Running my 6V cub on a 12V Battery

I recently bought a 1948 cub, and the previous owner had replaced the 6V battery with a 12V and switched it around so there was a negative ground...The starter cranks great, fires up well, lights work, nothing out of the ordinary...

Am i set up for disaster?
What should i do?

Thanks
Nate

Well if its an older cub the only problem will be is if its battery ignition the coil can/will burn out faster then it would on 6 volts. Also the generator will not charge the battery.
Hobby farm

You can buy 8 volt batterys that will charge from your 6 volt generator. Grant you they cost more but it might be your fix.


Also check the timing on the motor , to much timing will make them hard to start.

Check around the coil for a ballast resister, If installed it should be roughly 4 inches long and have one wire attached at each end of it. It will be made of a white ceramic material. If not equipped you will want to install one. This will cut the 12 volts down closer to 6 volts for the six volt coil. If still equiped with the 6 volt generator it will not charge the battery, But the tractor will still run for long periods of time without a charging system. My personal opinion is to leave our antique tractors with the 6 volt system that they were designed with. If the engine and electrical system is all in good working order, and the tractor tuned up properly , They will easily start every time with the six volt sysytem.

Depends what else he did as part of that conversion. If you've got a magneto for ignition, it can't do any harm there. If battery ignition, he should have put either an inline resistor on the hot wire to the coil or put in a coil with an internal resistor.

As far as charging, has it got an alternator or a generator?

If your Cub has a magneto you need not concern yourself with the ignition - it is fully independent of the rest of the electrical system.

If it however has a coil/distributor ignition it must have either a ballast resistor added to the coil primary or a "12 volt" (self-ballasted) coil installed. (As the others point out the stock 6 volt coil and breaker points will not last long on 12 volts.)

As for the generator, simply check the ammeter while the engine is running at speed. If it indicates charge (needle to the right side of center) the battery is charging. However if it is centered or to the left of center your battery is not charging - it will eventually go flat on you.

If the ammeter is inoperative, you can also check generator operation by sticking a DC voltmeter across the battery posts with the engine running. If the battery is charging it will read 14.0 volts or a bit higher.

----

The fact the headlights work suggests whoever did the conversion likely already took care of the electrical issues including replacing the original bulbs with 12 volt bulbs. Otherwise the original 6 volts lamps would have quickly burned out the first time they were used on 12 volts.

Don't crank on the starter too long at a time. 12 volts going into a 6 volt starter will burn it up if you crank on it for extended periods of time trying to start the tractor. I was going to convert my cub to 12 volts, but I couldn't find an alternator that would fit under the hood. Other choice would be to have the generator rewound for 12 volts.