That's what I was eluding to with my post above. The 4 or 6 gauge wire running from the batteries to the TM have to go through the plug and its 14-18gauge connectors inside. Some, even worse, have even smaller jumpers inside of them. The plugs are KILLERS. Lol.

The worst I have witnessed, and repaired, was an older Edge 55 12 volt. Nothing pulls that kinda current. The 24 and 36 volt motors are far less current hungry. The Edge almost melted the plug into a state of deformation that it would barely even plug into the receptacle.

No, only when it's in water does it do it. And for some reason, when I test it in the trash can, I can't duplicate it but can't really run it on high speeds very long to simulate being on the lake.

If there is a breaker of some sort, it's hidden...I can see battery cable going straight from the battery all the way into the hull and out the bow.

That's exactly what I thought and told them at the shop..but was told that it did not fail under test. I'm thinking on replacing it on my own

In the water bucket, there is no boat slowing down the prop rotations grabbing water flow so electrical current flows in the motor windings and the temperatures are not quite as high as later seen out on the lake.

You seem to be describing a temp sensitive make/break bad wire/connection inside your TM; possibly in the motor.Under max current it heats and opens. When it does open, current ceases, motor stops and then it cools and remakes.

Planning on contacting MK and seeing what they suggest or will do at this point. Even at 20', I rarely ever need speeds 80-100 on an aluminum boat, but when I do need it, I NEED it....and just don't think after 3months, I should be having an issue that a shop can't figure out.

And not being able to duplicate the problem in my garage, but immediately when I'm at the lake, screams to me that the drag and resistance, like Lou mentioned, is playing a part in a motor failure. But getting MK to buy into it is another thing.

You really should have some type of circuit breaker in line. If for some reason there is a short you could have a fire or cause the batteries to explode. I know you are chasing gremlins but if I were you I would have some type of breaker installed. It sounds like when the load is high there is something heating up in the motor causing it to cut out.

Breaker is weak

you can't duplicate the problem in your garage because the trolling motor isn't under a load. Do yourself a favor and go by a $10 manual reset in line circuit breaker. Your gonna need a 50 amp. You really also need 6 gauge wire running to the trolling motor. Now if the breaker doesn't fix it replace the plugs at the bow. I actually remove the plugs first thing and use 100amp lugs. But I like to run my trolling motor hard in the pads and have melted a couple plugs doing so.

If your other TM was messing up also, it is in the boat somewhere. Find the breaker.

I have the opposite problem, cutting out at low speeds. I was told by a Minnkota service guy that it's a bad armature.

I don't have an answer for you, but I hate [censored] like this. If worse comes to worse take it to the lake fork trolling motor guy, hes the best I've ever worked with

Can you snap a couple pics of your setup? I plan on re-wiring the whole damn circuit and I like your "overkill" thinking.

All the above:

I've had this same issue and it was a faulty breaker. Something is cutting power when it gets too "hot" to prevent the motor from burning out. Kind of like when and oil pump goes out on an OB and the computer shuts the engine down to prevent blowing the head. Not sure if TM has such a device built into them or not. Electrical issues are a pain, might try taking it out and running it with a meter on the wiring at the back, really just a process of elimination. Think of it like you would trying to find that short in your trailer lights:)

Check your cable connections or change out your board.