thanks for the link, thanks for help,ideas.
I have already purchased batteries. i have a three stage charger with float in my travel trailer,(bummer that it,s not 4 stage) these batteries are for my truck camper, and I purchase of a PD 9245c (pendent too) charger for truck camper and only one of the batteries will fit in the battery compartment, I place the other one on the floor of the truck camper. one battery runs the fridge and such, The other battery will sit on the floor that one to my television and computer, I know nothing about truck camper charging to camper from truck,,, worry that the truck camper will drain the pickup truck truck battery, so that's why I have two. I believe the old charger fried my yellow top battery, because it has solid 13.6 volt Charge all the time, brand name of it is magnetek. it,s very old one, truck camper is 2003 model year.