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.
When fully charged the electrolyte is mostly Sulfuric acid and it will not freeze easily, something as low as minus 60. When discharged the acid turns to mostly water and the freezing will start at much warmer temperatures, minus 10 can give a problem with a flat battery. As they get older the charge rate decreases but you should not have a freezing problem with a battery that is charged. More of a problem in cold weather is the batteries inefficiency, at minus 30 70% of the capacity is lost due to the cold. Keep the battery warm if you live in a really cold area.