Brother you are right in car the batteries are placed in very hot place, but that is well ventilated. but in the car batteries are not in use all the time, battery is only use for the initial startup for some seconds and are only used up-to 30 to 40% of battery. but in our home usage, we are using the batteries up-to 80 to 95% of battery.
As per my recommendation we have to use one bracket fan for the batteries and should use up-to 40 to 50 % of battery and use Distilled Water not AC water or any other. and for our country temperature we should use the led acid batteries because they can bear the hot temperature but the dry battery should have very good temperature for the best usage.