Author Topic: No charge!  (Read 1797 times)

Offline roadrocket

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No charge!
« on: 16.07. 2014 19:24 »
A very common heading I'm sure, but everyone's a bit different. I have no charge despite many efforts: I have checked that dynamo works as a motor, which it does quite convincingly, and the same way around, anti clockwise, as when running. The wiring inside the dynamo is correct, with Field connected to earth via one brush, and the other brush directly to Dynamo on the end cover. Ammeter shows discharge when lights are on. I have polarised the dynamo. I have checked belt drive to dynamo. Voltage regulator is spanking new. What can possibly be wrong? Next step is Alton generator!

Otto in Denmark
Otto in Denmark

Offline beezermacc

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Re: No charge!
« Reply #1 on: 16.07. 2014 20:12 »
The fact that the dynamo motors is not an absolute test. In an ideal world you need a 'growler' to test the armature but checking the output on the bike with a 12v bulb or voltmeter should be good enough. Are you doing the usual test, i.e. disconnect the D and F wires, bridge the terminals, connect the bridge back to the dynamo body via bulb or multimeter, run the bike slightly over tickover and check output?
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Offline roadrocket

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Re: No charge!
« Reply #2 on: 16.07. 2014 20:54 »
Thanks, will try that.
Otto in Denmark

Offline trevinoz

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Re: No charge!
« Reply #3 on: 16.07. 2014 22:32 »
As Andrew said, motoring is not the ideal test, unless you have a variable voltage available. Usually, if a generator will motor at 3-4V, it is OK.
I have a growler but never use it, I prefer to "voltage drop" the armatures.
In fact, there are people with growlers who don't have a clue how to use them properly and only test for short circuits, completely disregarding open circuits, which is the most common fault.
Then there are earth faults, uncommon, but again, disregarded.

Trev.

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Re: No charge!
« Reply #4 on: 16.07. 2014 23:53 »
My dynamo passed all tests but would not self generate enough voltage in the field coil eg kIck off charging after a few hundred miles unless I cleaned the armature. I got tired of doing this obviously...... *problem* *pull hair out*

New brushes solved the problem  *wink2*. Seems the old ones had gone soft or were the wrong material.

A test for this problem is to apply power to the field with the engine running and see if it starts  generating and then keeps generaring when you remove the power to the field coil.

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Offline roadrocket

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Re: No charge!
« Reply #5 on: 17.07. 2014 10:36 »
Read a good article about testing the dynamo; it looks like my field coil is shot. The dynamo yields 0,35 V, and the resistance between field and earth is 0,05 ohm. Have ordered new field coil. Thanks chaps!
Otto in Denmark

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Re: No charge!
« Reply #6 on: 17.07. 2014 18:30 »
apply power to the field with the engine running and see if it starts  generating and then keeps generating when you remove the power to the field coil.

Yes, always try that one, with the engine running at a fast idle.

Offline roadrocket

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Re: No charge!
« Reply #7 on: 23.07. 2014 14:57 »
So I changed the field coil... Everything nicely assembled, polarised and with big hopes I fired up. No charge! I have changed armature, control unit and field coil. No charge. I will now buy an Alton generator, and never need to worry again.
Otto in Denmark

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Re: No charge!
« Reply #8 on: 23.07. 2014 18:07 »
Try reversing the brush connections, to reverse the dynamo's direction.

Did you try briefly putting battery live to to dynamo F, with engine at fast idle?

My Alton failed in service. So did the supplied regulator.


Offline roadrocket

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Re: No charge!
« Reply #9 on: 23.07. 2014 20:24 »
Hi Triton; do I do that with both D and F connected to the regulator? The Dynamo turns the right way around (anti clockwise) when motoring, so I take it the brushes are OK? I have now cleaned the cummutator for good measure, but have not fired up yet, as the neighbours would probably not like it at this hour.
Otto in Denmark

Online morris

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Re: No charge!
« Reply #10 on: 23.07. 2014 20:55 »
Try reversing the brush connections, to reverse the dynamo's direction.

Did you try briefly putting battery live to to dynamo F, with engine at fast idle?

My Alton failed in service. So did the supplied regulator.
Also had to reverse the brush connections on my dynamo to get it going after a rebuild so well worth a try. Seemed illogical to me at the time because I was 100% sure I reconnected them as they were before but had 0 output until I (accidently I admit) connected them the other way round...
You can easily test a dynamo outside the bike. I use a 4" length of rubber tube, push it on the shaft, and use an old drill bit in a drill to drive the other end. Connecting D & F together should give at least 10-14V at drill speed.
About the Altons, a bloke from wich I buy spares and who used to sell Altons told me he gave up on them because of to much returned units and an almost none existing manufacturers support.
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Re: No charge!
« Reply #11 on: 23.07. 2014 21:34 »
Hi Triton; do I do that with both D and F connected to the regulator?
Yes. With engine running fast enough that it should be charging and everything connected normally, get 6 or 12V live onto the F, with some sort of jump lead from the battery live. Just for a second or so.  It sometimes wakes the dynamo up.


 
Quote
The Dynamo turns the right way around (anti clockwise) when motoring, so I take it the brushes are OK?

I don't actually know if motoring direction is the same as charging direction, but reversing the brush pigtails has worked for me, with a new (to me) dynamo, in the past.


Offline trevinoz

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Re: No charge!
« Reply #12 on: 23.07. 2014 22:25 »
Motoring direction is the same as generating.

Trev.

Offline roadrocket

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Re: No charge!
« Reply #13 on: 24.07. 2014 15:59 »
I have now measured the resistance between the segments on the commutator, and I have nil resistance between any of them. I guess thats bad? The armature has been rubbing on the field coil retainer, but the dynamo has worked since that up to a point. So new armature?
Otto in Denmark

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Re: No charge!
« Reply #14 on: 24.07. 2014 17:47 »
You may have fitted the field pole shoe wrongly. It's something of a specialised job.

Testing an armature needs special gear too.