Farmall B 1946 Running off Battery??

eegj1 · Oct 3, 2010

I have a B that has been sitting up for more than 10 years. I got it started and running, but seems to be running off the battery. I have never worked on a B. Still is 6 volt. Any ideas?

Thanks in Advance

Lumpie · Oct 3, 2010

Start the tractor and then pull a cable off the battery. If it dies, then yes it's running off the battery, generator's not working. Don't really know what you're asking with your question.

Brownie 450 · Oct 3, 2010

If it has a magneto, it will run with the battery disconnected.

eegj1 · Oct 3, 2010

Thanks. What steps did I need to take to check and magneto?

MNGB · Oct 3, 2010

Are you saying that the generator is not charging the battery, if so it could be the voltage regulator or if its the older 3 brush gen with just a cut out the cut out could be bad or the generator could need to be flashed. Is the battery connected for positive ground or negative ground?
GB in MN

James Williams · Oct 3, 2010

eegi1,Dont never pull off a cable with the motor running,

jimmy

eegj1 · Oct 3, 2010

How do I flash the generator?

Janicholson · Oct 3, 2010

If it is running you can assume the ignition is working. If it has a magneto ignition it is a self powered system that has no battery power hoked to it at all. It has a small internal generator inside the housing that with other parts makes timed spark to each plug.
It is recognized by being an all in one unit. The Cap from which the spark plug wires originate has a center terminal connected by a short spark wire that goes to the rounded cover on the top of the unit.
A distributor will have that wire going to a separate coil on a different bracket. (usually a cylinder of some description.
A mag is connected to a kill switch that grounds the mag side terminal, shutting off spark.
A point and coil distributor has power going to the separate coil from the ignition switch.
On Farmalls the switch for both look the same from the button point of view, but one is a grounded switch with only one terminal, and the other gets power from the amp meter and has two terminals.
The trouble shooting guide included will help. Jim
John T charging analysis

Janicholson · Oct 3, 2010

John T guide included above in my other response explains it. Do not intentionally disconnect the battery while running a vehicle. In some cases it will be OK, but we cannot see what you really have and if done to some systems can let all the smoke out. Jim

36 Coupe · Oct 3, 2010

What does the ammeter read when the engine is running.

mkirsch · Oct 4, 2010

Slow down here a little, folks. It appears "eegj1" is a little "green" when it comes to tractors.

Okay eegj1, here's the deal: Most all Farmall tractors built before 1950 will have a magneto ignition system. Magnetos do not need a battery to run.

Magnetos do not charge the battery, either. All they do is send sparks to the spark plugs.

This is what a magneto looks like:

If your tractor has one of these on the left side of the engine, it is not running off the battery. It must look EXACTLY like the unit in the picture, not just a black cap with a bunch of wires running every which way. A distributor looks similar but there are distinct differences if you look closely. The devil is in the details.

If the tractor starts to your satisfaction, and runs properly, there is nothing to check. Your magneto is funcitoning properly.

eegj1 · Oct 4, 2010

Ok. Getting somewhat clearer. Mine has a 6 volt coil.

Farmall B 1946 Running off Battery??

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