JPH0618468B2 - 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 charge 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. FIG. 6 shows the cycle life characteristics after recovery of the over-discharged battery which was recovered after the reverse charge time was 60 minutes. Internal resistance is about
In the case of a 10Ω over-discharged battery, the capacity decreases faster than when the internal resistance is about 300Ω, and the battery has a life of about 150 cycles.

From the above, when performing reverse charge to recover,
It is considered that a method of performing reverse charging according to the internal resistance of the over-discharged battery is preferable.

Means for Solving the Problems The present invention solves the above-mentioned problems, and only an over-discharged battery having a high internal resistance performs reverse charging according to the internal resistance.
When the AC voltage component included in the charging voltage has a certain value A or more and the DC voltage component has a certain value B or more, reverse charging is performed until the AC voltage component included in the reverse charging voltage has a certain value C or less. When the AC voltage component included in the charging voltage is equal to or higher than the constant value A and the DC voltage component is equal to or lower than the constant value B, a current flows in the same direction as the normal charging direction, and the AC voltage component included in the charging voltage is It is characterized in that it is provided with means for performing normal charging only when the value is equal to or less than the constant value A.

Action The present invention has the above-mentioned characteristics, and therefore, it is possible to perform reverse charging according to the internal resistance only when the internal resistance of the over-discharged battery is high, and to recover by normal charging when the internal resistance is not high. is there. This is because if the internal resistance of the over-discharged battery is high, the DC component contained in the charging voltage will be large, and if the internal resistance is not high, reverse charging will be performed until the AC voltage component contained in the reverse charging voltage becomes small. It is possible to recover by doing, and if the internal resistance is not high, it is possible to recover by flowing current in the same direction as normal until the AC voltage component contained in the charging voltage decreases.

Therefore, according to the present invention, when an over-discharged battery having a high internal resistance is charged, it is possible to perform reverse charging until the AC voltage component included in the reverse charging voltage becomes a certain value or less, and then recover.

Also, when an over-discharged battery that does not have a high internal resistance is charged, it is possible to recover it after applying a current in the same direction as normal charging until the AC voltage component contained in the charging voltage falls below a certain value. is there.

Embodiment An 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 first end voltage detection unit 5 detects the end-of-charge voltage, the control unit 4 operates and controls the current control unit 3 to control the resistance 2. The trickle charging is started.

The reverse charge control unit 6 controls the overcharged battery when it is charged, and controls the charging current and the relay by the outputs of the two AC voltage detecting units and the one voltage detecting unit. The 1 AC voltage detection unit 9 whose detection voltage is A detects the AC voltage component generated in the sealed lead-acid battery 17 during charging through the capacitor 13 and the resistor 12, and the 2nd AC voltage detection unit 10 whose detection voltage is C is An AC voltage component included in the reverse charging voltage is detected through the capacitor 14 and the resistor 11, and the second voltage detection unit 8 whose detection voltage is B detects the DC component included in the charging voltage.

When the AC voltage component at the time of charging is A or more and the DC component is B or more, the reverse charging control unit 6 causes a current to flow through the coil 7 of the relay until the AC voltage component included in the reverse charging voltage becomes C or less, and contacts of the relay. 15 is switched and at the same time the control unit 4 is controlled so that the reverse charging current is supplied. When the AC voltage component during charging is A or more and the DC component is B or less, the reverse charging control unit 6 controls the control unit 4 to flow the charging current until the AC voltage component during charging becomes C or less. By this operation, it is possible to reverse charge an over-discharged battery having a high internal resistance and to recover it without performing a reverse charge when the internal resistance is not high. In FIG. 1, reference numeral 1 is a transformer rectifier, and 16 is a diode.

Charging characteristics when using a sealed lead acid battery of 4V and 4Ah are shown in FIG. 2 and FIG. The end-of-charge detection voltage is 4.9
V, the first AC detection voltage A is 0.5V ^PP , the second AC detection voltage C is 0.5V ^PP , and the DC component detection voltage B is 5.6V.

Fig. 2 shows the charging characteristics when the internal resistance is about 1600Ω.
After reverse charging for a minute, normal charging is started. Fig. 3 shows the charging characteristics when the internal resistance is about 50Ω, and the normal charging is started about 30 minutes after the start of charging without going into reverse charging.

EFFECTS OF THE INVENTION As described above, according to the present invention, in the case of charging an AC voltage component and a DC voltage component included in a charging voltage, an AC voltage component included in a reverse charging voltage, and an over-discharged battery having a low internal resistance, the reverse Paying attention to the fact that it can be recovered without charging, it is possible to perform reverse charging according to the internal resistance when the internal resistance is high, and to recover without performing the reverse charging when the internal resistance is low. Therefore, the industrial value is extremely great in that the reverse charge can be suppressed to the necessary minimum.

[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 first voltage detection unit, 6
Is a reverse charge control unit, 8 is a second voltage detection unit, 9 is a first AC voltage detection unit, 10 is a second AC voltage detection unit, and 17 is a sealed lead acid battery.

 ─────────────────────────────────────────────────── ─── 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 AC voltage component included in the charging voltage has a certain value A or more and the DC voltage component has a certain value B or more, the current in the direction opposite to the normal is changed to the charging voltage in the direction opposite to the normal. It flows until the voltage component contained falls below a certain value C, and when the AC voltage component contained in the charging voltage is above the certain value A and the DC voltage component is below the certain value B, it is in the same direction as the normal charging direction. A sealed lead-acid battery charger, comprising means for supplying a current and performing normal charging only when an AC voltage component included in a charging voltage is equal to or less than the constant value A.