Trolling Battery Question

I have 12/24 set up. Trolling motor 19 yrs old. I have three bank onboard charger that is plugged in unless fishing. Batteries are two years old this Tuesday. Go to lake run on calm day, all day rigging, lite use bumping to move slowly, all well. Windy day, running on high 12 or lower 24 after a few hours on the lake less and less power. Tie up or drag chain let it set awhile and more power back, not seemingly as much as at start. Come home check with volt meter, 12.11 and 12.8 in the other. Put meter on battery and run trolling motor voltage drops to 7-8 volts. Let off and voltage back up. Plug charger in, leave overnight, shows full charge for all. Voltage is 12.87 run trolling motor, voltage drops to 12.5 or so. About the same on 24v side drops to 23.9 while running. Took one of the batteries out and checked fluid all full, checked with Hydrometer and all cells are in the fair range, out of bad, fair, good. I do not know how accurate they are, never used one before. Is there a true way to load test a deep cycle battery?

While having the problem my thought was the trolling motor was drawing to much current, getting hot, let it cool and works again.

Now thinking the batteries are just getting weak. I just thought that the batteries would show a lower voltage on a standby reading. Did not get to check voltage while having the problem, probably 3 hours after having problem voltage reading was taken. Would the voltage come back up just sitting if they were down 3 hours before? But lack the amps to run the TM! I think I am going to be buying battery's. I have Interstate now, any thoughts on better ones that might last longer, or is this all you can expect?
Thanks for reading, and any thoughts are appreciated! Mark

with out a second thought your trolling motor is the problem, may need to replace the brushes, or check to see if there is an obstruction dragging the prop down... a 19 year old trolling motor is almost unheard of these days.... check all connections, clean terminal and ends of cables, double check all your wiring. sound like you said way to much current draw, a short in the wiring can cause a voltage drop,and no smoke, you may have a bare wire touching metal along the run.

Brand is the ford/chevy debate everyone will have their own name to drop, truthfully I don't see that much difference. Newer technology trolling motors will have more thrust per amps drawn but is it possible for a trolling motor to become less effective over the years? Could be but I'm betting batteries are your culprit. My belief is that the number of recharge cycles factor in and that if you have to replace batteries often its a sign you are getting to fish a lot, use it as a badge of honor and be proud. By the way at present rate mine are going to last me a long time.

One way to improve it may be to replace the wiring from batteries to T.M........the bigger the better. Some older set ups used 10 ga wire, but these days I think 4 ga is recommended.

If you haven't already, you may want to post this thread to the main forum....electronics and trolling motors

Take your batteries to a place that sells them and they should be able to do a load test.

I would check the TM draw while it's under a load (pulling the boat). Without the load on it, your reading will be off. If your batteries check out good with a load tester, I say TM. JMO without testing myself. 2 years isn't much on well maintained batteries. I assume that you charge them as soon as you get home or back to camp with them? If you do they should last 4-6 yrs easy, if not, 2-3 years is about it!!!!!


BRM 870-635-0202


BRM 870-635-0202

I do appreciate the replies! Trolling motor is old Johnson, they are good motors, have thought about new but still like the old one. Is there anybody that works on these motors? I actually have an old power head for it I could get rebuilt. Preferable around KC or Truman or anywhere in between. I have replaced all the switch's on the pedal. Wiring is fine and connections are fine. I will take my volt amp meter next time fishing with me and see what the situation is. (I hate to take tools fishing!!!!!) Maybe it will work fine if I take some tools!!!
I have been researching some and found several things that say the batteries are good for x number of charge and discharge cycles and thats it! Kaz don't tell my wife but that might just be the problem! I have been blessed! Thanks

You could give this fellow a call Jerry's Trolling Motor Repair | Kansas City Metropolitan Area, Missouri & Kansas . His site indicates he's authorized for MinnKotas and Motor Guides repairs. If he can't work on yours he could probably steer you in the right direction for getting yours worked on. He is just a one man shop so he may not be speedy but I've certainly been happy with his work on my MinnKota a couple of times it needed some work.

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Originally Posted by LBM

You could give this fellow a call Jerry's Trolling Motor Repair | Kansas City Metropolitan Area, Missouri & Kansas . His site indicates he's authorized for MinnKotas and Motor Guides repairs. If he can't work on yours he could probably steer you in the right direction for getting yours worked on. He is just a one man shop so he may not be speedy but I've certainly been happy with his work on my MinnKota a couple of times it needed some work.

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Thanks! I will give him a call in the morning!

Had simular sounding problem mine is a 93 it was one of my deepcycle batts. I have really good luck with AC Delco 27 series.

If you are drawing down your voltage that much when you are out of the water it means you are drawing much more current than you should be. Brushes in the motor would be my first bet. A dirty armature or a wet armature could also be the problem. If it got hot, you may have shorted windings in the armature. It doesn't sound like a batter problem to me.

I bought 2 Maxx batteries from Wal Mart last year and had to have both of them replaced already. Hard to say if it's the motor or the wiring, I worked for Tracker Boats years ago and have a trolling motor harness laying around some where that your welcome to if that is the problem. It does not have the breaker box on it anymore but I think there is enough wire for you boat.. Good Luck!

Brian it was good to talk with ya the other day. Hope ya got your livewell as full as you wished for! I think the wiring is fine, I am going to get new batteries tomorrow, I need a spare for my sprayer and several electric fences anyway! If that don't fix it I will work my way through the components. I will let ya know if I get to the wiring! Thanks Mark

Sounds like the TM or wiring to me. Had various problems over the years, sometimes TM, sometimes battery and once a blown fuse from charger to battery. Have also heard from a couple people that deep cycle batteries need drawn down to dead-then charged back up or they get a zone. I got an old car headlight with alligator clips. Two times each year I hook the headlight to the batteries and lay it on garage floor to disharge the batteries to dead. Takes days. Then charge em back up. Can usually get 3 somtimes 4 years out of em. Anybody else heard of this or am I a fool again?

I left right after you all did Friday, I had my limit but only a few over 11 inches. I had a trolling motor problem myself Friday, I was being stupid going from the back of the creek to the mouth at full speed and hit a stump, the trolling motor shaft got bent clear under the boat and a rod fell in the lake which I was lucky and bragged the end of the handle on the way down. The Minn Kota Maxxum 80 says the shaft is unbreakable and I think I put it to it's limit, the only thing that happened was I broke a blade of the prop.
I went to Wal Mart and bought a prop for 25 bucks which I thought was kind of high, got home and the prop shaft was to small so I got online and found the prop that fit my motor and it cost 40 bucks!!!!!!!!banghead. It's the same size, shape and brand that I bought from Wal Mart but it has a half inch hole!!!!!!!! what a rip off.:mad: OK I'm done with my rant, it was my stupidity the started it all. :crazy:

Brian sorry about your little problems there! Like they say if ya ain't using it won't break. I like using it!

It's not totally unbreakable but it's so much better than a steel shaft that it isn't funny.

I wouldn't do that.

Had that exact problem just the other day...well sounds the same. Noticed the trolling motor was lagging a bit just didn't think too much about it until it wouldn't even pull the boat in high gear after an hour or so. Drifted around for a few minutes and it would haul butt for about 5 seconds then dead again. I knew I had help because my uncle was in his boat fishing close by so I went ahead and switched my starting battery over to my trolling motor and it worked fine the rest of the day and still had enough juice to start the big motor. Someone else mentioned the load.. There is a difference between your volts at rest and your volts while under load. I don't understand it so am not going to try to act like I do, but I know there is a difference.... my guess is your battery or batteries are done for.....I don't know if there is any one battery brand better than the next as I've had them both go bad and both last.

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Originally Posted by Bigby

The Minn Kota Maxxum 80 says the shaft is unbreakable and I think I put it to it's limit, the only thing that happened was I broke a blade of the prop.

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Let me chase a rabbit,
If you are trying to teach the wife to run the trolling motor and she ask "Is that pulled back enough?" Don't just answer her with a "its ok" like you do on everything else. At 35 MPH plus you can break the shaft on a terrova and it was a very wet run. Minn Kota says a limited lifetime warranty on the composite shaft and they replaced it free. I now also have a bungee cord that I use to tie down the unit while running down the lake.

Ouch!

Well tried it out today with new batteries! Wind was not terrible but seemed to have much more power after battery replacement! Hopefully that has fixed the issue!

Glad your back on the water.