Answer: The reasons for the battery discharge heat are:

(1) Cause of discharge heating: the discharge is too fast, it may be that the battery capacity is small, and the discharge current exceeds 0.5C for a long time. It is emphasized here that although the battery consumes a certain amount of power after a short journey, after the battery is stationary, the battery has a recovery process, and the electrochemical process of the plate continues, so the voltage will rise, but it does not mean that the capacity will rise. In contrast, during long-distance driving without stopping on the road, the electrification of the plates and the consumption of electrical energy occur simultaneously. There are three situations:

① When the rated voltage of the motor is low, the battery capacity is small, the operating current is too large, the voltage will drop sharply, and the capacity will be exhausted quickly, which is most detrimental to the battery.

② The electrochemical reaction speed of the battery can only maintain driving, and the battery has no chance of recovery and respite. It is often charged and discharged for the whole cycle, and it will be over-consumed if you pay little attention. When facing upwind and uphill, the power consumption is very large, forcing the battery plate to respond sharply. The high heat of the battery case will damage the battery and shorten the life, indicating that the capacity is not surplus.

③ It is ideal that the electrochemical reaction speed of the battery can calmly supply enough electric energy. The battery case has no abnormal heat, indicating that the battery capacity is surplus.

It should be noted that the battery case is obviously hot, and the internal battery itself is even hotter.