I have an old tractor that is 6v system.

What happens if "somebody" put a 12v battery in it?

Depends a lot on the type of electrical accessories found on the tractor. While the battery is still at 12 volts, somebody will have a very peppy electric starter and very bright lights until they both prematurely burn out. I suspect that your ignition coil and ignition condenser will not be on speaking terms with you, and any electrical gauges will be unhappy. Then there is the question of what a 6 volt charging system will do with a 12 volt battery.

Plenty of pre-'55 American cars were originally designed with 6-volt systems. Many were converted to 12 volts, with most of the above referenced ignition/charging components replaced with 12 volt versions, and 12-volt to 6-volt voltage stepdowns were wired-in to preserve the original 6 volt gauges and radios.

IIRC you could put a 12v battery in the ford 9N's for a while before something stopped working....voltage regulator IIRC. (they were light on instrumentation).
Often, 12v is what it would take the start those... again IIRC - I've never been a good tractor guy.

But the above list is a good check - if it all works now, put a 6v back in and keep running it.

-John

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Husband, Father, sometimes friend =)

It's a 4 cal, gas, IH, McCormick, Farmall Cub. It's mid-60's as far as I can tell. It had a 12v battery for about a year before it started to fail. I checked on the Internet and found it was designed to be 6v.

The lights don't work. The gauges don't work (except for the "charge") gauge. I took the 12v off and put a 6v in and it cranked. The 12v was deader than a week old corpse.

I put the 12v on a trickle charge and it went to 100%.

I'm thinking that the voltage regulator continued to put out 6v at whatever amperage, which was not sufficient to recharge the battery and that's why it was dead.

I don't know whether it's a generator or alternator. If alternator, I'm guessing that the field charge was wrong -- would that fry the alternator? I dunno. If it's a generator then it's no problem, right?

I know, I know, I should find out more about the tractor -- like an owner's manual or something. Yes, I'll do it, swear!

It's an excellent tractor for 2 things: Planting and cultivating (in a small garden). The offset seat allows me to track right down a row and the belly implements let me monitor everything as it happens. But the truth is, I suck as a mechanic. And I don't have a mentor. So I learn by mistakes. One at a time.

Cub-Owner's Manual

The battery will act like a six volt battery.

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No clue about your particular tractor, but if you lick the contact on a 9V battery it tingles