2. Check whether the engine works normally, and use a multimeter to detect the voltage before and after starting;

3. Check whether the battery contact wire is in close contact with the positive and negative electrodes, and whether it is easy to pull out by gently rotating it; Or contact with too much scaling, just clean it up, someone poured it with hot water;

4. If it is an old vehicle, you should consider: prepare a spare battery. Some vehicles are equipped with anti-theft devices, especially firecrackers on holidays (or wedding days) will make the anti-theft devices ring all night, and even the best batteries will consume electricity; In addition, it may be because of the computer, so I suggest you go to the 4S shop to make a thorough investigation.