The Stovebolt Site Forums The Shop Area The Electrical Bay How to identify a 12V system?

We are trying to start a 54 Chevy 4400 that is missing the battery, so don't know if it is original 6V or has been converted to 12V. What are the tell-tale signs to help me indentify which system it is. Also, in either case it is always negative ground, right?

Might try checking the generator for an ID/Spec tag.

BTW where are you at here in GA?

If it has an alternator, it's 12V. The regulator on my generator equipped truck has "12V-N" stamped on the base. (12 volt, negative ground) This code is found on the right side of the reg as you look at the firewall, next to the screw that attaches it to the firewall.

They do make 6volt alternators too but most go to 12 volt if going to the effort of changing. But check part number as suggested just to be sure.

6V alternator? They have to be pretty rare. What automotive application used that?

Here's another idea. Check to see if it has 12V headlights. Unless the vehicle was only used in the daytime, they would have to replace the headlights when they converted to 12V.

If it has a generator, the 12v generators are marked as such at the top of the oval "Delco-Remy" tag - at least every one I've seen was marked this way. None of my 6v generators are marked as to voltage.

Thanks, guys. I'll head out to the farm this afternoon and check a little closer.

5th Ave from the links section advertises a 6-volt alt. Not sure what the original applications are though. Changing from 6 to 12 is trivial anyway so not sure why anyone would go to all the trouble and expense to get modern but keep pushing 6 volts. but it's there if you want to.

I see what you mean, Dennis. I bet that they use a 12v core and drop the voltage to 6v in the internal regulator. The instructions mention that alternators weren't common until the 60's (after 6v systems were already obsolete).

I agree with you; why bother with a 6v alternator? You would have to ask someone who bought one.

Also look for a resistor between hot wire and coil. six volt system won't have one.

HERES THE EASY WAY, CHECK OUT THE TRUCKS BULBS HEADLIGHTS, TAILLIGHTS ETC. Heres a few #s
12 VOLT# 1156,1157,57,67,1895,2056,2057,53,89,90
6 VOLT# 63,1129,1154,55,51,87,63,81,82
I hope this helps you out!

All good tips plus the original Delco generator tags were either red or black depending on 6 or 12 volts , of course I cannot right now recall which is which .

Just use a 12 volt battery until you get it running and starting good. I used a 12 volt to get my 54 started so I could evaluate the engines condition, just didn't turn on any lights. It also helps it to start, after a long rest, if the engine cranks over faster.
Just my opinion,
Scott

Be careful, Scott. You can fry your fuel gauge starting a 6V truck with a 12V battery. It's on when the ignition is on.

I made a 6V alternator a while ago by changing the diodes and voltage regulator. I was having reliability problems and it worked for a while until I decided to convert to 12V. Parts are available on line, you can convert a GM 10si alternator to 6V for about $25. It worked pretty good until a short fried the regulator. I changed the harness and used a 12V alternator.