Misc: Charging Systems Dynamo Testing

[LoneStar]

Hello all,

I'm working on a Rapide project, and the activity of the moment is to assemble a working dynamo. I have an original Miller D6, and have just replaced the armature and field coil with new units. I have a Podtronics negative-earth regulator, so have wired the dynamo per the Podtronics instructions (attached). The brushes are in good condition, and show low resistance between carbon and ring terminal.

After installing the new components, I flashed the field coil with +6V to the D terminal, -6V to the case. I then followed the Podtronics instructions for motoring the dyno, and it did spin nicely.

This was all very encouraging, so I tested its output. With no regulator, the F terminal was temporarily connected to earth to feed full voltage into the field coil for testing. The dynamo was spun and voltage measured. Here's where the problem comes in - it generates only minimal voltage. Even at 1000 rpm, output rises to only 0.4 V.

What could be wrong? As the Vincent has a 20% reduction in the dynamo drive, 1000 rpm at the dynamo equates to an engine speed of 1250 rpm. I would expect a properly-functioning dynamo to be putting out considerably more than 0.4 V at this speed, but perhaps not - anyone know the proper metrics?

Thanks!

 

[Robert Watson]

Off the top of my head you cannot wire a Miller the same as a Lucas, so that may be where you have an issue. Others will know better than I, although late in life electrickery makes sense in some areas I have not delved into the vagaries of Messers Miller and Lucas.

 

[Bill Thomas]

I am rubbish with electrics ,
But I remembered this from my early Car repair days, Flash to F !!!!.
Hope this helps.

 

[roy the mechanic]

The clue is in the introduction, only for use with LUCAS dynamo.

 

[greg brillus]

Its only a mater of hooking up one side of the field and the left brush to earth, then the other brush goes to the "d" terminal and the other field wire to the "F" terminal.........not hard........If the gen motors over the wrong way then swap the 2 field wires over........easy as. I've been running my original Miller dynamo on my bike since I got it in 2007, using a modern regulator, never had any trouble with it putting out 12 volts.

 

[robin]

connect the 'D' and 'F' terminals together , then flash this junction to the positive terminal of the battery and battery negative terminal to the dynamo body (earth) The dynamo should rotate clockwise looking at it from the drive end . If it rotates anti clockwise swap the field connections over and then repeat.

 

[LoneStar]

No problem with the polarity, and the dynamo does motor in the correct direction when connected to a battery and the field coil jumped. The problem is that it puts out very little voltage at 1000 rpm.

On Lucas vs. Miller - not relevant at this stage, as I'm testing without the regulator. (Although the wiring could be an issue, I'm not clear how.) But I understood that many people have used Podtronics regulators with Miller dynamos, and that Lucas and Miller were pretty much the same in terms of design (once the cutout is removed from the Miller). If not, what are the relevant differences?

 

[Robert Watson]

All I know that when my electrickery guy did a Miller for me he asked if I wanted to wire it as per Lucas which it needed for the podtronics reg.

 

[LoneStar]

wire it as per Lucas which it needed for the podtronics reg

Yes, that's what I've done. And it may actually be OK, and normal to put out only 0.4 V at 1000 rpm; it just seems suspicious. I don't have a means at hand to spin it faster, unfortunately.

 

[Bill Thomas]

I can't find the mod' to change from Miller to Lucas,
Sure it's in one of the old books ?,
But just had a look in thevincent.com
And it says if you have not got the full voltage going to the Field coil
It won't give out much, So is the battery a good one ?,
Maybe a dead cell ?.

I myself can't be bothered with the old stuff,
A Mcdougleator or Walkernator To me , Is the way to go,
Too many of us have had to do the MAD ride home with NO Lights !!,
Very Dangerous now , Tricky even then !.

I remember in the 70 s Buying all new standard stuff,
And it didn't last long, If you are going to ride with any sort of rev's.