Reduction In Trolling Motor Thrust

[Goose52]

I'm on the 6th season using a Minn Kota Traxxis 45lb trolling motor on my canoe.  The first couple years, the motor produced all the thrust I could use, with the boat reaching hull-speed before the available motor RPM maxed out.  I had plenty of thrust to handle significant wind conditions on the lake as well. As time has gone by, however, I'm noticing that available thrust is diminishing.  I started this season with a fresh TM battery and thrust is still down significantly from when new.  This thrust reduction is confirmed  by a reduction in top speed as indicated by the GPS on my sonar, as well as a noticeable reduction in the ability to handle headwinds.

 

Thinking it might help, I installed new motor brushes and compression springs and that made no difference. In fact, the old brushes were only about 1/3 worn.

 

Question:  Has anyone else noticed a similar reduction in thrust on their TMs and, if so, had any remedies that worked?  Or, do these machines just "wear-out" and need periodic replacement?

 

Yesterday, I got caught in a pop-up thunderstorm and had to make a run for the launch point, bucking headwinds. The 'ole war canoe just about started going backwards in the heavy gusts.  I need to do something about this issue pronto. I'm inclined to just get a new TM, perhaps moving up to a 55lb Traxxis.

 

Thoughts?

[Dogmatic]

My vote, power that beast up! Go with a new 55lb. motor, "War Canoe" dserves it. As far as motor wearing out, makes sense, but I don't know either way. My first thought would be prop, but I know jack about this kinda stuff.

[Choporoz]

 

Question:  Has anyone else noticed a similar reduction in thrust on their TMs and, if so, had any remedies that worked?  Or, do these machines just "wear-out" and need periodic replacement?

The remedy that usually works best for me is to clean out the fishing line that I got wrapped around the prop shaft.  Beyond that, I have routine speed/controller problems, but no thrust reduction issues.

[WIGuide]

6 years and it's already dropping power? I know I wouldn't be looking to buy another one of the same thing that's failing so soon. 

[Way2slow]

Well, you have already done what I would have suggested and that's change brushes and clean the commentator.

That has always been the problem with mine when they loose thrust and speed.  It's not uncommon for one of the brushes to not make good contact and causing it to slow down.

 

From there, I would have to think the next step would be to take the armature out and to a motor shop to have it tested and do some continuity checks on wires. 

 

Electric motors don't get weak and loose power just  from age without something going bad or bad connections.

[Goose52]

The remedy that usually works best for me is to clean out the fishing line that I got wrapped around the prop shaft.  Beyond that, I have routine speed/controller problems, but no thrust reduction issues.

 

I check for line wrapped on the prop shaft frequently - no issues there.

 

Well, you have already done what I would have suggested and that's change brushes and clean the commentator.

That has always been the problem with mine when they loose thrust and speed.  It's not uncommon for one of the brushes to not make good contact and causing it to slow down.

 

From there, I would have to think the next step would be to take the armature out and to a motor shop to have it tested and do some continuity checks on wires. 

 

Electric motors don't get weak and loose power just  from age without something going bad or bad connections.

 

All connections are good - solid and no corrosion.  The battery is in an MK battery box and those connections are good. The TM extension cables are 6ga and solid. The TM connects to the extension cables with an Anderson SB50 quick disconnect and that's solid.

 

Short of finding a motor shop in my little town (or having to drive to the "big city"), I think the next step is to take the battery back to Walmart and have it checked out. It's date coded 5/15 so it's a fairly new battery...

 

Thanks for the replies.

[Goose52]

Another thought - has anyone had any issues with the digital maximizer controller board or the potentiometer that resulted in limiting available thrust?

[Way2slow]

All you have to go by for the battery is the date code but they sometimes lie. That's just the date the distribution center put it in that store. Not saying Walmart does this but I have worked with battery distributers enough to know some are not very ethical when it comes to date codes. They typically give a battery a 12 month shelf life, and it should have a maintenance charge a couple of times during that 12 months. The retail folks don't typically do that maintenance charge so what happens a lot of times, after a battery has been sitting several months, they get picked up, the distribution center may or may not do a maintenance charge on it, and then place it in another location, with a new date sticker on it for they date they put in the other location.

Another tidbit of info. batteries are somewhat under rated to allow for some degradation while sitting on the shelf. A new, fresh from the factory, fully charged, battery will usually show as much a 20% more CCA capacity when checked with a Megtronics Tester, and will still show it as a good battery when it will only show 10% less than the rated capacity. So, you can have a half used up battery that you just bought off the shelf and they will still say it's a good battery. When I buy a battery, I take my Metronics with me so I know what I'm getting.

As for the digital controller, I have had several fail. I should be easy to check by popping the top off, put a voltmeter on the motor leads (the leads from the controller down the shaft to the motor) and start turning it up. When it gets to max, it should be sending the motor the same voltage as the battery is sending to it.

I will be a pulse width modulated signal so ideally you would want an O-scope to look at it, but I would think there would be some voltage drop also, and you should be able to se that on a good digital multimeter.

[Goose52]

Way2slow - thanks for the detailed response.  Next rainy day when I have some time I'll check the voltage going down to the motor. No oscilloscope available - haven't used one in almost 40 years but I do have a digital multimeter.