Generator intermittently overcharging

[jerseyjeep2003]

My 71 M35 started overcharging the other night. I hadn't noticed the gauge, but sure did hear the belts screaming, after turning the power off and on a couple of times all was OK. I had the batteries load tested, one was good and the other marginal. I then had then generator spin tested at Torodyne (great guys), they said no problems that they could see. So I replaced all of my cables and both batteries......still bounces between 28.2V and 35V when checked at the batteries. It seems to be the worst when the truck is fully warmed up. Any ideas? Voltage regulator going south after it heats up? I'm about ready to just pop for a 24 v new style alternator and be done with it. Just hoping that I didn't miss something and then fry a new alternator too. Oh, I have also replaced the starter with a new gear reduction starter and relay, and new push button start switch. So pretty much everything in the start/charge circuit has been replaced. Thanx for the input.

 

[steelandcanvas]

Did you tweak the voltage adjustment under the hex plug on the generator? Take a small screwdriver and twist it back and forth a few times, then set your voltage with a meter at 28.25 volts, with the motor running. That should put you on the notch on the voltmeter in the truck. This may help, and then again may not. Here is a link to a new regulator, should you need to go in that direction:
http://eriksmilitarysurplus.com/reasforam60a.html

 

[panshark]

sounds fishy for the voltage to be jumping that much when you're testing at the batteries. 35v might be max charge for that generator. This may be a really, really dumb question, but it needs to be asked: does your truck use a generator or an alternator? My '72 came with an alternator (internal voltage regulator, located in the back of assembly) but if your's is a generator the voltage regulator may be located...somewhere's above the steering column, on the firewall. A free shot at repair might be to trace wires to starter, battery bank and alternator, maybe look for a short.

Quality of your multimeter might factor into your data. Just sayin...if you got a 99 cent special, throw it away and get a real tool.

My belts started squeaking, and my charging system started way overcharging when I had a battery connection come loose on a road trip. DogHead correctly diagnosed a fried internal voltage regulator.

There should be a continuous variation of voltage being supplied by the alternator, due to its design (i.e. off/on/off/on) but 28.2-35 sounds wrong. So back to the first question: are you using an alternator or generator?

 

[jerseyjeep2003]

sounds fishy for the voltage to be jumping that much when you're testing at the batteries. 35v might be max charge for that generator. This may be a really, really dumb question, but it needs to be asked: does your truck use a generator or an alternator? My '72 came with an alternator (internal voltage regulator, located in the back of assembly) but if your's is a generator the voltage regulator may be located...somewhere's above the steering column, on the firewall. A free shot at repair might be to trace wires to starter, battery bank and alternator, maybe look for a short.

Quality of your multimeter might factor into your data. Just sayin...if you got a 99 cent special, throw it away and get a real tool.

My belts started squeaking, and my charging system started way overcharging when I had a battery connection come loose on a road trip. DogHead correctly diagnosed a fried internal voltage regulator.

There should be a continuous variation of voltage being supplied by the alternator, due to its design (i.e. off/on/off/on) but 28.2-35 sounds wrong. So back to the first question: are you using an alternator or generator?

It has the "newer" style generator with an internal regulator. Everything has been replaced in the starting/charging system. My first suspect was the cables as they were loose in the crimp on ends. But, new cables, terminals and batteries didn't help. It just seems funny that it seems to be OK when the system is cold, but once it starts to charge and heat up is when it jumps around. My test meter isn't a Harbor Freight special, but, it didn't cost a fortune either ($39.95) The belts do scream when the gauge pegs out OVER the red zone. Got a price of $150 on a new modern style alternator (one wire hook up). Not too bad, since it would cost me half that much just to replace the old regulator. IF I go that route I will have to fab up a mount, but that's no biggie since I work as a machinist and have everything including welders at my disposal.

 

[jerseyjeep2003]

Did you tweak the voltage adjustment under the hex plug on the generator? Take a small screwdriver and twist it back and forth a few times, then set your voltage with a meter at 28.25 volts, with the motor running. That should put you on the notch on the voltmeter in the truck. This may help, and then again may not. Here is a link to a new regulator, should you need to go in that direction:
Regulator Assembly For AMA5104UT 60 Amp 24 Volt Alternator, AMA2004AS

I haven't tried adjusting it, but, it is worth a shot when I get up today.

 

[AGE|kshaufl]

I'm going to have to agree with Steelandcanvas. Sounds to me like a voltage regulator is getting ready to go. I would follow the instructions on adjustments to it. The only thing that I would say to do is turn the screw once each way with the engine off. Then start the engine and adjust it as the instructions say. The extra step might help with a better contact on the rheostat. The rheostats, which are analog, are the weak link here. A good example of this are the old radios that when you turn the volume nob you get static and pop until it is moved a few times back and forth, then you get good clean music.

 

[jerseyjeep2003]

No luck with adjusting, if anything it got worse. After taking note of it's original position I turned it back and forth a couple of times, then set it back to where I started and slowly turned it up and down. It started out at 34.2 volts and only moved a volt in either direction. Even though the gauge doesn't have actual number readings, I considered the white line in the green area as normal (28 v) and used my test meter against that, so 3/4 through the red is reading 34.2 v on my digital meter. I guess I will head over to see the guys at Torodyne (shameless plug), and get the alternator. I am just tired of dealing with it, but more than that... I WANT TO DRIVE MY TRUCK AGAIN.....it's been almost three weeks..lol. I'll take some pics of the mount fabbing and the install for y'all.

 

[steelandcanvas]

You can always throw that regulator assembly in your alternator from Erik's (another shameless plug). Sorry the "tweaking trick" didn't work. Good luck, whatever you do. Get her back on the road!

 

[panshark]

when I was having trouble with my alternator, I disconnected the wires and drove the truck anyway. I was limited to daytime driving, but it would take me a while to need to recharge the batteries. I only used the batteries to start the truck and operate the brakes/signals. Depending on your driving habits, you may just drive it anyway.

 

[jwaller]

if you must drive the truck then crack it off the batteries and then just shut off the acc switch. it will continue to run and drive normally. you just won't have some of the gauges on the dash.

 

[panshark]

Jwaller is right on, my previous post was incomplete. You can periodically flip on the accessory switch to check your gauges.

 

[jerseyjeep2003]

That is exactly what I did, but, being as anal as I am, I wasn't content with that. Flipping the switch off works great and saved the batteries from being burnt toast. I picked up the new alternator, so, tonight I will modify the existing bracket and do the install tomorrow.

 

[OPCOM]

The newer generator (60A model) has a safety feature that burns out a resistor when the volts go too high. A god video about the generator:
[media]http://bunkerofdoom.com/travel/steelsoldiers4/20080929_memphis/100_7052.mov[/media]
or
bunkerofdoom DOT com/travel/steelsoldiers4/20080929_memphis/100_7052 DOT mov


pics:
Untitled Normal Page

per memphis.

 

[panshark]

please post pics of your fab job. I ended up making a new bracket out of angle iron because I didn't want to modify the original bracket and not have it work right.

 

[jerseyjeep2003]

please post pics of your fab job. I ended up making a new bracket out of angle iron because I didn't want to modify the original bracket and not have it work right.

Yeah, I tried to modify the original.....didn't work out so well. The holes for the pivot point wouldn't allow the "ears" of the pivot point on the new alt to clear the bracket. So on to plan B, I got a couple pieces of flat stock and bent 90 degree angles on them to make the pivot, will weld them together to make the bracket, then drill the 3 holes to mount to the block. I am going to countersink them so I can use flat head socket screws (nylocks) for a flush mount. I will also have to make the slide adjustment bracket since the new alt uses all 1/2" bolts. I may also have to space the bracket out from the block a little to allow clearance for the lower radiator hose. I'll post up some pics of the finished bracket mounted and unmounted.

 

[usmcm35a2]

bad regulator

It has the "newer" style generator with an internal regulator. Everything has been replaced in the starting/charging system. My first suspect was the cables as they were loose in the crimp on ends. But, new cables, terminals and batteries didn't help. It just seems funny that it seems to be OK when the system is cold, but once it starts to charge and heat up is when it jumps around. My test meter isn't a Harbor Freight special, but, it didn't cost a fortune either ($39.95) The belts do scream when the gauge pegs out OVER the red zone. Got a price of $150 on a new modern style alternator (one wire hook up). Not too bad, since it would cost me half that much just to replace the old regulator. IF I go that route I will have to fab up a mount, but that's no biggie since I work as a machinist and have everything including welders at my disposal.

Mine did the same thing, cold fine, drive it 3-4 miles and it would peg the needle in the red and belts start to scream. This was a new regulator after the first one died. Ended up replacing the 2nd regulator with another new one and works just fine. Alternator repair shop refunded the money on their bad one, got a new one online for 1/2 the cost and works great.

 

[jerseyjeep2003]

Pictures as promised. It wasn't too bad getting it in place, but, I probably should have moved the fuel filter housing out of the way since I have big hands and could have used a little more room. I used standard Dayco 47" belts. But, all done and charging at 27.8 volts with everything on. Going to take it out and get my dinner since my wife is out with some friends. I can get a few more pics tomorrow if anybody wants to see a different angle.

I may even make some of these up for sale if there is interest

 

[jerseyjeep2003]

Pictures as promised

Pictures as promised. It wasn't too bad getting it in place, but, I probably should have moved the fuel filter housing out of the way since I have big hands and could have used a little more room. I used standard Dayco 47" belts. But, all done and charging at 27.8 volts with everything on. Going to take it out and get my dinner since my wife is out with some friends. I can get a few more pics tomorrow if anybody wants to see a different angle.

I may even make some of these up for sale if there is interest

 

[jerseyjeep2003]

OK, maybe they will go up this time.

 

[Dieselking22]

Dang those are really nice! great job!