I tried to help him, but he is a very stubborn guy !! I told him Id ask the experts.He is running 3 batteries, 1 Interstate true Cranking battery (800 or850 CCA) and 2 Interstate group 27 deep cycle TM batteries. (Pantera III with 200 Pro XS with a 36v Motor Guide)In 2 tournaments, his boat would not start after fishing and not cranking the engine for approx. 5 hrsMy advise — poor set-up as a true cranking battery has no place in that setup and to run 4 batteries if he wants a 36 v system , or get 3 group 31 dual purpose batteries to try and support that load.His Plan– get 1 dual purpose battery goup 31 as the cranker (likd a Sears PM1) and leave the to TM batteries and run it like thatMy guess– not long before disaster strikes again Any comments or suggestions appreciated. Thanks, Oh, did I mention hes on the tight side!!