12 Volt system, how do you tell?

Mon Apr 12, 2004 10:32 am

My cub has no generator or altenator on it. The previous own says he was running on a 12 volt battery????

1. How do you know if the cub is running on 12 or 6 volt system with no battery, generator, altenator or lights to tell you.

2. I want to run 12 volts, is there a conversion or instructions available and if so, can anyone suggest an Altenator

I visit a lot of forums on the net, from Model A cars, Ford tractors and My own Shay Roadster Forum(Model A replica's) but, I have to say this is the nicest and friendliest forum that I have ever had the pleasure of visiting.

Mon Apr 12, 2004 10:45 am

With no generator or alternator to keep the battery charged, you must have a magneto ignition system. If that's the case, all you have in the battery circuit would be the battery and the starter. Of course, even a battery ignition circuit would last quite a long time between charges since all it is doing is supplying energy to the ignition. So, if there is an external coil, see if it is marked 12 volt or if it has a ballast resistor attached.
If you don't have a voltmeter of any kind, you can look at the battery to see if it has any markings on it. Also a 12 volt battery will have 6 cells so there should be either 6 individual caps or 2 - triple caps on the battery. A 6 volt battery would have only 3 caps. If it is a sealed battery - with no caps on top, it is probably 12 volt.
One other trick you might try is to take a spare 12 volt bulb and connect it temporarily across the battery terminals. If it shows normal brightness, you have 12 volts, if it just glows, it is probably 6.


Mon Apr 12, 2004 4:07 pm

Perhaps I should go a little further in my explaination, I have the bracket attached to the engine for a generator or alternator but whatever was there is missing. The battery and lights are missing from the tractor as well. I Will check that external coil and I think I saw a ballast resistor behind the dash.

thanks again,

Mon Apr 12, 2004 5:03 pm

OK, let's put it this way then: Cubs prior to serial number 224401 were 6 volt positive ground. From that number & up were 12 volt. This change came in 1964. The ballast resistor I was talking about would be located near the coil, not behind the dash. The resistor you are seeing is either for the headlights or the charging system.

Mon Apr 12, 2004 7:44 pm

Ok, time for my two cents. Big Dog has it right as usual. Sooo my point would be, if you Cub was originally a 6volt system - put it back to 6 volt. There really is no advantage to converting over to 12volt.

Jethro is in the beginning stages of his restoration and currently has (had) a 12 volt setup complete with the destroyed hood :roll: :? I guess the PO's BIL was not too :idea: :!:

Alton now has a distributor minus the cap and rotor as well as a POS alternator that no longer insults Jethro......

He is getting a new generator and a mag so he can sport the proper electrical system. :D

Mon Apr 12, 2004 11:11 pm

There really is no advantage to converting over to 12volt.

Well, it seemed in my case at least, that it was cheaper to just buy the 12v alt with the built in voltage reg. I guess it depends on how many components of the 6v system are missing, and if you want to go back original. Sometimes the previous owner sets the wheels in motion for you, as was in my case.