The battery is sufficient, but two red lights are under load (under-voltage light, over-current protection light is on, and the motor is off.) 

1. The output voltage of the charger is low: replace or repair the charger;

2. The battery charging time is short: extend the recharging time Charging time;

3 The capacity of the battery pack or one of them decreases: replace the battery;

4 The electrode is damaged or in poor contact: replace or repair the electrode.