I recently noticed that after putting my boat in the barn and hooking up the charger, one trolling motor battery
always shows charging while the other always shows charged. Always the same battery.
These trolling motor batteries were bought new at the same time and only run my 24v MinnKota Fortrex tm.
After noticing this on every single occasion, I'm wondering if this is normal or something I need to address?
The tm runs fine and I typically am only out for about 4 or 5 hours at a time.
Both batteries show full charge after a night on the charger.
What say you battery people?

Does the battery show that one battery is charging and other is fully charged as soon as you plug it in after use? If it does it would seem to me that maybe your trolling motor is only running off of one battery. Have you changed the wiring or batteries recently? Check and see if you have a switch on the trolling motor that allows you to change from 24 to 12 volts.

No, I don't have a switch. And yes, as soon as I plug in the charger it shows one battery fully charged and the other shows it is charging.
I don't think the trolling motor would even run if it only had 12V available to it. It is a 24V 80# Fortrex. It does run fine, at least it seem fine to me. Maybe a little less power at 100% than I'd prefer but, seems sufficient.
You have me thinking, 4stroke, I think I'll check the plug that the trolling motor plugs into and make sure it is getting 24V. That would make sense if it isn't. Another bad assumption on my part maybe.

also check the voltage of the charger output on that one battery and then how much voltage you have on the battery when the charger isnt plugged in. Do you have them on separate banks?

I found out a while after I got my boat that the connector was wired wrong. Instead of going from common to +12 & +24 it went to +12 & -12. TM ran fine, although it would have run better if it actually had 24 volts. Much better once I wired it right.

Stan

If you have a spare battery put it in place of the one that is charging slow. If the spare battery does the same then chances are it's the charger. If not, then it's the battery. Since the slow battery is taking a charge I wouldn't be too concerned but that's just me.

I checked the voltage at the batteries and at the plug where the tm plugs in and showing 24V.
Guess I'll check the individual banks of my charger unplugged from the batteries.
This is such a simple system, you'd think it would be simple to troubleshoot! Everything so far keeps checking out. Unfortunately, I don't have a way to check it under load and that would doubtless show me the problem, if I could.
I appreciate everyones help!

Have you tried swapping the charger leads to see if the problem follows the lead side of the charger or stays with the battery?

Back to the first. If you have a voltmeter, we're going to use it -- if not, you need to get one. After fishing and before charging, check each battery and determine the voltage at the battery. They should be apx the same since the batteries are the same age. If one is still showing fully charged around 12.75, and the other is down around 12.50/12.40, then you are only running off one battery. This could be in the trolling motor plug configuration. If both batteries are reading the apx the same, put it on the charger and wait about 15 minutes for the charger to read and start charging, then check the voltage in each battery while the charger is on. You should see apx 1.5 - 2.0V increase over the first voltage. If you do, you have a charger that is giving you a misreading.
Depending on the plug, it will either be a 3 prong or 4 prong. The prongs, if it was at one time wired for 12/24, will have a ground, 12V connection and a 24V connection. You say in another post you are getting 24V at the plug. Make sure the trolling motor is connected to the corresponding prongs that give both ground and 24V. The ground on any plug should be the "odd" prong. Hope this helps.
John