when I put GC batteries in mine I measured the size of each one, then measured the space and opening I had to get them in. granted I was putting them into an older one that wanst made for more than a car battery so I had to turn the battery compartment into a small storage compartment and use the storage compartment for my batteries. the deciding factor on the batteries was the door opening. the 210AH batteries left me 3/4" of clearance through the door, the 220AH set would only leave me 1/8" and the 235AH were bigger than the door. I also bought a watering kit as although the space was biger inside there just want enough room to get a turkey baster or measuring cup in there to add water, or your head to see how far it was down. the watering kit works awsome, I just plug the pump extension into the harness put the end in my distilled water and pump it till it wont pump anymore. fills the batteries perfect and takes two min. so now I do this every time I am getting ready to leave instead of the twice a year check I do on the 5th wheel. I am buying a set for the 5th also I like them so much.
Steve
