Premature Capacity Loss (PCL) Repair Methods
Ⅰ. Characteristics of premature loss of capacity
When low antimony or lead-calcium is the grid alloy, the capacity suddenly drops in the early stage of battery use (about 20 cycles), which makes the battery ineffective. Almost every cycle the battery capacity will drop by 5%, and the rate of capacity drop is faster and earlier. In the past few years, the batteries of the lead-calcium alloy series often appeared inexplicably with a decrease in the capacity of several batteries. Analysis of the positive plate did not soften, but the positive plate capacity is extremely low.
Ⅱ. The solution to the cause of this phenomenon is found
The tin content of your own positive plate. For deep cycle batteries, a tin content of 1.5% to 2% is basically used;
Increase the assembly pressure;
The acid content of the electrolyte should not be too high.
Ⅲ. Pay attention to
Avoid the initial charging current being too low continuously;
Reduce deep discharge;
Avoid overcharging too much;
Do not increase battery capacity through excessive active material utilization.
Ⅳ. Recovery of batteries with early capacity loss
The first is to increase the initial charging current to 0.3C~0.5C, and then use a small current to supplement the charging;
Secondly, it is best to store a fully charged battery at 40℃～60℃; discharge it to 0V with a small current less than 0.05C. Discharge will be slow after the battery voltage reaches half the nominal voltage. Repeated this several times, the capacity of the battery can be restored.
Ⅴ. Notes
Be sure to identify if the battery occurred in the first 20 cycles. For a battery with a capacity drop in the middle and late stages, this method can only damage the positive plate of the battery, resulting in softening of the positive plate.
The lead-calcium alloy series of batteries often appear inexplicably. The main reason for the decrease in the capacity of several batteries is the imbalance of the battery. The lead-calcium alloy series of batteries have a higher sufficient voltage. Generally, the charging voltage of a 12V battery is greater than 16V.
When the voltage of the charger is too low, it is easy to cause battery imbalance. The phenomenon happens like this. When a group of batteries are used together, the self-discharge of each battery cannot be absolutely equal. The battery with a little larger self-discharge cannot be fully charged every time the constant voltage charger is used. If there is no gassing reaction in the electric grid, the relative area of the electrode plate in contact with the electrolyte is large, and the self-discharge is large.
The grid with small self-discharge can be fully charged every time. When it is fully charged and then overcharged, a gas evolution reaction occurs, gas is generated, the contact surface of the electrode plate is relatively reduced, and the self-discharge is reduced. At the same time, the charging voltage increases, and the charger is turned off. As a result, the self-discharge is small, and the self-discharge of the high-voltage grid becomes smaller and smaller, and it can be fully charged every time, while the self-discharge of the large self-discharge cell becomes larger and larger, and it cannot be fully charged each time, and the more the battery is used, the smaller the self-discharge is. If it is not enough for a long time, it will vulcanize and fail.
The root of the problem is that the constant voltage charger cannot be used. If the constant voltage charger is used, the above phenomenon will occur if the constant voltage value is too low. If the constant voltage value is too high, the battery will be thermally out of control. Multi-stage chargers with various voltages. And at the end of charging, there should be a small current long charge with a higher voltage and a smaller current to balance the battery power.
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