This is absolutely normal, during the charging process your Evo-Tec On-Board Charger will create heat and may become warm to the touch. This does not indicate an issue with the battery or charger and will not damage either item.
A waterproof cooling fan is installed outside the charger. When the bottom aluminum stretched plate’s temperature is higher than or equal to 50℃ ±5℃ (122°F ±9°F), the fan will work. When the bottom aluminum stretched plate’s temperature is lower than or equal to 40℃ ±5℃ (104°F ±9°F), the fan stops working.
If the Evo-Tec On-Board Charger reaches a temperature that is too high for proper function it will engage the Over Temperature Protection Function. When the temperature of the radiator inside the charger is more than or equal to 80℃ ±5℃ (176°F ±9°F), the charger will automatically reduce the output current for overtemperature protection. When the internal temperature drops, the charging current will gradually increase and finally recover to max output.