Generator charging rate

At a fast idle or above my ammeter shows a charge rate of 20+ amps when the light knob is set on the H, D, or B. Zero charge when set on the L. Just installed a new battery recently. Regulator points close on the H, D, & B. Open on the L. Should I be concentrating on the regulator, or should I open up the electrical box and see if the problem is there? Would appreicate any help. Thanks

The L position is for low charge and H for high charge. In times of limited tractor use the H position is used,when the tractor is used long days the L position is used. If yours will hold even with the lights on I wouldn't touch anything. Early M's and H's had a third adjustable brush in the generator which the operator would adjust for seasonal operation

r4etired: Thank you. May I assume that since there is no charging when set on the L, it is because the new battery is fully charged?

You have (2) problems Doctor:

1 - The field resistor on the light switch has failed. This will cause the generator stop charging with the switch in the "L" position. Replacing the resistor should solve the problem. (Unfortunately I cannot recall the correct resistance - seems to me it's about 5 ohms but I'm uncertain...)

2 - The 3rd brush in the generator needs to be adjusted to reduce the maximum charging rate to 15 amps or so. (Rotating the brush AWAY from it's nearest neighbor reduces the charge rate.)

----

Alternatively you can abandon the manual charge control and cutout relay and replace it with a voltage regulator. A VR will automatically limit the maximum charge rate to a safe 15 amps or so. Also it will do a better job keeping the battery charged.

Note! With a regulator installed the L and H positions on the light switch simply become 2 "off" positions for the lights.

Nope! Even with a fully charged battery the cutout relay should still pull in and the ammeter indicate 2 - 4 amps charge with the engine running at governed RPM.

Bob M--Thank you. Examined the generator for the third brush adjustment this afternoon and I don't think this generator is so equipped. Will look again. Also, will open the electrical box and check the resistor.

I'll add to the info by saying that if you have a two brush Generator, and if you have a real regulator, with more than two terminals, at least a BAT terminal, A Gen terminal, and a F or Field terminal, it may also have an L terminal. (Called a Load Terminal)and if some how the light switch is hooked into the system, it should not be. The light switch is probably correct for the year, but someone installed a voltage regulator and then left the old light switch manual charge regulation system control hooked into the regulator.

If the VR looking thing has only TWO terminals, the Light Switch should be hooked up, and it does have a burnt out resistor mounted on it in the Box because it is not charging in the L position, and will charge at max when in any other position while running.

Only one fat #10 GA wire should run between the Bat Terminal on the V Reg, and the Non Battery side of the Amp Gauge. If it has a L terminal, That could be hooked to the Light switch to the circuit in the switch that supplies lights.

The four position switch is two seperate switches with a common knob. One is control of the charge rate L H (it is a grounding circuit and connects through the switch to ground. The other is to control Lights D B and it is supplied with Voltage for the lights. and is not grounded at all. Mixing the two will cause smoking parts.
I hope this helps, JimN