voltage regulator system for positive ground

ccaissie · Feb 3, 2014

Sorting out a Ford 8N that has promise. There"s an automotive alternator on the port side, with a dangling wire and clip from the battery terminal. Looks like the owner had intermittently attached and detached it to regulate the battery charge...anyway, there"s a new voltage regulator with 4 pins nearby, but no wires anywhere.

First, I assume we"re running 12volts, as a 12Volt positive ground connection turned the motor over.

So, do I need to know anything special about this setup? Will the existing alternator know how to create power in a positive ground system? Will I just hook up the regulator as if it"s standard modern automotive ground system?

thanks,
C

David G · Feb 3, 2014

Most alternators are negative ground, why do you think this is positive?

ccaissie · Feb 3, 2014

i think the system is positive ground...I hooked it up that way and the starter worked. Did it run backward? didn't notice.

rvirgil_KS · Feb 3, 2014

Starter doesn't care, it will turn same direction regardless of whether it's connected positive or negative ground.

Sounds like someone may have removed generator, left regulator in place and cobbled up or didn't understand how to wire the alternator.

Also depends on alternator. Later ones had built in regulator, early ones used external regulator.

mEl · Feb 3, 2014

If you hooked a 12V neg alternator up to 12V pos ground you most likely destroyed the diodes in the rectifier system within the alternator.

The wire with the clip on it was most likely used to manually excite the alternator, a simple touch of the right terminal will start it charging and stay charging till it is shut down, next time the process has to be repeated.

Unless you can determine otherwise the alternator was probably neg ground as that is the standard, however they can be built for 12 V pos. or even 6 V applications. I would reverse the battery and try the system by running it and touching the regulator blade with the clip and see if it will charge, you may have to take it and get it tested.

If it is a Delco,they are very easy to wire an exciter circuit up to

David G · Feb 3, 2014

The starter does not care about polarity, and you probably did ruin the alternator hooking this up.

I would start from scratch, discuss your goals on the site and you will get good advise. I am a fan of the internal regulator alternators that take 3 wires.

ccaissie · Feb 4, 2014

Never hooked it up, so I'll assume the previous
owner went to 12V negative ground. I'll see if the
engine rotates properly w/ neg ground.

Once I get the thing running, I'll start hooking up alternator and see what i get.

Thanks, C

voltage regulator system for positive ground

ccaissie

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David G

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ccaissie

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rvirgil_KS

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mEl

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David G

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ccaissie

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