Battery issues

[mrbraq]

My batteries are new, but after coming back from a repair, 1 doesn't seem to be holding a charge. Any suggestions on what should I do next?

2 batteries are fully charged. Bank 1 is at 25%

[Joe4d]

disconnect everything from that battery, let it charge over night then take it to an auto parts chain and ask them to load test it for you.
Either battery is bad or you have too much load on it.. That too much could be something like a partial ground or something else draining battery.
First step though is always the power supply.. So verify the battery .

[catdude28]

First thing to do is to make sure it isn’t the charger. Do a bank swap and see if the issue follows the bank or the battery.

[Jonestrollingmotor]

At 25% it may be too low for the charger to recognize and turn on to charge. Disconnect the battery, use another charger to charge it and see if it takes a charge. If it does, and holds, then swap the banks with another battery and after turning the onboard charger on, use a voltmeter and verify all the banks are reading apx 2V above the battery voltage.
John

[billnorman1]

They might have removed the battery to work, and forgotten to hook one or more of the charger leads to it. Charger leads aren't that big they might (horrors) have broken one off.
Count the leads on all of the trolling motor batteries, should be an even number.

[mrbraq]

To close this out for future searches...

Turns out the key was left in the On position, draining the cranking battery completely, which I didnt consider. After charging it again overnight, it held a charge.

First boat owner mistake - I didnt realize leaving it On would draw that much power, even when nothing is in use.