6V Genny Now Overcharging

JCinKY

Member
Much obliged to those who helped me get the charging worked out, now I need a little help reigning it in.

Battery charged showing 6.4 volts. Ammeter shows +10 amps at 1/4 throttle and +20 at 3/4 throttle. Gen output is 8 volts at 1/4 throttle and over 10 volts at 3/4 throttle. Battery shows 8 plus volts at high throttle.

Read soundguys post from long ago and disconnect field at Gen, killed charge. Disconnected field at vr, same result. Bad vr or bad wiring? Don't wanna spend the $ on a new vreg or the time on new harness in the dark.

Disconnecting either field also helped it run better, odd. Its having trouble at high rpm, can't get to full throttle. Can't tell if rich or lean and adjustment helps slightly. Carb just cleaned, spotless.
 
try this.

make sur ethe field bias resistor under the reg is not shorted to case or touching chassis.

now disconnect field wire at genny and vreg.. bend the wires back.. use a jumper wire to make the connection.. this will rule out a bad wire in the harness.

if it still maxes out the charge.. field circuit is closed.. may even have welded contacts.

if vreg is old / non returnable.. pry the can off and see if the contacts are welded shut. many times you cn pop them apart and dress them.

if they are just staying closed but not welded, and no adjustment helps.. it will be time for a new vreg.

in an emergency, if you needed some charge, find a ignition resistor or light bulb ( turn signal may work ).. and wire it from ground to field on genny.. expirement to see what you get for charge rate. just unhook the wire at shutdown. if you have a 3 position switch, center off.. SPDT and 2 different resistors.. you could wire field to the center common post, and one other post thru large resistor to chassis, and other post thru small resistor to chassis. center is no charge.. with large resistor selected.. low charge.. with small resistor selected.. hi charge.

you just made a tickle switch.

post back
 
(quoted from post at 18:02:31 03/05/13) try this.

make sur ethe field bias resistor under the reg is not shorted to case or touching chassis.

now disconnect field wire at genny and vreg.. bend the wires back.. use a jumper wire to make the connection.. this will rule out a bad wire in the harness.

if it still maxes out the charge.. field circuit is closed.. may even have welded contacts.

if vreg is old / non returnable.. pry the can off and see if the contacts are welded shut. many times you cn pop them apart and dress them.

if they are just staying closed but not welded, and no adjustment helps.. it will be time for a new vreg.

in an emergency, if you needed some charge, find a ignition resistor or light bulb ( turn signal may work ).. and wire it from ground to field on genny.. expirement to see what you get for charge rate. just unhook the wire at shutdown. if you have a 3 position switch, center off.. SPDT and 2 different resistors.. you could wire field to the center common post, and one other post thru large resistor to chassis, and other post thru small resistor to chassis. center is no charge.. with large resistor selected.. low charge.. with small resistor selected.. hi charge.

you just made a tickle switch.

post back

'preciate all the good ideas. I'll get back on it tomorrow, ran out of dry wood to heat the shop.

The contacts weren't welded as of yesterday. VR is less than a year old with bolt on cap. Cleaned contacts when I was looking for charge. I'll have to make sure the resistor isn't grounded for sure. The rubber isolators looked in good nick so I think the case isn't grounded, but will have to double check with test light around mounting bolts.

I'll jump her tomorrow after work and let you know what I find.

Jeff
 
JC.......you write......."Battery charged showing 6.4 volts. Ammeter shows +10 amps at 1/4 throttle and +20 at 3/4 throttle. Gen output is 8 volts at 1/4 throttle and over 10 volts at 3/4 throttle. Battery shows 8 plus volts at high throttle" .........yep, them's NORMAL readings. Ittza LAW, Electro-chemical Laws.

You complain........"Its having trouble at high rpm, can't get to full throttle".......that's an IGNITION or CARBURETOR problem........NOT genny problem. ........sheesh, respectfully, Dell
 

" The rubber isolators looked in good nick so I think the case isn't grounded,"

WELL, IF IT IS NOT GROUNDED, then that is likely your problem!!!!
 
there's no reason your machine should be charging at 10v/20a for any length of time except for a few seconds after startup. if it continues doing that.. it's NOT normal.

initial high charge rate at startup is normal.. and it should taper off pretty quick.
 
(quoted from post at 18:42:14 03/05/13) i agree.. no ground reference or a floating / biased ground will for sure cause overcharging.

I guess I misunderstood or did not give thorough information. Gen is grounded to frame through the mount, ground stud is connected to vr case via harness to vr case.

The case is not bolted directly to chassis, via isolators. I took this to mean that I don't see how the vr resistor could be shorted to chassis ground unless the isolators were missing or broken down.

JMOR, I have used your front mount 6V diagram and referenced your pic from my other post. My vr did not have the oe tab, but the field circuit is connected to the case via the resistor. Thus grounded via harness and Gen ground?
 
(quoted from post at 22:43:54 03/05/13)
(quoted from post at 18:42:14 03/05/13) i agree.. no ground reference or a floating / biased ground will for sure cause overcharging.

I guess I misunderstood or did not give thorough information. Gen is grounded to frame through the mount, ground stud is connected to vr case via harness to vr case.

The case is not bolted directly to chassis, via isolators. I took this to mean that I don't see how the vr resistor could be shorted to chassis ground unless the isolators were missing or broken down.

JMOR, I have used your front mount 6V diagram and referenced your pic from my other post. My vr did not have the oe tab, but the field circuit is connected to the case via the resistor. Thus grounded via harness and Gen ground?
he VR case needs to be grounded. Maybe by a separate wire to generator case (that was Ford normal) & maybe to tractor chassis by a bolt, or perhaps both, but thee case must be grounded. Case is not grounded by way of a resistor.
 
After work I will jump gen field to vr field to make sure wiring is not shorted to ground. I will also add another ground from vr case to chassis, there is an empty bolt hole close by. I'll let you know what I find.
 
Well all, it seems I will not get to solve the charging situation.

The powers that be have saw fit to have my tired old piece of iron spin a bearing. Ahh...

Fired it up tonight for testing. Had 15 lbs op warm and started a loud groaning from the front of the engine. Pulled dipstick and found lots of babbit. Further diagnosis required by autopsy.
 
Time for a hydrometer check on the battery plus a good cleaning of battery posts and cable terminals.a battery with a shorted cell will cause the generator to over charge.Back when a new battery was 30.00 I kept a new one on hand for trouble shooting.Ive found some odd problems in batteries that were solved by trying a new battery.My last 6v battery gave problems because the center cell read half charge while the other two read full charge.I had a 12v battery that would start my truck ok on a zero morning and just crank very slow when restarted 10 miles away.Took a new battery to fix that.Ive had many battery failures in summer.
 
Welp, crank been turned and new rods and mains and she's back up on her feet. No 2 main bearing spun to what I suspect was low torque on the cap. Got about 20 lbs OP cold and 10 hot, so I may rebuild the pump next time (and I hope there is no next time) :?

Went ahead and put a new bearing and bushing in the genny while I was at it and she is much happier. By sanding a little around the Vreg I got a better ground and the problem was solved.

My ammeter reads about 20 amps after startup, but falls quickly to 0 with a fully charged battery. Now I need to get the lights back on.

If it dries out, I hope to have the garden plot turned by late this week. Big thanks to everyone who hung in there with me and helped out.

Jeff
 

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