Trolling Motor Keeps Blowing Fuse

capeters · Jun 1, 2012

Let me begin by saying I am a total newbie to boat ownership and electrical work. So, if you have any advice you could give me, it will be greatly appreciated (but please dumb it down for me)!

The problem:
I took my fish/ski combo out for a day of fishing. I had been using the trolling motor for 3 or 4 hours with no problems. All of a sudden, the trolling motor stops working. I knew enough, just from reading this forum, that one of the first things i should do is check the fuse. The fuse was blown. I took the trolling motor out of the water and up onto the deck, and then I replaced the fuse. I ran the trolling motor, while it was still on the deck of the boat, out of the water, and it ran perfectly. I dropped the trolling motor back into the water, attempted to use it, but it stopped working again. I checked the fuse........again it was blown.

What could be causing this? Like I said, I am a newbie to boats and things electrical, so take it easy on me please!

thanks for your help.

Craig

Scott Danforth · Jun 1, 2012

Re: Trolling Motor Keeps Blowing Fuse

the motor could have issues.

does the motor turn easy by hand? or does it have a great bit of resistance?

My father's trolling motor would do that a few years ago. it would run great in air (no load), however as soon as it hit the water it would blow the fuse. took it apart and everything was corroded. turns out the trolling motor got submerged when he left it in the boat with the plug it in. he thought the whole unit was sealed. not much to do but replace the whole thing.

not saying this is your problem, however there is potential that your motor could have had a leaky seal, etc.

capeters · Jun 1, 2012

Re: Trolling Motor Keeps Blowing Fuse

Thanks for the reply. Yes, it does turn easily by hand. It has worked well the three times I have used it this year....It just seemed to happen out of nowhere. It is 13 years old, so maybe some of the seals have given way due to old age?

mistertwister87 · Jun 1, 2012

Re: Trolling Motor Keeps Blowing Fuse

What type of trolling motor and what lb thrust? Also how large is your fuse? You need to make sure your fuse is just above the max amps your TM will pull on full power. For example my Trolling motor pulls a max of 56 amps at when it is run on full power, therefore I have a 60 amp fuse.

capeters · Jun 3, 2012

Re: Trolling Motor Keeps Blowing Fuse

The trolling motor is a 13 year old Motorguide, 46 lb thrust. The fuse is a 40 amp fuse. I don't have the paperwork on the motor, but I think that 40 amp should be plenty......but maybe not. After some suggestions from others, I removed the prop. I found a ton of line and gunk on the prop shaft. That may have had something to do with the problem, but I guess i won't know until I can get it into the water.

NYBo · Jun 3, 2012

Re: Trolling Motor Keeps Blowing Fuse

I would think a 50 amp fuse would be more appropriate. Older 12V trolling motors use about 1 amp per pound of thrust at full speed. A manual reset circuit breaker might be even better.

capeters · Jun 4, 2012

Re: Trolling Motor Keeps Blowing Fuse

NYBo said:
I would think a 50 amp fuse would be more appropriate. Older 12V trolling motors use about 1 amp per pound of thrust at full speed. A manual reset circuit breaker might be even better.

Do you hook up a circuit breaker the same way the fuse is wired?

Scott Danforth · Jun 4, 2012

Re: Trolling Motor Keeps Blowing Fuse

yes, the only difference is the circuit breaker has the terminals marked "batt" and "Aux" where the fuse doesnt.

Silvertip · Jun 4, 2012

Re: Trolling Motor Keeps Blowing Fuse

Scott Danforth said:
yes, the only difference is the circuit breaker has the terminals marked "batt" and "Aux" where the fuse doesnt.

Or the terminals may not be marked in any way. Standard breakers can be wired with either terminal on the battery and either terminal on the load.

capeters · Jun 11, 2012

Re: Trolling Motor Keeps Blowing Fuse

Thanks for your help. I think I will give the circuit breaker a try......50 amp. I am not sure if this has anything to do with the blown fuse, but a couple days ago I removed the prop, and I found a ton of fishing line and other debris wrapped around the bottom half of the prop shaft. Could this cause the trolling motor to draw more amps and cause the fuse to blow?

NYBo · Jun 11, 2012

Re: Trolling Motor Keeps Blowing Fuse

Just be sure to buy a manual reset breaker. With an auto-reset breaker, the motor could start back up while you're trying to figure out why the breaker popped and you have your hand in the path of the prop.

capeters · Jun 12, 2012

Re: Trolling Motor Keeps Blowing Fuse

Thanks...Will do. I just purchased the breaker yesterday, and I will be installing it today.

NJVic · Jun 9, 2017

CAPETERS, I know this is old but...there should be a sticker on the motor that shows model/serial number. It'll also show a KW:xxxxxx. Those are the kilowatts the motor is rated at.

FYI...If it is 00.28kw, then:

multiply by 1000 (because you're dealing with kilo).

You get 280 watts.

Now, divide that by voltage:

280/12 = 23.3a

Don't just blindly throw a 50a in there. Use a 30a which is more appropriate.

If there is a problem, you don't want the circuit to handle 2x what it should be handling before it blows.

Bad advice on the 50a suggestion.

Silvertip · Jun 9, 2017

Yes -- fish line wrapped tightly around the motor shaft can cause drag which amounts to increased load on the motor and increased current consumption and hence the blown fuse. You should not use a fuse with a troller anyway. The advice you were given regarding a circuit breaker is "good advice". 50 amp rating is essential for that motor. At the highest speed setting, inrush current can spike very high and fuses simply can't handle that unless it is a "slow-blow" type.

Silvertip · Jun 9, 2017

NJVic said:
CAPETERS, I know this is old but...there should be a sticker on the motor that shows model/serial number. It'll also show a KW:xxxxxx. Those are the kilowatts the motor is rated at.

FYI...If it is 00.28kw, then:

multiply by 1000 (because you're dealing with kilo).

You get 280 watts.

Now, divide that by voltage:

280/12 = 23.3a

Don't just blindly throw a 50a in there. Use a 30a which is more appropriate.

If there is a problem, you don't want the circuit to handle 2x what it should be handling before it blows.

Bad advice on the 50a suggestion.

You just gave bad advice. I've never seen a trolling motor where the tag indicates KW of that motor but of course, that does not mean it doesn't exist. In fact I've never seen a trolling motor that has a current rating on its ID tag. You find the recommended fuse/breaker size in the owners manual. 2) You find the maximum current draw from the specifications for the motor in the manufacturers literature. Minnkota circuit protection recommendations are: 50A for 30, 40, and 45# motors and 60A for 50 & 55# motors. Their specs for a 30# motor show 30A max draw, 42 amps for 40 & 45# motors, and 50 amps for 50 - 55# motors. So you see, a 30 amp fuse would be toast in a heartbeat regardless what motor he has.

fishrdan · Jun 9, 2017

5 YO thread, please close mods....

GA_Boater · Jun 9, 2017

NJVic said:
CAPETERS, I know this is old but...there should be a sticker on the motor that shows model/serial number. It'll also show a KW:xxxxxx. Those are the kilowatts the motor is rated at.

FYI...If it is 00.28kw, then:

multiply by 1000 (because you're dealing with kilo).

You get 280 watts.

Now, divide that by voltage:

280/12 = 23.3a

Don't just blindly throw a 50a in there. Use a 30a which is more appropriate.

If there is a problem, you don't want the circuit to handle 2x what it should be handling before it blows.

Bad advice on the 50a suggestion.

You can figure out the thread is old, but not that the OP hasn't been around in 5 years. Brilliant!

Closed.

Trolling Motor Keeps Blowing Fuse

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