MinnKota Fortrex lost power

[dougfire]

I have a 36 volt Fortrex on 2013 520 C. 2 days ago while moving from one brush pile to another on 100 setting it lost about 70% of power in a fraction of a second. still used it for 3 more hours but it felt like it was 20%. got home checked all connections at batteries, looked good. charged as usual, all batteries charged in the morning. Batteries are DEKA, voltage on batteries was 13.24 , 13.08 ,13.20. Anyone have an idea what else I need to check? It was like it had the old 12 - 24 volt switch on it. thanks in advance

[Bradrodfish]

You have a battery that is bad internal. Bad cell. This happens when the battery is put under load. Get them load tested.

[5keepers2]

Did you check and make sure none of breakers are tripped or bad on trolling batteries? Test voltage passed breakers or outlet side of each breaker?

[Tremp Mike]

I had a similar issue with mine last week. Power would drop intermittantly. Good batteries and connections. Pulled the long bolts out of the motor housing and they were black and stunk like the armature got burnt. Took motor 2.5 hrs to MK dealer hoping for quick turnaround as I called them several days in advance. They said water intrusion fried the armature and softened the balancing putty and recommended a new lower unit assembly for $465 installed. Since the parts were not in stock at dealer and I still had roughly 75% power and the fishing is still good, I thought I would have them fix it during the off season. Brought it home, re installed it and when I tried to run it, nothing. No power, nothing. I was a little hot because they didnt test it after they put it back together and I would have left it there if it didn't work. Here's the good news. Called Minn Kota on Thursday AM and had a new lower unit and composite shaft (lifetime warranty) the next day. I live in WI and UPS ground was one day delivery. I had it installed in about 2.5 hours taking my time. It pays to unassemble slowly and take pictures in the process. Might be good idea to replace/lube both bearings at the same tome. Loktite red is what MK recommended to use between the shaft and motor threads. From 1-10 it was about a 7 in terms of difficulty. It was faster for me to do it myself than to drive back to Mpls (twice). If you go that route and need some advice feel free to PM me. I'm not saying your issue is the motor as there are a couple boards as well that go bad. Sorry for so long. Bottom line, pull one of the long bolts out and see if it's wet or burnt

[dougfire]

Bradrodfish, i saw your reply. went to Tractor Supply today and bought the $33 model. I tested all 4 batteries, the last one showed 13+ volts until I tested it. Went from 13V down to 6V. Saved me alot of frustration. Thanks for your suggestion

[John Jones JTM]

I'm guessing it was the 13.08 battery that tested bad. Yours is typically the story on how a trolling motor acts when a battery goes bad.
To Tremp Mike: I'm glad you got it resolved through MinnKota. I hate to say it, but the ASC was most probably telling you a story. I've seen hundreds of trolling motors with water in them, and I've yet to see the water intrusion burn an armature. It will turn black for the customer to see, and the inside will be a mess because the water mixes with the graphite brush dust and makes what looks like an oil sludge, but that all will clean out. The armature can be put on a lathe and spun to throw the water out, then finish drying with a heat gun. The brushes may need replacing due to water having sand in it and will cause the brush to wear prematurely. I have brought many a unit with water intrusion back. However, like I started off, I'm glad that MinnKota took care of you.
John