I have a 80 lb thrust Minn Kota Maxxum Pro trolling motor on my boat. I have been having problems with it shutting down while I'm on the water. Lasted about an hour last week before it shut off. The batteries were tested by the dealer and they check out fine. I had the dealer replace the plug, receptacle and connections and they said it works fine. Well, I get on the water Sunday and it wont even work for me. So, the dealer looks at it this morning and says it works! This is after a night of charging the batteries. The dealer was starting to tee me off telling me that there is an on/off switch on the motor etc.
Can batteries test good after a night of charging and put out some power and then just shut down????

Since you had the connections checked out and there were no open circuits its your battery that is more than likely bad. It has an open cell in it. Just had the same problem with a battery of mine. Charged it up the night before. Stuck the volt/ohm meter to it and it read 12.6V. Stuck a load on it and nothing worked. Got a new battery, problem solved.

Marc

Could also be an undersized "Thermal Cut-off" used to protect the wiring between the batteries and motor. As current passes through the thermal cut-off it will heat and shut off but reset after it sits. If you went to a larger motor it may not be the correct amperage rating now. I prefer a properly sized marine grade circuit breaker.

Hey guys, thanks for your responses. I know the guy only checked the batteries with a voltmeter, so I'm hoping its a bad cell.The trolling motor runs on a separate circuit from all the other electronics and has a fuse built in to the circuit (Ranger Boat), but they have never 'popped'.
John 175, not sure if I have a thermal cut-off. Where would it be located. Thanks.

Go somewhere where they sell golf car batteries. Have them put a 'load test' on them. That will at least let you know if it is the batteries or not.

SE Kansas grass grower

Look under the bottom of the trolling motor pedal where all the switches are for the trolling motor. Also if you have a Hi speed by pass and have used it at all for a extended peroid of time it will weaken the thermal breaker for the motor.

Do what ring fry said.

If your batteries are good, they should read 13.2 Volts when they are fully charged. I've owned at least 20 trolling motor batteries and they all read 13.2V when they were in good condition and charged.

However, I don't think that is your problem. If the motor didn't work at all when you tried it, I would start looking for a bad connection. I have found them in the pedal, in the boat, at the batteries and behind the bow plug. Start taking things apart with the trolling motor turned on and the prop removed. When you get to the bad connection, the motor will start running. You may be surprised how easy it can be to find this way.

Artie

Artie, I think both batteries registered at 11 volts, when he tested them, which he thought was ok because he tested a battery on the showroom floor and it tested the same.
Is the thermal cut-off actually located on the bottom of the pedal? My pedal is attached to the deck of the boat. I'm wondering, if it is accessible or if I will have to remove it first.

Sounds like you have a bad armeture.

Next time it stop working, turn the prop a little and see if you indeed have a dead spot on the armeture.

MK was having a problem with this.

If not that, then it might be your circuit board. Your TM should under warranty....

State of Charge
Specific Gravit Voltage
12V 6V
100% 1.265 12.7 6.3
*75% 1.225 12.4 6.2
50% 1.190 12.2 6.1
25% 1.155 12.0 6.0
Discharged 1.120 11.9 6.0

Just wanted to give y'all an update, in case you have similar problems. It turned out to be a bad circuit board. Also, the newer motors dont have a thermal cut-off switch, so that wasn't the problem. I had the batteries load-tested and they were fine. That eliminated them as the source. When the motor died on the water, I attached a voltmeter to the receptacle and got 24volts there, so the wiring and receptacle were working. I basically figured it had to be something in the motor, since I had just replaced the plug. As mentioned earlier, it was the circuit board.
Thanks for all the input and suggestions!

My dad had bought a 70lb thrust minn kota last year around this time. The first couple times we took it on the water it worked fine. After that we'd be slowly fishin an area and it would automatically turn itself on high and it just about threw me out of the boat. It would also randomly turn off when we were using it. We continued to have these problems with it and eventually took it back to Academy.

I have had a problem with my 46 minnkota also. it is not the same problem. it is a transom mount. the model is the 46lb vector transom mount. it has 5 foward speeds and 3 reverse speeds. when i want to go sayin 2nd speed foward it jumps the ggears and goes to 5th speed then jumps back down.
I do not mean to jump in to your post. but if anyone could help it woould be appricated.
Thanks YCat

sorry guys for some messed up spots in the above post.