Currently running a 191 Islander, 3.0 with no kicker. Right now just have one battery running the marine radio, Hummingbird, stereo system w/ 4 speakers and a pair of 55 watt floods that are used sparingly when unlaoding the boat w motor off .......carry a spare battery on board and have a one bank charger that gets hot as heck....can barely touch the thing at times Im adding two Cannon mag 5's soon and am wondering if I should stick with the same battery, go to the spare thats not charging or run them parralel? I think if I run them together , only one bettery will be charged, correct? Anybody have any suggestions or know if this is to much cap. for only one cell, Thanks