Newbie question: 6 volt vs. 12 volt system
 

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I'm the new proud owner of a 1950 F1. I am also a relative newbie at these old trucks and my mechanical knowledge is limited. I will probably have many questions in the coming days many of which will probably be just plain dumb. Here goes: when I bought the truck the battery was dead and wouldn't hold a charge. Before I took delivery the previous owner agreed to replace the old battery (it was dead and wouldn't hold a charge), which he did with a new 12 volt battery. He clearly didn't understand 6 volt versus 12 volt systems, but claims he was told by the guy at the auto parts store that this truck had been converted at some time from 6 volt to 12. I have cranked the truck a few times with the new battery and its working fine, but I know enough to know that IF the prior owner is wrong, and the truck has NOT been converted from 6 to 12 volts, I have the wrong battery and need to replace it with a 6 volt before doing damage to the truck. So the question is this: how do I determine if the truck is running on 6 volts or 12? Again, I apologize in advance for my ignorance but I'll never learn without asking and doing. Thank you in advance.

Welcome to FTE. Beautiful truck. :-X22
Does the truck have a generator or an alternator? If alternator, it has been converted.
Is the battery hooked positive to ground or negative to ground?
You've "cranked" the truck. Does the truck run?

Multiple ways. Here's a few. Does the truck still have an original generator or an alternator? Pull out one of the rear tailight bulbs and tell us what number is stamped or printed on the bulb. Or better yet, show us a picture of the engine bay, and we'll probably be able to see something that will help us answer the question. It's not a stupid question at all. Welcome!

Ray beat me to it. Dang that is a pretty truck.

Guys thanks for the quick responses. I'll be home in 45 minutes and I'll shoot a few pictures under the hood. In answer to one question: the truck runs very smoothly. So good in fact I have had a hard time restraining myself from driving it before I can get it registered. Thanks again and more information and pics will follow shortly.

More pics.
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Welcome to FTE!

There are no dumb questions here. This is one of the friendliest forums you'll ever find.

Having an alternator is usually a pretty good indicator that it has been converted to 12 volt, but not always. There are 6 volt, positive ground alternators. Likewise, there are 12 volt positive ground generators. So having a generator doesn't always mean it's still 6 volt.

The 6 volt alternators are usually very expensive and therefore kind of rare. I'm just saying it's a small possibility.

I think Doc is right. Checking the bulb numbers, or even checking to see if the coil or starter relay say 12 or 6 volt might tell the story. Some mechanics will also leave a list in the glove box telling what parts have been changed. For example: what brake pads fit a disk brake conversion.

If you have held the brake pedal for more than 30 seconds and the tail lights didn't burn out, you're probably good to go.

Note: No fair! You added pictures while I was typing.

What battery post is grounded to the block?

Note to FTE buds: sure looks like a stock generator to me.

Looks like neg. ground. Pos going to starter relay. Was looking for a ballast resistor.

Tail light bulb says T1157 China 7H.

If you look at the top picture you can see the + on the top of the battery. It's running to the starter relay but it looks like the clamp was beat down onto the post.

I agree on the generator. It has an oil port for the rear armature shaft bushing. It's no guarantee, but I've never seen one on a 12v generator. That's just my experience, your mileage may vary.

Jacnat, I would be careful with the light bulbs until you figure it out.

That would be a 12v bulb.

Hey guys, where is the voltage regulator mounted on a six cylinder truck? I was voting 6 volt until he told us 1157 on that bulb. I agree with above. That sure looks like a stock 6 volt generator. Based on his story about the P.O., I don't think we can trust the position of the battery or how it's hooked up. Jacnat, can you stick your camera up under the dash and snap 2 or 3 pics of the wiring harness? Also, tell us if the wire running from the coil to the distributor is hooked to the negative or positive lug of the coil?

Hope this helps. Thanks guys.
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What do you mean by be careful? Thanks