ford 800 voltage regulator

jollymon · Oct 27, 2014

Last week I posted about a charging problem
after replacing the voltage regulator which
failed after a couple days. I now have a new
VR. Looking at both of the failed VR's it
looks like they are getting very hot. The
spring on the BAT side is black on both with
melted plastic. After puting in the new vr's
the amp meter was always showing a maximum
charge (30 amp) without ever dropping. I hate
to put in another one and have the same thing
happen. Is the constant charging causing the vr
to overheat and fail or did the vr fail to
operate properly? Are there other possible
causes for this other than a failed VR? Thanks

JMOR · Oct 27, 2014

(quoted from post at 11:44:23 10/27/14) Last week I posted about a charging problem
after replacing the voltage regulator which
failed after a couple days. I now have a new
VR. Looking at both of the failed VR's it
looks like they are getting very hot. The
spring on the BAT side is black on both with
melted plastic. After puting in the new vr's
the amp meter was always showing a maximum
charge (30 amp) without ever dropping. I hate
to put in another one and have the same thing
happen. Is the constant charging causing the vr
to overheat and fail or did the vr fail to
operate properly? Are there other possible
causes for this other than a failed VR? Thanks

laborate on "spring' and "plastic", please. Not by any chance calling this resistor a spring?

jollymon · Oct 27, 2014

I think I should have said copper wire coil on the BAT side it burnt black. On the new VR it is bright copper. On top of the coil black plastic it oozing out of the top portion of the coil. The contacts no longer move.

JMOR · Oct 27, 2014

(quoted from post at 12:45:49 10/27/14) I think I should have said copper wire coil on the BAT side it burnt black. On the new VR it is bright copper. On top of the coil black plastic it oozing out of the top portion of the coil. The contacts no longer move.

K, I think I have it. The heavy outside wire surrounding the cut out coil. That is the current sensing coil & it sounds like it has seen more than its rated 20 amperes. Normally, unless something is mis-wired or otherwise wrong with generator, the current through this winding is generator output current (20 amperes, I believe on your tractor) and the reverse current when generator output falls below battery voltage, at which point it serves to open the cut out and halt reverse current flow from battery into the generator. If this fails to happen (perhaps with stuck cut out contacts or other VR failure), then the current can go very high (perhaps 60+ amperes) and this winding, the generator, and/or wiring may burn up.

jollymon · Oct 27, 2014

Thanks for the info. I would say both have burned out the same way. I am assuming everything is wired correctly.
I will check the field and ground wire coming off generator to make sure they are not crossed. Other than a bad VR any ideas on what could cause the amp meter to stay at maximum charge?

JMOR · Oct 27, 2014

(quoted from post at 13:26:48 10/27/14) Thanks for the info. I would say both have burned out the same way. I am assuming everything is wired correctly.
I will check the field and ground wire coming off generator to make sure they are not crossed. Other than a bad VR any ideas on what could cause the amp meter to stay at maximum charge?

ssuming good ammeter, an internal generator problem shorting the Field terminal/coil would also yield full output at all times, just like VR field contacts being closed. I would fully expect that the burning that you see is reverse current rather that max charge all the time, as rev current can be many times the charging current. That comes from cut out not opening upon shut down, which you should see as a major full scale discharge on ammeter after engine shut down & a very hot generator over the following minutes and if you remove battery cable under these conditions, you should observe sparking upon disconnect & reconnect. If your observed burning of the current winding on cut out is a result of too high current through this winding, then, you should see same burning on current winding of the field control relay, as it is the same heavy wire on both connecting BATT to ARM via cut out contacts.

jollymon · Oct 27, 2014

Thanks again. I do not think I was getting a discharge at shut down. I will put it back together and check. I do not really understand how the whole system works. What I find really confusing is that the three wires coming off the generator all show conductivity with ground. How could the field wire be shorting when there is already conductivity?

JMOR · Oct 27, 2014

(quoted from post at 13:52:39 10/27/14) Thanks again. I do not think I was getting a discharge at shut down. I will put it back together and check. I do not really understand how the whole system works. What I find really confusing is that the three wires coming off the generator all show conductivity with ground. How could the field wire be shorting when there is already conductivity?

What I find really confusing is that the three wires coming off the generator all show conductivity with ground." Because in idle state, all there terminals find their way to ground. The Gnd post, by virtue of simply being a screw into the barrel of the generator, the ARM terminal by a path through the armature brush, armature windings & the second brush to the generator case (barrel), and finally, the Field terminal by a path through the field windings to the barrel. "Continuity" is the word that is getting you. It does[u:5396c13626] not[/u:5396c13626] mean that whenever you measure continuity that it is as if you were measuring across a copper penny. You still have continuity even measuring across a cup of salty water or from your sweaty thumb to index finger. Different degrees, but still continuity.

JMOR · Oct 27, 2014

jollymon, if you are worried about toasting yet another VR, do this: Disconnect & tape Field & Arm wires at generator. Start engine & connect jumper from generator ARM terminal to wire on BATT terminal of VR (go ahead & take that wire off of the VR BATT terminal ). Speed up engine & look at ammeter (probably won't show charge, probably discharge. Let me know. Now with all else the same, connect a jumper from the generator Field to Generator ARM terminal. Should show full charge. Remove Field jumper. Stop engine, being ready to remove ARM to BATT jumper as soon as you look at ammeter after shut down. Should be showing big discharge. NOW REMOVE THAT JUMPER. Come back with your observations.

jollymon · Nov 1, 2014

Jmor, Thanks again for your help. Murphy came visiting and I just now got back to the tractor. The test did just as you said showing a discharge with a jumper from generator ARM to BATT wire from VR. Then a charge with generator ARM to generator FLD. I removed FLD jumper, stopped engine and ammeter showed big discharge. Hopefully this is what should happen.

JMOR · Nov 1, 2014

(quoted from post at 10:34:59 11/01/14) Jmor, Thanks again for your help. Murphy came visiting and I just now got back to the tractor. The test did just as you said showing a discharge with a jumper from generator ARM to BATT wire from VR. Then a charge with generator ARM to generator FLD. I removed FLD jumper, stopped engine and ammeter showed big discharge. Hopefully this is what should happen.

es, that is what should happen. I would call the generator good. Now, correct wiring & a good VR and all should be well. Always be sure VR case has good connection to generator ground. By the way, with what you have just completed, your generator IS polarized & nothing further is needed as regards polarization.

jollymon · Nov 1, 2014

Thanks again. I hope it works.

jollymon · Nov 3, 2014

I am sorry to report that the VR has fried again. When first started the ammeter bounces from 20-30 for about 5-10min. Then the ammeter maxes out. After 30 min the ammeter was at 0. At this point I assumed the vr was dead. I pulled the cover off. The copper coil is again black just like the other two. It does not seem possible that I have recieved two bad VR's. Any more ideas on what is causing this.

JMOR · Nov 3, 2014

(quoted from post at 13:56:55 11/03/14) I am sorry to report that the VR has fried again. When first started the ammeter bounces from 20-30 for about 5-10min. Then the ammeter maxes out. After 30 min the ammeter was at 0. At this point I assumed the vr was dead. I pulled the cover off. The copper coil is again black just like the other two. It does not seem possible that I have recieved two bad VR's. Any more ideas on what is causing this.

ell, I do have at least one more idea. What if it has a 12v generator hanging on it & you are trying to make it play with a 6v battery & 6v VR?? Did you ever have a working charging system on this tractor? Measure Ohms from one barrel terminal of generator to the other (Field to Ground) (no wires attached).. See about 3 Ohms or about 7 Ohms?

jollymon · Nov 4, 2014

Removed field and ground wire from generator. Tested between poles which showed 3 - 3.5 ohms. The generator was rebuilt about 2 years ago. Worked fine until the VR burnt out about a month ago. The generator showed about a 7.5v output when last tested. I tested the ground connection for the VR case and it seemed fine. Could a short in the ground or other wire cause the VR to burnout? Thanks again for your help.

JMOR · Nov 4, 2014

(quoted from post at 14:10:55 11/04/14) Removed field and ground wire from generator. Tested between poles which showed 3 - 3.5 ohms. The generator was rebuilt about 2 years ago. Worked fine until the VR burnt out about a month ago. The generator showed about a 7.5v output when last tested. I tested the ground connection for the VR case and it seemed fine. Could a short in the ground or other wire cause the VR to burnout? Thanks again for your help.

o 'short in ground'...if insulation on ground wire rubbed thru & wire touched the chassis, both were & still would be ground....no problem. The generator output capacity should not be capable of burning up the large current coil windings. The only way current should be able to reach such heights would be at shut down & only if & when the cut out fails to open, thus allowing the battery to discharge back thru the VR and the generator. Makes for a hot to the touch generator & usually a dead battery. Doesn't sound like this last one lasted long enough to make it to shut down....correct? What brand VRs are these?

jollymon · Nov 4, 2014

It looks like it failed during operation. It was showing a high charge then dropped to nothing after about 30 min. I got the VR from Yesterdays Tractor. They sent me a replacement for the first failure which also failed. Everything is pointing to another bad VR. How many will they replace? Not sure what else to do. Tractor Supply has one for $50. Tractor operation at $50/half hour. Ouch.

JMOR · Nov 4, 2014

(quoted from post at 14:53:21 11/04/14) It looks like it failed during operation. It was showing a high charge then dropped to nothing after about 30 min. I got the VR from Yesterdays Tractor. They sent me a replacement for the first failure which also failed. Everything is pointing to another bad VR. How many will they replace? Not sure what else to do. Tractor Supply has one for $50. Tractor operation at $50/half hour. Ouch.

Is the battery good? Will it hold a charge & start up after a day or two? Probably just crappy VRs, given all the other tests/observations/checks that we have made.

jollymon · Nov 4, 2014

Battery is fairly new. It has been holding a charge for months without use.

JMOR · Nov 4, 2014

(quoted from post at 16:01:49 11/04/14) Battery is fairly new. It has been holding a charge for months without use.

ell, sir, since it apparently only saw charging (forward current) from the generator to battery & never (reverse current) from battery to generator, I guess I'll have to go with the fault being 'Cheap-Chinee', as a decent VR should handle fully generator output all day long. "Maybe" NAPA has an American made or some better quality, but I do not know.

ford 800 voltage regulator

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