What started this thread was a question regarding chassis batteries. That in turn prompted a discussion relative to heat because there is no heat compensation on the alternator or any way to control ambient temps.

I would be very interested in having someone whose AGM or Gel Cell batteries are located in an enclosed compartment rig up some way to measure and record temperatures, especially in the summer in the southwest. When I was involved with Interstate and their new Gel Cell batteries the temps in the engine area where my battery racks were exceeded 130 degrees F on a 60 degree day. This despite the fact the door was slotted, the floor was open and the bus movement caused a lot of air flow.

Despite temperature compensation I would expect battery compartments not vented to the atmosphere such as those enclosed for aesthetic purposes or hidden from view on warm days are also getting warm. What I don't know is the definition of warm. I do know 130 was unacceptable.