I am possibly having a prob. With mt on board 3 bank charger. The crank is good therek battery is showing 12.76 volts So good there. The problem is bank 3[ trolling battery shows like 7.8 v. other troll. battery is like 12. 55v. I had gharger plugged in over night. Red light says connection prob. Well cleaned both troll. batteries terminals and charger terminals just to elimanate, any thing corroded or loose. Well let's hear some ideas. I think Bad battery/ bank 3 HELP!!!

Too low for charger to recognize. Put a manual charger n that one battery and see if that fixes your issue.

Thanks i was thinking the same,?? 10amps for 1/2 hr.???

if you have a start assist on the charger use it for about 10 mins. then try the on board. just need to zap them up to about 10.5v

I had a similar situation earlier this year my wet cell Group 27 deep cycle trolling motor bateries wouldn't charge up (they were two year old Interstates) so replaced them with the Duracell Group 31 AGM's. The starting battery was good at the time charging volts etc. Went out to the shop a week later and bank 3 (starting battery) was blinking red so turned off charger and disconnected cables and checked battery and low and behold it was at 2 volts. Should of known better because all of the old batteries were the same age. Mine is the MK-330-D charger.

thanks guys may try up the amps charger has a 50amp. position

Run a slow ch arge

just for about 10-15 mins. it won't take long if the battery is good. just brings it up enough to be recognized by the onboard.

Thanks everyone, forhelp . after checking & cleaning terminals & cables, i put battery on 50 amp for 15min. checked it for volts about 7hrs later. Less than 7. Well i knew they were 3 + years old. Went to Sam's bought 2 group 27 dc batteries. Plugged in charger at 7;15pm shows still charging at 9pm BUT no red light.. should be good.??

If you ever wonder if something is up with a particular bank of your charger, move the two charging leads to another battery - actually swap them completely. If the problem stays with the battery that the leads were connected to, it's the battery. If the problem moves to the other battery, the problem is the charger.