Generally, if you connect it backwards, a large current will flow, which is equivalent to a short circuit condition at the output end of the charger. Typically, chargers have current limiting and short circuit protection boards. When the current is too high, the charger activates the protection device; As for your base charger getting hot, it's because your charger keeps trying to open it after activating the protection device. This way the MOS turns on/on constantly. off at high power, so it emits heat! ! ! !
Typically this will not affect the battery for a short period of time, but if it lasts for a long time it will affect both the charger and the battery! ! So be careful when using it! !