Electric Trolling Motor stopped working

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Paul (admin) Paul (admin)
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Electric Trolling Motor stopped working

My 32lbs trolling motor died just after leaving Goring lock on the 2016 Thames Raid. I thought it might have overheated so waited for things to cool down. Still no movement. In the end Phillip towed me the remaining mile or two to Beale - thanks Phillip.

Back home I took the prop off and undid the long bolts that hold the motor together. Black oily water dribbled out - oh dear I thought. It wasn't full of water, but somehow a little bit of water got in (corrosion near one of the seals I think) and mixed with the grease.

Taking the armature and magnets off reveals the brushes which were in a sorry state:



The right hand brush had worn away completely, even a bit of the spring is missing, which broke the electrical contact with the armature. So with no current flowing the motor is dead.

Carbon brushes are as cheap as chips on ebay (£2 upwards) but the remaining brush is 9.6mm x 6.1mm, which is a weird size. The 6.1mm is 10 thou under 1/4in and 9.6mm is 2 thou over 3/8in so they might be an imperial size.
But 9mm x 6mm is a common size, the problem is finding some with a long enough lead although I could solder them to the existing braided wire. I'm not sure what the starting length should be, around 12mm seems standard.

Has anybody got any experience of replacing brushes?

thanks
Paul
Say NO to Brexit. Kick it into the long grass
Timmo Timmo
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Re: Electric Trolling Motor stopped working

Have changed numerouse brushes on Henry Hoovers... not the same I know! Not least because I can buy parts specified for them Those brushes start about 4cm long (and wear to nothing in about a year of daily hard use.) They are very cheap as you say.

Seems to me its a case of the longer the better provided they fit.

What's the make, model and serial number of the motor? A search on-line might find the spec for the brushes, maybe even a supplier that will guarantee a fit.

Also suggests even electric trolling motors need a strip down and overhaul every now and then. Don'y forget to source a new seal as well.

Tim.


On 10 Jun 2016, at 09:48, Paul (admin) [via UK HBBR Forum] <[hidden email]> wrote:

My 32lbs trolling motor died just after leaving Goring lock on the 2016 Thames Raid. I thought it might have overheated so waited for things to cool down. Still no movement. In the end Phillip towed me the remaining mile or two to Beale - thanks Phillip.

Back home I took the prop off and undid the long bolts that hold the motor together. Black oily water dribbled out - oh dear I thought. It wasn't full of water, but somehow a little bit of water got in (corrosion near one of the seals I think) and mixed with the grease.

Taking the armature and magnets off reveals the brushes which were in a sorry state:



The right hand brush had worn away completely, even a bit of the spring is missing, which broke the electrical contact with the armature. So with no current flowing the motor is dead.

Carbon brushes are as cheap as chips on ebay (£2 upwards) but the remaining brush is 9.6mm x 6.1mm, which is a weird size. The 6.1mm is 10 thou under 1/4in and 9.6mm is 2 thou over 3/8in so they might be an imperial size.
But 9mm x 6mm is a common size, the problem is finding some with a long enough lead although I could solder them to the existing braided wire. I'm not sure what the starting length should be, around 12mm seems standard.

Has anybody got any experience of replacing brushes?

thanks
Paul
Sail when you can, motor when you can't http://www.millibee.co.uk



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Paul (admin) Paul (admin)
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Re: Electric Trolling Motor stopped working

It's a Rhino R-VX 34 - German distributor of a clone of the Minn Kota.

On further examination the armature was covered in what I can only describe as "magnetic dry mud". Mud ground up with fine metal perhaps.

Even more careful inspection and I noticed a crack in one of the permanent magnets had opened up. The magnet was glued once but now slides out. My guess is that is where the ground up "magnetic mud" came from - there seemed to be very little clearance between armature and magnets and they might have been abrading each other.

There is also angular play in the rear thrust bearing. Not much side play though.

So I either try and epoxy the broken magnets into the case,....which risks all sorts of imbalance in the magnetic field and misalignment........or throw in the towel and declare it as knackered.

It's done at least 3 Thames trips, probably 200 miles+.  But that's 200 miles of silence and zero pollution for the paddlers.

-Paul
Say NO to Brexit. Kick it into the long grass
Timmo Timmo
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Re: Electric Trolling Motor stopped working

Sorry, took a couple of days to get time to have a look.

According to this page


your motor takes brushes part number 9925 724. RRP is apparently £11.50. Regretfully no pictures that I could find that would indicate length and nowhere responds when I Google for 9925 724 compatible brushes.

If Rhino don't make the motor itself there may be separate identifiers there that would enable you to bypass the 'boating premium' and access cheaper spares.

Tim.


On 10 Jun 2016, at 15:37, Paul (admin) [via UK HBBR Forum] <[hidden email]> wrote:

Rhino R-VX 34

Paul (admin) Paul (admin)
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Re: Electric Trolling Motor stopped working

This post was updated on .
Tim,

Thank you for the excellent detective work. £12 is a bit steep compared to £2 or £3 on ebay. But John is right it's not difficult to file down a larger size - but very messy though so wear gloves.

In this image I have highlighted the semi-circular permanent magnets, glued inside the casing. They also hold to the case with a strong magnetic force of course.



I think one of the magnets had detached and moved a few thou to somehow come in contact with the armature. That, or some other mechanism, ground off the detached magnet whose magnetic fillings mixed with dirty water-oil sludge.

How one magnet cracked along the length I don't know, but muggins here managed to break one half leaving 3 pieces that all repel each other.

I think it is game over, unless somebody loves the challenge of repairing a broken motor with broken magnets for free. You know you want to Phil!!

I'll probably replace the old work horse with a Minn Kota C2, simple low power with plenty of spares and diagrams available.

-Paul

Say NO to Brexit. Kick it into the long grass
Timmo Timmo
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Re: Electric Trolling Motor stopped working

You've certainly got a problem there.

Loads of electric outboards on e-bay at all prices. There's a Rhino but looks like a different model so not a spares prospect. 

A nice shiny new one will be fun!

Tim.


On 14 Jun 2016, at 19:06, Paul (admin) [via UK HBBR Forum] <[hidden email]> wrote:

Tim,

Thank you for the excellent detective work. £12 is a bit steep compared to £2 or £3 on ebay. But John is right it's not difficult to file down a larger size - but very messy though so wear gloves.

In this image I have highlighted the semi-circular permanent magnets, glued inside the casing. They also hold to the case with a strong magnetic force of course.



I think in mine one of the magnets had detached and moved a few thou to somehow come in contact with the armature. That, or some other mechanism, ground off the detached magnet whose magnet fillings mixed with dirty water-oil sludge.

How one magnet cracked along the length I don't know, but muggins here managed to break one half leaving 3 pieces that all repel each other.

I think it is game over, unless somebody loves the challenge of repairing a broken motor with broken magnets for free. You know you want to Phil!!

I'll probably replace the old work horse with a Minn Kota C2, simple low power with plenty of spares and diagrams available.

-Paul

Sail when you can, motor when you can't http://www.millibee.co.uk



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inwe inwe
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Re: Electric Trolling Motor stopped working

Sorry to bring you bad tidings but the armature looks recoverable and it is Not the issue with a DC motor. Cut a couple of new bearings from a bar of phosphor bronze and run some emery cloth over the armature and it will be fine. The real problem lies with the commutator. This at the very least will need skimming and truing up and the micas re- cut. It is the comm that the brushes run on NOT the armature. Having kept many a starter motor and generator working over many a year, it is this part that gives the most trouble. Get the rotating bit running true and then get the commutator running true. The brushes need to run over a true surface. New brushes can be made from a set that are too big. File them to fit.
Alternatively scrap it and get a new motor.

Richard
Randonneur Randonneur
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Re: Electric Trolling Motor stopped working


On 15 Jun 2016 22:41, "inwe [via UK HBBR Forum]" <[hidden email]> wrote:
>
>  The real problem lies with the commutator.
it is this part that gives the most trouble.
> Alternatively scrap it and get a new motor.

Which begs the question, why on earth are we using inefficient brushed motors in this application?  A brushless setup with ESC should be a doddle.
It is 2016 not 1976....

I'd bite the bullet and build my own. 

PP

philoxuk philoxuk
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Re: Electric Trolling Motor stopped working

In reply to this post by inwe
No thanks! I agree with Richard.

And Pete, for that matter......

Cheers,

Phil.
Paul (admin) Paul (admin)
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Re: Electric Trolling Motor stopped working

In reply to this post by Randonneur
I tend to agree with Pete, although I don't have the time or interest to have a go.

Yes the commutator is knackered............maybe she needs to be buried in Davy Jone's locker.

-Paul

Say NO to Brexit. Kick it into the long grass
inwe inwe
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Re: Electric Trolling Motor stopped working

The comm looks recoverable after truing up on a lathe. Clean it all up and re-lacquer the windings. Not too long a job.

Richard
Paul (admin) Paul (admin)
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Re: Electric Trolling Motor stopped working

Richard

Agreed. This is a great excuse for some "retail therapy" buying a 7x12 lathe

Paul
Say NO to Brexit. Kick it into the long grass
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