Farmall h charging problem.

Cecil09

Member
Trying to get some help on my farmall H. Have read through pretty much all the post I can find regarding this but I’m just not too certain what is going on. When I bought it I was told it had a bad battery so I replaced it. It ran well for several months but the gauge never really showed that it was charging. So I went through and replaced all the wiring replaced the gauge and pretty much the same. When I pull the ignition switch before starting it the needle on the gauge will vary slightly tip to the discharge side and once I start it it goes back to zero. But it will never charge while running it. It never stalls out but for the first time since I got it it would not start up again after I turned it off until I jumpstarted it. I ran through that checklist that John had posted on here but I’m still kind of confused. If I measure the voltage off the bat terminal of the generator it reads 7.2 V. But if I check voltage on the battery it’s only ever 6.11 V. I’ve gone through checked all my connections and I ran a ground wire from the four. Switch just to make sure it was getting a good ground. Does anybody have any suggestions on what to try? It appears to me that the generator is trying to charge but it’s never getting to the battery.
 
Cecil, you state " If I measure the voltage off the bat terminal of the generator it reads 7.2 V. But if I check voltage on the battery it’s only ever 6.11 V."

What happens if when running you jump the gennys FLD post to ground??? If it charges then (battery voltage rises) but NOT otherwise the VR isnt well grounded (if its a VR system) or the VR is bad (if a VR system). If its a cutout relay with a LHDB light switch system, the light switch isn't well grounded or the wires bad up to it......

Actually its the BAT terminal on the Voltage Regulator (or a cutout relay) that gets to the battery to charge it via the series ammeter AND THOSE TWO SHOULD BE NEAR THE SAME VOLTAGE. The output voltage of the GENERATOR is its ARM terminal which wires to the VR's ARM/GEN terminal and then once a good cutout relay is closed it gets to the battery via the BAT terminal and ammeter as I just described.

If the voltage on the VR's BAT terminal isn't getting transmitted to the battery there could be an ammeter or a wiring problem. Try a jumper wire from the VR's BAT direct up to the battery (that by passes the ammeter and wiring) and when running see if battery voltage rises then???? if so the ammeter or wiring may be bad. On some tractors the wire (NOT one from BAT on VR the other one) from the ammeter gets to the battery via a wire to the starter solenoid or switch where the big battery cable attaches INSURE ALL THAT WIRING IS IN PLACE or else the genny cant charge the battery.

John T
 
(quoted from post at 08:26:36 10/23/17) Cecil, you state " If I measure the voltage off the bat terminal of the generator it reads 7.2 V. But if I check voltage on the battery it’s only ever 6.11 V."

What happens if when running you jump the gennys FLD post to ground??? If it charges then (battery voltage rises) but NOT otherwise the VR isnt well grounded (if its a VR system) or the VR is bad (if a VR system). If its a cutout relay with a LHDB light switch system, the light switch isn't well grounded or the wires bad up to it......

Actually its the BAT terminal on the Voltage Regulator (or a cutout relay) that gets to the battery to charge it via the series ammeter AND THOSE TWO SHOULD BE NEAR THE SAME VOLTAGE. The output voltage of the GENERATOR is its ARM terminal which wires to the VR's ARM/GEN terminal and then once a good cutout relay is closed it gets to the battery via the BAT terminal and ammeter as I just described.

If the voltage on the VR's BAT terminal isn't getting transmitted to the battery there could be an ammeter or a wiring problem. Try a jumper wire from the VR's BAT direct up to the battery (that by passes the ammeter and wiring) and when running see if battery voltage rises then???? if so the ammeter or wiring may be bad. On some tractors the wire (NOT one from BAT on VR the other one) from the ammeter gets to the battery via a wire to the starter solenoid or switch where the big battery cable attaches INSURE ALL THAT WIRING IS IN PLACE or else the genny cant charge the battery.

John T


Sounds good John. It is a cut out relay. Not VR. I’ll try grounding the field post and see if that helps. Then I’ll run a jumper from bat terminal to the battery. See if that changes anything. I’ll get back to you hopefully tomorrow. Tractor is not at my house and I work all day today and tomorrow.
 
If the generator wasn’t properly grounded will I still be getting a voltage reading off the bat terminal of the cut out relay? I know a lot of the components were recently painted but I’m not sure if the contact points for sanded afterwards. I know it’s not that difficult to pull off and check But I was just curious
 
The bat terminal on the cutout is connected to the battery all the time (through the amp meter) thus it will have voltage there.
The regulator body can be grounded to the mounting point (or engine) with a 12gauge jumper wire and some terminals, Drill a screw
hole in the base (careful to not hit anything when the drill goes through) and attach the grounding wire. Attach the other end to a
clean shiny place on the block. Jim
 
John, I tried what you said. I ran a jumper from the cutouts bat terminal to the battery in the voltage did not increase. I tried grounding the field post directly to frame and the battery voltage did not increase. I took the generator off and sanded all contact points on the mount, generator, and block. The voltage coming out of the bat terminal on the cut out ranges from 7 to 7.3. Not sure what’s going on here it doesn’t really make sense to me. I just don’t understand how I can have 7.3 V coming out of the generator and it not charge the battery.
 
The cutout is bad, causing disconnect from the battery. testing the output by grounding the field proves the gen. and condemns the
cutout. Jim
 
(quoted from post at 19:13:27 10/24/17) The cutout is bad, causing disconnect from the battery. testing the output by grounding the field proves the gen. and condemns the
cutout. Jim
I apologize for really not understanding how this whole generator thing works. The thing I don’t understand is if the cut out is bad and not communicating with the battery, how is it producing 7.3 V at the bat terminal of the cut out?
 
(quoted from post at 08:25:31 10/26/17) I apologize for really not understanding how this whole generator thing works. The thing I don’t understand is if the cut out is bad and not communicating with the battery, how is it producing 7.3 V at the bat terminal of the cut out?
Yeah, I have been following this thread and wondered about the same thing. Are you saying the battery voltage reads 6.11 WHILE THE ENGINE IS RUNNING and the voltage at the cut-out BAT terminal (not GEN terminal) is 7.2? If so, the problem isn't the cut-out.

Take additional voltage readings at various places in the circuit from the cut-out BAT terminal to the battery post (each side of ammeter, starter switch etc.). Somewhere you will find the voltage drop and the root of the problem.
 
(quoted from post at 08:52:45 10/26/17)
(quoted from post at 08:25:31 10/26/17) I apologize for really not understanding how this whole generator thing works. The thing I don’t understand is if the cut out is bad and not communicating with the battery, how is it producing 7.3 V at the bat terminal of the cut out?
Yeah, I have been following this thread and wondered about the same thing. Are you saying the battery voltage reads 6.11 WHILE THE ENGINE IS RUNNING and the voltage at the cut-out BAT terminal (not GEN terminal) is 7.2? If so, the problem isn't the cut-out.

Take additional voltage readings at various places in the circuit from the cut-out BAT terminal to the battery post (each side of ammeter, starter switch etc.). Somewhere you will find the voltage drop and the root of the problem.

Yes. The battery read 6.11 and drops while it is running. The bat terminal on the cut out reads anywhere from 7 to 7.3V while the engine is running at about half to 3/4 throttle. I will trace all of the wires and do voltage readings this weekend. Thanks for the help so far
 
OK so I got out there today and a little more work. I was able to get it to charge after I ran a ground wire from the cut out housing then dead grounded the F terminal. I ran an independent ground wire from the switch but it’s still not Charging without the dead ground to the F terminal. So I’m assuming that either the ground on the switch is bad for I have a bad switch. Is there a problem just keeping the dead ground to the F terminal? If it’s a bad switch I really don’t want to replace it because I will most likely be putting a 12v alternator on it next year And getting a new three position switch
 
The dead ground on the F terminal of the generator puts it permanently in HIGH charge, the same you should get with the light switch set on "H". If you don't run the tractor a lot, it can stay that way. If you are using the tractor a lot, as in take it out and run it all day, you can connect the generator F to the cut-out F (without grounding the F terminal) and get the LOW charge rate. This would be the same as running with the light switch set to "L".
 
Get the appropriate regulator intended to replace the cut-out on whatever generator you have. Hook it up as I already described for LOW charge.
 
Cleaned up the ground that I ran from the light/charging switch and she charges as she supposed to. However now I think I have some battery drain. What’s the best way to track this down? I’m going back out later to see if she’ll still start. How do I know if the cut out is sticking open?
 
You mean sticking closed? You will be able to measure voltage on the GEN terminal when the engine is not running.
 
(quoted from post at 11:31:02 10/29/17) You mean sticking closed? You will be able to measure voltage on the GEN terminal when the engine is not running.

Yeah. That’s what I meant. Thanks Jim
 
(quoted from post at 11:31:02 10/29/17) You mean sticking closed? You will be able to measure voltage on the GEN terminal when the engine is not running.

Checked voltage on the gen post of the cutout and it was the same as battery. Gave it a tap with the palm of my hand and it dropped to 0. We will see if that fixed it. Hopefully it did. I have it charging now. Thanks for your help guys.
 
Unhook the battery and take the cover off the cut-out. Go in with a point file and lightly file the contacts (they should be open!). Don't use any type of paper abrasive, just the point file. Likely as not, they are sticking because somebody was already in there with emery cloth. You might give them a quick shot of contact cleaner or brake cleaner too. Be careful not to bend anything! Close it back up and hope for the best.
 
(quoted from post at 15:32:28 10/29/17) Unhook the battery and take the cover off the cut-out. Go in with a point file and lightly file the contacts (they should be open!). Don't use any type of paper abrasive, just the point file. Likely as not, they are sticking because somebody was already in there with emery cloth. You might give them a quick shot of contact cleaner or brake cleaner too. Be careful not to bend anything! Close it back up and hope for the best.

thanks.
 

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