Comet Electrics

[timetraveller]

The question is, "can you do it now?"

 

[poor1]

Hooked a new 6 volt battery up to the comet but no idea which wire goes to positive or negative. Hook it up one way and lights work with ammeter needle sitting high then when I switch switch connections lights still work and ammeter sits just below Half way which seems more normal. Any ideas?

That was the original question

 

[timetraveller]

If the amneter is showing a a discharge when the lights are on then the amneter and battery are the right way round. If showing a charge then one of them is the wrong way round. None of that means that the dynamo has the correct polarity. There is plenty of information on here, or in any of the old books that deal with motorcyle electrics, to make it easier.,

 

[poor1]

'None of that means that the dynamo has the correct polarity' That is the precise problem and I imagine the question that was being asked in the first place,.

 

[timetraveller]

I'm not sure whether something is being taken here or not! Once the battery and lights give the correct discharge on the amneter then all one has to do is start the engine and see if you get a larger discharge or start to balance the load. If the latter then all is working as it should. If not then flash the dynamo and you have been told how to do that on here already.

 

[Martyn Goodwin]

As someone who has had a life long fascination with 'how things work' I am sometimes surprised but not shocked by questions like yours.

You really need to understand the basics before you start tinkering. Your local library may have a few books that could help out. Then there are web sites like this https://www.instructables.com/Electricity-2/ that might be of use as well.

The VOC published a small book that is invaluable, not sure if it is still in print, but you may find second hand copy is you go looking , Its called "Motorcycling Electrical Manual" written by Bernal Osborne.

For research use only I have attached a scan of Chapter one which answers your questions. If you can make no sense of it it may be best to engage the services of a professional auto (car or bike) electrician.

Martyn

 

[oexing]

For testing the polarity my idea is to remove the dynamo drive sprocket or gear, connect D and F with positive battery , negative to earth and see, what direction the dynamo spins like a motor. When direction is same as driven by engine all is well. If wrong direction, swap internal field wires - or accept positve earth on bike. Am I wrong with this logic ?

Vic

 

[Bill Thomas]

I have tried to keep out of this, I am rubbish with electrics,
But this sticker came with every exchange dynamo, When I was a lad !!.
Working on Cars.
6v will be the same, But do it OFF the Bike before fitting !!.
Good Luck, Bill.

 

[oexing]

Hmmm, that would be an easy conversion to negative earth. Can´t quite believe it - but then, never tried . . . .

Vic

 

[Bill Thomas]

Can't tell you how long that has been in my tool box,
I like to keep these things , Just in case !,
My memory is getting worse, Now where did I leave the Wife ?.