BN charging system question

Royse

Well-known Member
I'm trying to get the charging system working on my BN.
It's a mutt, roughly a '46 with a distributor ignition and a
cutout. Not a voltage regulator. 6V, positive ground of course.

Here's what I know - the generator motors and charges.
That ammeter is wired right and works both directions.
The aftermarket cutout that was on it was bad, so I replaced
it with a spare original style 3 wire Delco-Remy one I had.

I have added an additional ground wire from the block to the
generator case. I jumpered that ground wire to the cutout case.

Still a discharge on the ammeter and no increase on a
voltmeter across the terminals of the generator or at the
output of the cutout.

[b:14fdf6c602]It will charge if I ground the field wire.[/b:14fdf6c602]
I have the field wire on the generator connected to the field
resistor on the switch where the wiring diagram says it should
be. Field to ground with it hooked up cold measures 2.5 ohms.
Too high?

It has a 4 position light switch in it, with no dimming resistor.
The resistor may not matter since it has no lights.
Do I need to use a three position switch or did I overlook something else?
 
Simple check if you ground the field and it charges the cut-out is bad maybe its not grounded to the gen. Field from the gen goes to the four position sw at the bottom where the resistor is. The four position sw needs to be grounded also. I haveseveral of those systems and they do work if all componets are grounded well. Do you need the little resistor that hooks on the lite sw for dim lites.
 
Royse, if it charges when you dead ground the Gennys FLD post (tells me the genny itself is okay) but NOT otherwise and iffffffff the Gennys FLD post wires to the 4 position LHDB switch THE SWITCH IS BAD OR NOT WELL GROUNDED OR NOT WIRED CORRECT OR THE WIRES BAD FROM FLD ON GENNY TO THE SWITCH. I would expect in the HIGH charge position the resistance from the LHDB switch (where gennys FLD wire attaches) to frame ground to be near zero almost like dead grounding the Gennys FLD. In the LOW charge Id expect it to be from 2.5 to 3.5 or so ohms.

The 3 position light switch Off Dim Bright is for gennys that use a full fledged Voltage Regulator where the gennys FLD wires to it and NOT the light switch.

I thought the 4 position LHDB switched had TWO resistors, one for low charge the other for dimming the lights. The 3 position Off Dim Bright controls lights but NOT the charge rate, that's what the Voltage Regulator does. Sure you have correct switch and sure its wired right and has a terminal where the Gennys FLD wire attaches????

See what Bob M or Professor Jim have to say.

John T
 
As John T points out the problem's gotta be at the light switch.

Disconnect the field wire the at the resistor then measure resistance between the field terminal at the switch and ground:

1 - With the switch on "L" (turned fully counter clockwise) resistance should be around 2 - 3 ohms (I forget the actual value).

2 - Now set the switch to "H" (1 notch clockwise) - resistance should be 0 ohms.

If you don't see the above readings you have a bad light switch.

----

Suggestion: Unless you are a stickler for originality, replace the cutout with a 4-terminal regulator for a "Super" series tractor. Then set the 3rd brush in the generator to the maximum output position (set closest to the nearest fixed brush). Your battery will thank you(!)
 
Chased that on my '41 B Farmall.
Found the bolt that holds the ammeter box to the "steering" pipe wasn't making good contact and the lid of the ammeter box was not making good contact to the box.
The switch is in the lid and it must have a good path to ground thru the lid, the box, the pipe, and where the pipe attaches to the tranny. After shining everything up, I get about an amp with the light switch "off" and 10 amps with it in the first position. (hi charge)
I suspect you have a ground path problem.
 
For sure, the ground through the light switch is not happening. With it running at 2/3 throttle, and the light switch in H position, use a volt meter to "chase the voltage" starting with the terminal on the light switch, going to the light switch body, then to the cover of the box, then the box, then the steering support, then the tractor frame. at some point the voltage will go away. that is the location of the failed connection. As pointed out, the system is very simple. Were it mine, I would use a voltage regulator as Bob indicates. If you keep it original, you need to run it on H only for 5 minutes after starting, then turn it to L. If starting it more than once an hour, this is necessary. if only once an hour, leave it on L. The two positions for lights are both the same as H. Jim
 
Thank you gentlemen! I will do a little digging on
your suggestions and let you know what I find.

I neglected to mention the wiring is new, so I don't think I have
a bad wire, but the paint is new too, so a bad ground is a definite
possibility. Another reason I added the extra ground wires.

Bob M, I believe you are the author of the diagram I'm following.
On this tractor I am not a stickler for originality.
It is a parade tractor. I just can't let the battery run dead in the
middle of the street somewhere, nor do I want to boil it dry.
I will give some thought to converting it to a VReg.
Starts and runs fine on 6V, no issues as far as that goes.
Thank you all!
 
Hey Bob,I need a wire diagram for a '49 Farmall C that has 6volt pos.ground w/generator. Can you help me out?

Thanks,cuby
 
Royse, follow this trouble shooting chart on Farmall Bob's site.

07-Cutouttroubleshootingchartrev1_0.gif
 
It was a bad ground at the switch box caused by the new paint.
It is charging as it should now.
Thank you all for pointing me in the right direction!
 

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