I'm going to have to take a better look at it...but I suspect it's like a standard car battery (not AGMs), inside the likes of this: http://www.walmart.com/ip/16401576?wmlspartner=wlpa&adid=22222222227000000000&wl0=&wl1=g&wl2=c&wl3=21486607510&wl4=&wl5=pla&wl6=19880599990&veh=sem .
"Inside" is a relative term, it seems, since as far as I can tell, the only "access" is via opening the rear door, and reaching into the storage under the beds (I did lift up the bed boards when inside, and did not see a way to access the battery...doesn't mean there isn't a way, just means I didn't see it on first inspection...will check this again soon.) In any case, ventilation would be questionable, I think. Unless I've missed a vent under there.
Thanks again mum. You may have saved yet another emergency room visit!
Damn, my Monday list is getting long.