[Al Skierkiewicz]

Brett et al,
This question comes up every year. I have asked the manufacturer and the Battery Institute for their recommendation in the past. Neither recommends that robot batteries be wired in parallel. As pointed out, if the certain batteries are new and always used in parallel (both charge and discharge) they may be wired this way. Large UPS power supplies and large DC current loads (like WWII submarines) use batteries in this fashion but monitor the specific gravity of the electrolyte constantly to insure that one battery will not discharge the remaining batteries.