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MickO

6 Volt Positive earth to negative earth conversion

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The previous owner spent a nice sum of money on a Dynamo rebuild (£500 UK) including new electronic regulator. I was having charging issues so i discovered that the Dynamo was set up as neg earth unit with a new 22 amp neg earth electronic regulator fitted. Now i know why i was having charging issues. I got a local company to check the charging and the Dynamo is working perfectly in the neg earth mode.  I am thinking that the most cost effecient way to go now is to change over to neg earth from pos earth. Its a 1934 flathead so no radio clock etc. I need to reverse polarity on the coil and reverse the ammeter wires as well as the battery terminals. Any advice on this and other things i might have to consider. Any advice greatly appreciated.

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Are we assuming that you have it hooked up positive earth at the moment  ?

 

If you're now choosing to swap over to negative earth then yes to all you have said above.

 

What concerns me is your reference to electronic regulator, because in addition to the above you would normally need to change the generator (dynamo) field polarity, which is a simple enough task, but I would be cautious without knowing the wiring details of the regulator; perhaps best left to a professional. 

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Hi hchris, thank you very much for your reply. Yes she is hooked up to pos earth and i was having charging issues, when i discovered that the Dynamo had been fitted with a new neg earth electronic regulator as well as rewound armature, field coils, new bearings and brushes etc. so i had a pos earth system with a neg earth dynamo regulator set up. Strange i know. The starter was also rebuilt at a cost of £325 sterling. The dynamo and regulator are charging perfectly in neg earth so i dont see the point in changing back to pos earth on the dynamo regulator etc, it would seem to be easier and more cost efficient to go neg earth. will there be any issues with fuel sender unit ?, will i have to change polarity on that as well ? 

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Ok so I'm assuming that the amp meter is reading correctly ? that's a positive indication whilst charging  ?

 

If so then there's nothing left to do, gauges etc. aren't polarity sensitive, nor lights, starter etc. You said the coil leads were swapped (hot wire to the + terminal, - wire to the distributor) so that's good; can't think of anything else.

 

I'm still a little confused about your "negative earth" regulator, the regulator doesn't care about polarity, it's function is simply to control the current flow as demand rises and falls plus ensuring the battery is charged. What really determines the difference between negative and positive electrics is:

1. how you have the battery  terminals coonected, and

2. the polarity of the internal field windings of the generator (dynamo)

 

So in all of this, so long as the battery connections and generator polarity are a correct everything should run just fine.

Edited by hchris
Add query (see edit history)

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Hi hchris i think that when the Generator was rebuilt it may have been presumed by the company doing the work that it was a neg earth system and then set it up that way by flashing the generator as neg earth and then fitting a new negative earth electronic regulator which i am led to believe will only work as a neg earth unit. Given that it was fitted to a pos earth set up i am surprised that it was not damaged in this set up, but it seems not.  

Neg earth 6 volt electronic regulator.jpg

Edited by MickO (see edit history)

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