the reverse direction for 10 minutes, normal rapid charging is performed, so complete charging is possible in one hour.

On the other hand, FIG. 3 shows the charging characteristics when a conventional small current is passed in the opposite direction. The charging current cannot be increased (0.5A), and the time to flow the current in the opposite direction is 1
It takes a long time and 16 hours of charging is required after that.

The above-mentioned sealed lead-acid battery has a voltage of 4Ah-4V and an internal resistance of 300Ω after being allowed to over-discharge.

The ambient temperature during charging was 25±2°C.

Effects of the Invention As described above, the quick charger according to the present invention detects when a lead-acid battery that has been left over-discharged is connected and flows a large current in the opposite direction for a short period of time, thereby quickly charging the battery. Charging can be performed smoothly.

Furthermore, since it only takes a short time to flow a current in the opposite direction, it does not adversely affect the battery.

[Brief explanation of the drawing]

Fig. 1 is a circuit block diagram of a quick charger according to an embodiment of the present invention, Fig. 2 is a charging characteristic diagram during quick charging in an embodiment according to the present invention, and Fig. 3 is a charging characteristic diagram during conventional charging. It is. 1 is a power supply, 2 is a current/voltage control section. 3 is a quick charging control section, 4 is a relay coil, 5 is a relay control section, and 6 is a charging voltage detection section. 7 is an AC voltage detection unit, 1o is a relay contact, 11 is a backflow prevention diode, and 12 is a sealed lead-acid battery.

Claims (1)

[Claims] (1) In a quick charger that charges with a large current and finishes charging by detecting a predetermined end-of-charge voltage, it is detected that the battery being charged has been left unattended after being discharged (over-discharged). A quick charger for a lead-acid battery, which has a function of flowing a large current in the opposite direction to the normal direction to the battery and then switching to normal charging when over-discharging is detected.