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-ve earth to +ve earth conversion.

Posted: Tue Feb 12, 2013 11:26 pm
by ferret76
G'day All, I have just been given a brand new generator, unfortunately it is -ve earth and my car is +ve earth. I know there is a way to reverse the polarity. Firstly:

How do you do it?

Secondly:

Is it a good idea or is it going to cause problems?

Re: -ve earth to +ve earth conversion.

Posted: Wed Feb 13, 2013 12:30 am
by bmcecosse
What kind of 'generator' ? Almost ALL alternators are -ve earth, and any dynamos I have experienced can be polarised to work either -ve or +ve earth.........

Re: -ve earth to +ve earth conversion.

Posted: Wed Feb 13, 2013 5:08 am
by ferret76
bmcecosse wrote:What kind of 'generator' ? Almost ALL alternators are -ve earth, and any dynamos I have experienced can be polarised to work either -ve or +ve earth.........
Looks like it is a Lucas C40.

Re: -ve earth to +ve earth conversion.

Posted: Wed Feb 13, 2013 8:04 am
by Trickydicky
Here is a step by step guide.

http://www.mmoc.org.uk/index.php?page=322

Re: -ve earth to +ve earth conversion.

Posted: Wed Feb 13, 2013 2:32 pm
by bmcecosse
Oh well - a C 40 can work either way, no need to change the vehicle polarity.

Re: -ve earth to +ve earth conversion.

Posted: Thu Feb 14, 2013 11:15 am
by mike.perry
You get slightly less electrolytic action across terminals with neg earth

Re: -ve earth to +ve earth conversion.

Posted: Thu Feb 14, 2013 8:53 pm
by bmcecosse
I think what was being asked here - is how to change the DYNAMO polarity....not the car :oops: :roll:

Just join the two terminals on the dynamo with a length of cable - and then touch the cable to the non-earth terminal of the battery.... It will run as a motor provided the fan belt is not on of course.......... And that action is enough to reverse the polarity.

Re: -ve earth to +ve earth conversion.

Posted: Tue Feb 19, 2013 1:58 am
by ferret76
Cheers BMC, that's what I was looking for.