Operation This charger is fully automatic, just plug in the batteries and it will safely charge the cells and shut off when charging is complete. This charger has two LEDs, the "Power" LED indicates 12v power is connected and the "Charger" LED indicates charge status. While you are charging the "Charger" LED is red and when the charge is complete the "Charger" LED turns green. If the "Charger" LED is flashing red, it means the pack is below 6 volts. In this case, the charger will try to charge the battery with 20mAH for 30 minutes. If the "Charger" LED does not change to solid red within 30 minutes the pack is damaged and will need replacement.