Minn Kota - Running with low thrust?

[Bestred1]

I have a Minn Kota Riptide (saltwater series) 70-lb thrust, 24-volt, manual control, bow mount, 4-years old. Its running with about half the thrust it had when new.

I replaced both batteries this past spring. Shortly after replacing the batteries, the switch went bad (5-fwd/3-rev) so I replaced it. At the same time I found some corrosion at the connector plug. I restriped the wire and fixed the plug. I also looked at the female plug on the boat side and its connections are fine. Just to be certain, I disconnected the wires and put it back together.

I'm still having the same problem of running with about half thrust. It's also tripping the breaker when running on the top speed setting after just a few minutes. Someone suggested that I check the brushes so I did that today. They look fine and so does everything inside, no water intrusion. I put it back together and ran it for a few minutes. The only thing noticeable was that the shaft got real hot. Any ideas? Maybe a new armature is needed?

 

[Splat]

Re: Minn Kota - Running with low thrust?

Assuming there was no fishing line wrapped around the main shaft when you disassembled?

It's possible the brushes are worn, it's even possible that the armature is loosing some of it's magic. When you had the motor opened up, was there any electrical smell inside, any sign of burnt contact between the brushes and the contacts on the armature?


When the motor is out of the water and you select through the 5 speeds, can you hear or see a noticeable change in the RPM? or do you have something funny like speeds one, two and 3,4,5 are all the same? You could have a burnt gizmo (sorry it's late and I can't think of what the damn thing is called, rectifier, resistor, carbon pile? my fellow electrical guys know where i'm going, some one will be by shortly to finish that thought.)

Bill

 

[Bestred1]

Re: Minn Kota - Running with low thrust?

Thanks for the reply Bill.

There was some line wrapped around the shaft but it wasn't much. At least not enough in my mind to knock the thrust down as much as I've been experiencing.

The motor looked great inside. Nothing looked or smelled burnt or shorted. Contacts looked good. A little wear on the brushes but about what you'd expect. Not enough to consider replacing.

It changes RPM through all 5-fwd speeds and the 3-rev speeds. The front seal has some dry-rot cracks in the rubber so I'm going to order one and replace it before it starts leaking.

I'm going to put it back in the water just to ensure it wasn't the line. If it's still the same, I'll be headed back to the store with my batteries to have them load tested unless someone has other suggestions.

 

[Splat]

Re: Minn Kota - Running with low thrust?

Hmmmm.... Yea I don't really have a good answer.

Typically what we covered is the most common causes of power loss. Especially the fishing line.

Its possible your magnetic field in the motor is getting weak but theres no real way to check/fix that. Load testing the batteries may tell you somethin, but I would expect a bad battery to quickly die while being used.

Let us know how the batts check out.

Bill

 

[Bestred1]

Re: Minn Kota - Running with low thrust?

I put my meter at the battery cable to see how much current it was drawing. It's only drawing 3.0 amps at full speed. No load and out of the water but this seems low doesn't it?

I haven't been able to find anything on the web that would tell me what the normal draw should be.

 

[Splat]

Re: Minn Kota - Running with low thrust?

My 55 minnkota Terrova, draws 8 amps, out of water no load, full speed.

Mine uses a digitizer tho to control speed.

3 may not be unusual, But I don't have a reference point.

Bill

 

[john from md]

Re: Minn Kota - Running with low thrust?

Three amps for your motor seems too low to me. I know this seems basic but have you done a load test on your batteries? I understand they are new but I have had new ones fail early one.

If one is down, it can still read 12v but have no amperage behind it. Essentially it would be like operating at 1/2 power.

John

 

[Bestred1]

Re: Minn Kota - Running with low thrust?

I'll be headed back to the store this weekend with my batteries to have them load tested. I'll post the results.

 

[Silvertip]

Re: Minn Kota - Running with low thrust?

In the water it will draw about 45 - 48 amps at full speed. If the shaft is getting hot, there is high resistance somewhere in the system. Loose or corroded connections are the usual suspects. The fact that the breaker is popping at high speed also says it has degraded and no longer capable of handling the current at high speed. Each time a circuit breaker trips it loses a small bit of its current handling. Replace it and double check all connections from batteries to the actual motor (down the shaft).

 

[Bestred1]

Re: Minn Kota - Running with low thrust?

My batteries both passed load test.

This is a bit ridiculous for a mechanical guy like myself. I'm beginning to remember why I hated the electrical stuff in the Physics courses I took in college.

Tomorrow, I'm headed out to locate a new breaker at a local outboard parts store.

More to follow.........................

 

[Bestred1]

Re: Minn Kota - Running with low thrust?

Well........................My frustration continues!

New breaker, same old results.

3-amp draw and hot motor shaft. My meter has a thermocouple so I put it on the shaft after a few minutes of running. It nearly hit 200 degrees F! No wonder the front seal looked bad with this kind of heat.

I'm still thinking a bad armature which will cost me about $60 to replace. I haven't spent much to this point and am close to just taking it to a trolling motor shop that's been recommended by a good source. Problem is, these folks keep banker's hours of 9-4 M-F. Must be nice huh? I just hate paying somebody since I'm the best mechanic that I know. I'm just not a good electrician.

Any other suggestions or similar experiences out there?

 

[Bestred1]

Re: Minn Kota - Running with low thrust?

In between showers today I dropped it in for a quick run on the trolling motor.

It's drawing between 53 & 55 amps at top speed. 15 to 20 at speed-1. A little more at 2 thru 4. Jumps from about 30 to 55 when going from 4 to 5. It didn't trip my new 50-amp breaker but I can see now why it was previously. After pulling the motor out of the water, the casing is warm to the touch after just a few minutes.

Any thoughts?