Dynamo/Charging issue

[Mac985]

Hi there,
I’m wondering if anyone has any experience with dynamos on old engines that could shed some light on our situation.

Our engine is running absolutely spot however we are not getting any charge from the dynamo.

I took the dynamo out dismantled it and realised one of the brush springs had snapped so we ordered a new set of springs and decided just to change the brushes and give the commutator etc. a clean up seeing as I was in there anyway. Once this was done we tested the dynamo on the bench for continuity etc. all readings came back normal.

We were all excited and refitted it today hoping that this was it we were finally going to be fully up and running and low and behold it’s still not charging.

We found a trick in a Lucas Dynamo workshop manual for repolarising it by quickly shorting it from the boat earth. This didn’t seem to help either.


Any help would be greatly appreciated, I know Dynamos are an ancient forgotten technology but this is what I’m working with at the minute

 

[B27]

Dynamos and their regulators are quite subtle things.
There are a few people in the world of classic motorbikes who understand them.
It is not any easy thing to sort out over the internet.

 

[Plum]

Hi there,
I’m wondering if anyone has any experience with dynamos on old engines that could shed some light on our situation.

Our engine is running absolutely spot however we are not getting any charge from the dynamo.

I took the dynamo out dismantled it and realised one of the brush springs had snapped so we ordered a new set of springs and decided just to change the brushes and give the commutator etc. a clean up seeing as I was in there anyway. Once this was done we tested the dynamo on the bench for continuity etc. all readings came back normal.

We were all excited and refitted it today hoping that this was it we were finally going to be fully up and running and low and behold it’s still not charging.

We found a trick in a Lucas Dynamo workshop manual for repolarising it by quickly shorting it from the boat earth. This didn’t seem to help either.


Any help would be greatly appreciated, I know Dynamos are an ancient forgotten technology but this is what I’m working with at the minute

I remember assembling a dynamo over 50 years ago. There was a technique of fixing the brushes so they were lifted off the commutator before assembly and then releasing them once the rotor/shaft had been inserted. If this was not done correctly the brushes did not spring back and contact the commutator.

 

[Portofino]

Usually the regulator dies first .Have you checked that yet ?
Thinking you said you bench tested the dynamo before fitting it back and it was ok - if I understood your post #1 ?

You can get modern solid state insides , fit and forget nowadays .

[I have classic cars / bikes btw .]

 

[Mac985]

Hi guys,
Just a little update, we change all the spade connectors going into the dynamo and regulator we also added a new ammeter. This along with a bit of adjustment on the regulator and we have 14.4 volts at cruising speed! 13.3v at ticking over.

Thanks for all your input.