The main reasons for the heating of electric vehicle batteries during charging are as follows:
1. Battery aging: With the increase of usage time, the chemical properties of the battery will gradually deteriorate, the internal resistance will increase, resulting in the generation of more heat during the charging and discharging process. The aging of batteries may also cause the electrolyte to dry up, resulting in internal short circuits and further exacerbating the heating phenomenon.
2. Charger issue: If the charger malfunctions, such as output voltage being too high or too low, improper charging limit voltage setting, etc., it may cause the battery to overheat during the charging process. If the charger does not have pulse function or negative pulse polarization elimination function, it may also be unable to maintain constant voltage in the later stage of charging, causing the battery voltage to exceed the allowable value and leading to battery heating.
3. Charging environment and usage habits: Charging in a high temperature environment may increase the working temperature of the battery, which may cause overheating. Long charging time, mixing chargers with non original or non same model current and power, and long-term disuse of batteries leading to plate vulcanization are also common reasons for battery heating during charging. Charging for too long can lead to overcharging of the battery, excessive internal resistance, reduced conversion efficiency, and excessive heat generation. Mixing chargers may cause battery heating due to voltage mismatch. If the battery is not used for a long time, the sulfides on the electrode plate will affect the charging efficiency of the battery and also easily cause heating.