An interior door does not have to withstand extreme weather changes. Interior and exterior doors are not the same product sold under different labels. The construction of each is different, with exterior doors given special treatment to stand up to the elements and frequent use.
The charging of lead-acid batteries can be hazardous. However, many workers may not see it that way since it is such a common activity in many workplaces. The two primary risks are from hydrogen gas formed when the battery is being charged and the sulfuric acid in the battery fluid.
Try that and see if it fixes the problem. When my battery is charging I've never noticed that it gets hot, so I wouldn't be concerned about that part. If you have the same charger as I do and you have the single size lithium ion battery, when it's charging properly you will see a steady red light and one that flashes. When the battery is fully charged you'll see a green light and a red light. The steady red light is just telling you that the charger is plugged in.