1. The battery cannot be charged or is insufficiently charged. 

1 End of battery life: replace or repair the battery;

2 The fuse in the fuse inside the battery is broken: replace the fuse;

3 The contact between the battery fuse and the fuse holder is poor: adjust the position of the two to make good contact, or replace the fuse;

4 Charge No output voltage or low output voltage of the charger: replace or repair the charger; 

5 The charger is in poor contact with the AC 220V power supply: re-plug the power supply;