JPH0618466B2 - Sealed lead acid battery charger - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealed lead acid battery charger.

2. Description of the Related Art Conventionally, batteries that have been left after being over-discharged (hereinafter referred to as "over-discharged batteries") have been a problem with sealed lead-acid battery chargers.
There is rechargeability for. This is because the charging current is difficult to flow because the internal resistance of the over-discharged battery is high. In particular, in the case of a so-called cathode absorption type sealed lead-acid battery, in which oxygen generated at the anode is consumed by the cathode active material during charging, charging with a minute current (hereinafter referred to as "trickle charging") is detected after the end-of-charge voltage is detected. Is often used.

When an over-discharged battery is charged by this type of charger, the internal resistance of the over-discharged battery is high, so that the charging voltage rises immediately after the start of charging and trickle charging occurs, resulting in almost no charging. As one of the methods for solving this drawback, as described in the specification of Japanese Patent Application No. 61-16196, which was previously filed, after applying a current in the reverse direction to the normal state to an over-discharged battery ( There is a method to return to normal charging (hereinafter referred to as "reverse charging").

Problems to be Solved by the Invention When the above charging method is applied to an actual charger, there is a problem in that it may not be recovered depending on the conditions for ending reverse charging.

As a condition for ending the reverse charge, the simplest method is to make the reverse charge time constant. But with this method,
Overcharged batteries with extremely high internal resistance have poor recoverability, and when the internal resistance is relatively low, reverse charging more than necessary increases the charging time, heat generation during charging, and life characteristics after recovery. There are adverse effects such as deterioration. An example of this is shown below.

The battery used is a sealed lead acid battery of 4V and 4Ah.
The charging characteristics when the reverse charging time is 60 minutes are shown in FIGS. 4 and 5. Figure 4 shows the charging characteristics of an over-discharged battery with an internal resistance of approximately 300Ω, and Figure 5 shows the charging characteristics when the internal resistance is approximately 1600Ω.

When the internal resistance was about 300 Ω, normal charging was started after reverse charging, but when the internal resistance was high at about 1600 Ω, normal charging was resumed, then trickle charging was started early, and charging was not performed. First The table shows the maximum value of the battery surface temperature when the reverse charging time was changed using an over-discharged battery with an internal resistance of about 300Ω. Obviously, the longer the reverse charging time, the more heat is generated. Sixth
The figure shows the cycle life characteristics after recovery of an over-discharged battery that had a reverse charge time of 60 minutes. An over-discharged battery with an internal resistance of about 10Ω has a faster capacity reduction than an internal resistance of about 300Ω and has a life of about 150 cycles.

From the above, when performing reverse charge to recover,
It is considered that a method of overcharging according to the internal resistance of an overdischarged battery is preferable.

Means for Solving the Problems The present invention solves the above problems, and only an over-discharged battery having a high internal resistance is subjected to reverse charging according to the internal resistance, and the voltage of an AC component included in the charging voltage. There is a certain value A
In the above case, the reverse charging current is caused to flow until the voltage of the AC component included in the reverse charging pressure becomes a certain value B or less, and the voltage of the AC component included in the charging voltage is lower than the constant value A and is constant. When the value is larger than the value C, a current is supplied in the same direction as the normal charging, and a means for performing the normal charging only when the voltage of the AC component included in the charging voltage is smaller than the constant value C is provided. To do.

Action The present invention has the above-mentioned characteristics, so that it is possible to perform reverse charging depending on the internal resistance when the internal resistance of the over-discharged battery is high, and to recover by normal charging when the internal resistance is not high. Becomes

This is because when the internal resistance of the over-discharged battery is high, the AC voltage component included in the charging voltage increases, and when the over-charged battery is reverse-charged, it is included in the reverse charging voltage as the reverse charging progresses. If the internal resistance of the overcharged battery is not high, it is possible to recover by normal charging by passing a current in the same direction as normal until the AC voltage component contained in the charging voltage decreases. It is an application of this.

Therefore, according to the present invention, when an over-discharged battery having a high internal resistance is charged, it is possible to recover from normal charging after reverse charging until the AC component included in the reverse charging voltage becomes a certain value B or less. is there. When an over-discharged battery with a low internal resistance is charged, a normal current is applied until the AC voltage component included in the charging voltage reaches a certain value C or less, and then normal charging is restored. It is possible.

Embodiment One embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a circuit diagram of a charger using the present invention. During normal charging, trickle charging is started after the end-of-charge voltage is detected. When the voltage detection unit 5 detects the end-of-charge voltage, the control unit 4 operates to control the current control unit 3 to start trickle charging by the resistor 2. .

The reverse charging control unit 6 controls the charging of the over-discharged battery, and controls the charging current and the relay by the outputs of the three AC voltage detecting units. The first AC voltage detector 10 whose detection voltage is A and the second AC voltage detector 9 (A> C) whose detection voltage is C detect the AC voltage component during charging through the capacitor 15 and the resistor 11. The third AC voltage detection unit 8 whose detection voltage is B includes a capacitor 14 and a resistor.
Through 12, the AC voltage component included in the reverse charging voltage is detected. When the AC voltage component at the time of charging is A or more, the reverse charge control unit 6 causes a current to flow through the coil 7 of the relay until the AC voltage component included in the reverse charge voltage becomes B or less.
And the control unit 4 is controlled to flow a reverse charging flow. When the AC voltage component at the time of charging is C or more and A or less, the reverse charge control unit 6 controls the control unit 4 to flow the charging current until the AC voltage component at the time of charging becomes C or less. By this operation, the overcharged battery having a high internal resistance is reversely charged, and the internal resistance becomes high, and in the case of an overdischarged battery, it is possible to recover without performing the reverse charging.

In FIG. 1, 1 is a transformer rectifier, 16 is a diode, and 17 is a sealed lead-acid battery. Charging characteristics when using a sealed lead acid battery of 4V and 4Ah are shown in FIG. 2 and FIG. The end of charging detection voltage is 4.9V, the first AC detection voltage A
Is 1.0 V ^PP , the second AC detection voltage B is 0.5 V ^PP , and the third AC detection voltage C is 0.5 V ^PP . Fig. 2 shows the charging characteristics of an over-discharged battery with an internal resistance of about 1600Ω. After 90 minutes of reverse charging, normal charging begins. Fig. 3 shows the charging characteristics when the internal resistance is about 50Ω.
It takes 30 minutes to charge normally.

EFFECTS OF THE INVENTION As described above, according to the present invention, the AC voltage component included in the charging voltage, the AC voltage component included in the reverse charging voltage, and the internal resistance are increased, and the overcharged battery can be recovered without performing the reverse charging. In the case of an over-discharged battery with a high internal resistance, reverse charging is performed until the AC voltage component contained in the reverse charge voltage falls below a certain value. It is possible to recover without charging. Therefore, the industrial value is extremely great in that the reverse charge can be minimized.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIGS. 2 and 3 are charging characteristic curve diagrams when the charger according to the present invention is used, and FIGS. 4 and 5 show reverse charging time. FIG. 6 is a characteristic curve diagram showing the charging characteristic when it is constant, and FIG. 6 is a characteristic curve diagram showing the cycle life characteristic after the reverse charge recovery. 3 is a current control unit, 4 is a control unit, 5 is a voltage detection unit, 6 is a reverse charging control unit, 8 is a third AC voltage detection unit, 9 is a second AC voltage detection unit, and 10 is a first AC voltage detection unit. , 17 are sealed lead-acid batteries

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akio Komaki 2-1-1, Nishishinjuku, Shinjuku-ku, Tokyo Shin-Kindo Electric Co., Ltd. Examiner Akira Suzuki

Claims (1)

[Claims] 1. When the voltage of the AC component included in the charging voltage is a certain value A or more, the voltage of the AC component included in the charging voltage in the opposite direction to the normal charging current is changed. The voltage of the AC component included in the charging voltage is lower than the certain value A and is given a certain value C
When it is larger, a current flows in the same direction as normal charging, and a means for performing normal charging only when the voltage of the AC component included in the charging voltage is smaller than the constant value C is provided. Lead acid battery charger.