Just bought a 96 nitro. Guy said he put a new battery (from advance auto, deep cycle marine with 550 cca) in for the outboard (70 hp force, believe 1996). Also have a MK V2 powerdrive (45# thrust) with copilot on separate battery (from tractor supply, Stowaway deep cycle marine battery, 105 amps, 27DC), and a MK210 on board charger. When you plug the on board charger up, red lights come on and it says "check connection" (I believe). From best I can tell, everything is wired properly. Left plugged up as is overnight, and both trolling battery and outboard battery dead the next day. Took batteries to get tested and they said they could both be recharged. So we charged both batteries overnight with a battery charger (not on board MK) similar to car battery charger. Put the trolling battery in and it ran great right off. Checked it the next day and trolling motor was not working, battery dead again. When putting the outboard battery in, it didn't work at all so tried recharging and it couldn't get any charge at all (suppose it's dead, getting it tested tomorrow). So my question is, do you suppose it's just a bad battery, both bad batteries, or is something sucking the life out of both of them. Also, are the batteries big enough for the job, and should I get a cranking battery for the outboard? Thanks for everyone who helps!
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