Battery not charging

[[email protected]]

I could use some help solving a puzzle. (a puzzle for me at least!) with the engine running i'm showing a slight discharge that doesn't change even with a higher rpm-- the problem just appeared and i'm not sure where to start. Suggestions ?

[nkaminar]

Have you tried adjusting the charging rate by moving the third brush down? The third brush is the only one that rotates around the axis of the generator. It controls the charging rate.

Another answer may be that the cutout, that sits on top of the generator, is not cutting in to allow the generator to connect to the battery. If it is the old style with points, then the points may need to be cleaned and polished up. If it is the new style that is electronic then it may need to be replaced. Measure the voltage with a multimeter at the generator side of the cutout to see if it is 7 volts or higher. If the cutout is bad do not run the generator for any length of time as the voltage can build up to the point where it can cause damage.

Another possible answer is that the generator is bad. Normally they just need new brushes and the commutator shined up. Measure the voltage, as above, and if there is 6 or less volts then the generator is not generating.

Move the third brush before assuming the generator is bad. After moving the third brush, observe the charging rate (or discharge) at a fast idle, about 1,200 rpm.

Here are some links that may help:

http://modelabasics.com/Cutout.htm
https://www.mafca.com/downloads/Semi...ex%20Janke.pdf
https://www.youtube.com/watch?v=r_GR3jseCkk

[HDowse]

Try bypassing the cut out with a clip lead after the engine is running, check the ammeter to see if it’s charging.
If the generator is new or rebuilt it may need to be energized (I forget the more common term). Others will fill in the simple details that escape me right now. Must be pre-Christmas stress syndrome. Merry Christmas everyone.

[Big hammer]

Maybe the generator has become disconnected from the battery, cut out, blown fuse, bad wiring connections.

Don’t operate for very long or you can burn up the generator, the generator can produce about 40 volts in a uncontrolled condition!

[Model A Ron]

Could it be you have a bad battery? How old is it? Have you had it tested?

[HDowse]

Sponsored Links (Register now to hide all advertisements)

A follow up to my previous post. You may need to polarize the generator in addition to the other suggestions. It’s an easy operation: Here’s a link to a previous 'barn discussion.
https://www.fordbarn.com/forum/showthread.php?t=40198

[Badpuppy]

Originally Posted by [email protected]

I could use some help solving a puzzle. (a puzzle for me at least!) with the engine running i'm showing a slight discharge that doesn't change even with a higher rpm-- the problem just appeared and i'm not sure where to start. Suggestions ?

I would guess cutout gone open. Yeah, don't run it long that way.

[Aretino]

"Flashing the Field" is common terminology for polarizing a generator.

[redmodelt]

Start with the basics, check the generator output with a meter, motor running. Then check the battery side of the cutout, do you see battery voltage there? The battery side is hot all the time.

Calling it "Flashing the field" or "Polarizing", could be a regional or industry thing, with many just saying polarize. You are flashing the field to polarize the generator.

In any case, it is done to recharge the magnetic field after rebuild, sometimes if needed, or change the position of the poles if you were to change the ground from positive to negative or the reverse.

[Patrick L.]

Another check of the generator is to see if it will motor. Just loosen the belt, apply power to the generator and see if it motors. If it spins [slowly] then 99% of the time its fine.