We replaced the puny, group 24- 12v battery that came with our 2012 Cougar with 2 - 6v golf cart batteries from Costco. IIRC, they were around $89 each in November of 2011. Traded the Cougar in November of 2017 and those batteries were still good. When we got the new trailer home, immediately went to Costco and bought 2 - 6v golf cart batteries from Costco. I think they cost me something like $96 each. Good bang for my buck
