farmall m charging?

Last night I was working on my M and posted a few ?s. Well I have them answered, my question now is I'm not sure my battery is charging (battery is new) ..The ammeter goes to the right about 7-8 amps like its charging but when I put my meter on the battery I only get 6.2volts.. I get 6.6 volts between GND and the A on the generator at full throttle. I adjusted the 3rd brush about 3.2 bars from main brush. Shouldn't the 6.6 volts go all the way back to the battery? How am I getting a voltage drop..loose connections or should the genny voltage be higher...how much can I adjust the 3rd brush?

IFFFFFFFF the Cutout Relay is latching in/closed, then the gennys output on its ARM post is effectively tied to the battery via closed cutout relay and ammeter and Id expect it to be close to battery voltage less the small ammeter and relay and wiring voltage drop...

Ifffffffff the wiring is correct and the ammeter is working, that 7 to 8 amps you mention sounds fine and after running a while Id expect it to drop back. Buttttttttt if the batterys taking a 7 amp charge Id expect the battery voltage to be rising from 6.3 to 6.5 to 7 or so (your stories arent jiving lol)

To me an accurate way of seeing if the system is charging is a voltmeter on the battery. Id expect it to be 6.3 volts not running but rise to at least 6.5 to near 7 or a tad more at fast RPM once started.

MY THOUGHTS: Not knowing how accurate your meter is I wonder if the cutout relay is pulling in?? (That could explain a difference in battery versus genny voltage) If the genny isnt putting out enough voltage the cutout relay may not latch in to tie the genny to the battery. (but that 7 charging amps sounds like its working???)

SEE WHAT HAPPENS IF YOU TEMPORARILY DEAD GROUND THE GENNYS FLD POST??? That puts the genny in high charge and if the battery voltage rises then (but not otherwise) I suspect the LHBD switch is bad,,,,,,,,or isnt well grounded,,,,,,,or the wires bad from FLD on genny to the LHBD switch. If shes still not charging at fast RPM with the FLD dead grounded, leave it grounded and by pass jump across the relay (connect BAT to GEN/ARM) n see if she charges then????? With the FLD grounded and the relay by passed you have effectively ruled out any relay or LHBD switch problems so if she still dont charge (if all is wired right) the genny must be at fault..

The closer the third brush is to the fixed brush the higher the gennys output, maybe try it a bit closer????????

Work through my Troubleshooting Procedure to diagnose the problem

John T
John Ts Troubleshooting

I moved the 3rd brush closer..abour 2 bars....I get about 7.1 volts from GEN to ground..at WOT. And about 6.6 volts on the battery at WOT. About 6.3 on battery when off. I'm using a Fluke 333 meter and a Ideal clamp on ammeter both are very close.

Id be tempted to let well enough alone ALTHOUGH it seems a lot of voltage drop across the cutout and wiring and ammeter etc. Maybe measure the voltage drop across the relay i.e. from the BAT terminal on the Relay over to its ARM/GEN. If theres drop much there Id suspect the cutout points many be burned/carboned. I doubt much drop in the wiring or ammeter unless thers some loose or carboned connections.

There are limitation on how close the 3rd brush should be but Ive seen from 2 bars to 3.5 depending on which particular genny it is.

John T

I'm gonna let the genny where it is, I have a new VR ordered..the one I was using was off one of my H's cause the original VR on the M was kaput

Chimimg in here, I would check the integrity of the Gen output wire from the gen Arm terminal to the VR, From the VR bat terminal to the Amp meter, and from Amp meter to the Starter switch Bat terminal. This should be #10 stranded wire. If it sees more than a .5 volt drop across any link, or any through a terminal, I would replace it with new.
A fully charged battery is also needed to determine fundamental charging voltage and current. Otherwise the battery draw will determine both, and confuse issues. With the VR in place, do not connect the 4 position switch to the VR at all. (just a reminder) Jim