1. Charge. If after charging for a period of time, the battery voltage can be restored to more than 12V, indicating that the battery is no problem, continue to be full can be used normally, otherwise proceed to the next step;
2. Activation. For the battery that is not charged, it can be activated by charging and discharging the battery with a larger charging and discharging current (more than 2 times the current in normal use). If the battery voltage can be restored to more than 12V after three cycles, it indicates that the battery is successfully activated and can be used normally if it continues to be full.
3, if the battery activation is not successful, sorry, it is time to replace.
Car battery charging method:
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1, turn off the engine, remove the battery from the car;
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2, find a ventilated and cool place, open the ventilated cover on the battery, some of the lid is screwed on, the opposite direction can be screwed off, some need to use the screwdriver to pry open, if it is maintenance-free battery, do not need to open the lid;
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3. Hold the charger red pliers to the positive electrode of the battery with a plus mark, and the black pliers to the negative electrode of the battery with a minus mark;
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4, because it is a used battery, it should be slowly charged when charging, to adjust the gear to 2, select 12 volt power supply, the size of the current can be seen from the ammeter;
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5, plug in the charger power, turn on the switch, charge the battery, the general charging time should not exceed 12 hours.