Hot battery in 36v setup on charge

[WacoWildcat]

Went fishing last weekend and left my batteries plugged in as soon as I got home. Always do. Messing around in the garage today and I could feel heat coming from the back compartment. I have one battery that is very warm. Touchable by hand for sure but it’s definitely hot and I’ve never seen this happen. Seems like they’re always cool. Minn Kota 460 on board is my charger. Checked the fluid level of the battery in question and all was good. This battery was .5 volt lower than the other two in the 36v setup. Any ideas? I noticed towards the end of the day on my last trip I definitely didn’t have the power out of the ultrex like when I started but still decent. Is it toast? Batteries are interstate marine deep cycle, group 29.

[CatFan]

The hot battery is bad or at least failing.

[Fishysam]

Un hook charger, let battery cool down to the point you know it's not hot( this will take hours) swap leads, plug in but stay close, and within 30 minutes you will have a hot battery again. If it's the same battery there is a short in it, it is bad. If the problem goes to a battery the bank in the charger is having an issue. I would bet it's the battery

[billnorman1]

Check to see if the charger is putting out excessive volts, say, like over 15. Turn it off, turn on the trolling motor for about a minute on constant and turn it off and check the battery volts, if that one's low it's probably bad.
Do you have 4 batteries or three?

[tracer1]

Had the same problem a while back. Same charger also ( 460 PC). But it was my cranking battery, and I don't believe that has any bearing on the situation. My charger would not bring the battery up to charging. It would stay at 2 yellow blinking lights regardless of the hours on charge. I was told by these guys on here the same as you, & they are right. Also, mine was "maintenance free" but not really. On most of the batteries, you can peel back the top labels & check the fluid level in it. If the battery isn't too old or you caught it in time, it may be low on fluid. You can fill the cells to normal level & see if that helps. If it doesn't, get a new battery. Tried all of these solutions but mine was too far gone. If it gets too hot it can cause a fire in the battery compartment, so don't take a chance. Hope you find a sensible solution to your problem.

[WacoWildcat]

Thanks, fellas. I took fishysams advice and swapped the charger leads and the issue stayed with the bad battery. Decided to just go ahead and swap all the troller batteries and ended up with 3 new duracell 31 AGM's a couple hours later from Sam's. Ouch $$! Peace of mind now though that those interstates are out of the boat! Maybe just me but I've always ran into problems with them after 1-2 years.

[tracer1]

Replaced mine with same plus the cranking battery.