1. The fuse in the battery is broken. In this case, only the fuse inside the battery can be replaced; 2. Poor contact, including many aspects, such as poor contact between the safety tube and the safety seat, poor contact between the plug and the socket, poor contact between the charger and the power supply, etc., will affect the normal charging of the electric vehicle, resulting in the battery not being charged or fully charged; 3. Poor contact of the plug-in in the battery: the main reason is that there is a problem with the connection between the positive and negative electrodes of the battery, so you can try to plug it in again or change the wire; 4. The service life of the battery exceeds the service life: the normal service life of the battery is about 5 years, but if there are often incorrect charging methods, the battery will be scrapped in advance, and the solution is to replace the battery.