M38a1 is over charging its batteries

Post by **wesk** » Mon Jun 23, 2008 12:47 am

Hello Rich,
I get the feeling you are not quite up to tackling this in depth adjusting regimen or you are becoming tired of the intricate maneuvering that must be accomplished. There is certainly not enough room here to conduct an in depth DC electrical systems orientation. At any rate I must emphasize the importance of using the correct terminology consistently in this subject area to avoid serious errors. You have three components on the regulator that are adjustable. The circuit breaker is adjusted to open at a certain voltage and close at a certain voltage. This unit is independent of the other two components. You have a current regulator that is adjustable to a maximum allowable current value. This adjustment requires an amp meter capable of measuring 25 to 30 amps. Most small Fluke VOM's can only handle several milliamps. There are rather expensive range expanders available for them. The carbon pile rheostat or lamp load set are tools used to apply a load of a known value to the system. These are needed both to set the maximum allowable amperage flow through the current regulator and to assist with the adjusting of the third component of the regulator which is the voltage regulator unit.

[quote]
1-Are both the voltage and ammeter armature screws adjusted back and forth until satisfactory readings are obtained?

The voltage regulator and current regulator armature spring screws are adjusted when an adjustment is called for by the readings you observe when that unit is being tested. You loosen the lock nut if present and turn the shaft.

2-If the voltage screw is adjusted, then does the ammeter armature have to retested and readjusted in turn?

Yes sometimes.

3-What is a carbon pile load rheostat or lamp bank? (I thought a rheostat was used to adjust voltage supply to equipment, IE motor)

They are a tool that will provide an artificial load on the system.

4-How is the current adjusted to half by changing the load rheostat or lamp bank?

Actually a simple resistance adjusting rheostat is used to increase or decrease the field signal which in turn will increase or decrease the current flow from the generator. We use this to adjust the current flow to 1/2 of the system's normal capacity of 25 amps or 12.5 amps. Then we adjust system voltage to 28.0 while the system is operating in the middle of it's range.

5-How are the current readings taken with a standard fluke multimeter, instead of the military multi connection meter set?

By inserting the amp meter (capable of at least 25 amps) in series with the wire #4.

6-Is this process supposed to be done with the engine running the whole time, and no batteries connected?

No. The engine is running with batteries connected for the majority of tests. The engine is off or the battery disconnected during adjustments.

7-Is the test cable supposed to be plugged in between the regulator and the jeep harness?

Yes they are. You must have a means to interrupt the cable connections. Most of us use the adapter test lead sets provided by the Army. These facilitate opening a circuit and/or accessing a test point.

8-Can needle nose pliers be used to adjust the nut? It seems that this nut just loosens or tightens the contact spring. How can this adjust the voltage?

The armature spring tension determines when the contacts will open or close. These contacts are constantly and very rapidly opening and closing during system operation. The tool you select should not cause damage to anything.

[/quote

Test lead adapter kit.

RichJohnson · Post by **RichJohnson** » Mon Jun 23, 2008 7:35 am

I would really like to try this but am short some tools. I already checked with a few MV buddies and they dont have the loading tool either. What kind of place would I purchase this at?

I hate to by pass all this stuff, but is it possible to adjust the voltage armeture screw and then just test the volatge supplied to the batteries?
Lowering the overall voltage is what I am trying to accomplish. Would it be ok to just start there and see if it works, or will an adjustment of that much affect the current regulator setting adversly and open a can of worms that I wouldnt be prepared to deal with without the euipment.

Post by **wesk** » Mon Jun 23, 2008 8:27 am

Yes,
You can try to tweek the voltage regulator component only. Loosening tension on the spring about one turn and then recheck charging voltage at 2500 to 3000 RPM. This will be about the equivalent of 35 MPH in 3rd gear. Make very small adjustments and recheck each time.

Again I caution you not to have the cover off or attempt to remove or install it with batteries connected.

RichJohnson · Post by **RichJohnson** » Mon Jun 23, 2008 4:29 pm

Ok Wes. I have called around to auto shops and nobody knows what a carbon pile reostate is, let alone where to get one.

I checked with an auto electric shop that rebuilt my starter on my old m38 years ago that does old cars. They told me that they dont have that load either and they adjust regulators by feel untill they get the appropriate readings. More or less the way I was asking about. He did mention to go real slow if I tried it, half turn at a time or so.

Yes I see what you mean about taking the cover off while powered up, there is a burn mark inside the cover from somebody else.

I may try this technique and see what my results are, I dont think it can get any worse for me. At worst I would have to buy antoher one, but I have a 60 amp alternator upgrade kit for my m37 and once I do that job I will have the generator regulator left over and can use it in the jeep if necessary.

I will let you know how this goes soon.

RichJohnson · Post by **RichJohnson** » Mon Jun 23, 2008 8:52 pm

Ok well, I slowly made many adjustments to the voltage regulator contactor spring untill I got an average of 27 to 29 volts over a range of rpms.
Unfortunately, what I feared happening, happend. The ammeter now bounces back and forth from discharge to charge. It looks kinda like it spends more time on discharge.
Do I now need to adjust the current regulator spring tighter to increase current to the system to compensate?

What is your opinion?

It seems that nobody really knows exactly how to adjust these things any more and nobody has the equipment to test them properly. Electric shops just wing it I guess.
After calling several MV dealers, for pricing on replacments, most refered me to the transistorised unit for about 150 bucks.

Post by **wesk** » Mon Jun 23, 2008 10:41 pm

It seems that nobody really knows exactly how to adjust these things any more and nobody has the equipment to test them properly.

Well actually I do know how to properly adjust them and I do have the right tools.

I also know several other folks that can and do.

Most auto-electric shops make their serious money today by rebuilding 100's of simple modern units. It's not that they can't handle the ancient technology in these units, it's the time it takes from the mass production efforts that stops them from being helpful.

It is always best to take both the regulator and the generator to an experienced auto-electric technician and let them set the pair up on the test bench. Once properly set-up on the bench you will only have to polarize it when you install it in the jeep and start driving.

Many times these folks are retired and have a small shop at home where they putz with these units. Try to locate a few MVPA members in your area with several WWII vintage trucks. These older military regulators are very similar and the folks they get to work on theirs can handle yours.

The transistorized regulators are ok. There are no manuals for them and no parts. So each $150 unit is a throwaway when it gets out of adjustment or breaks down.

Do you have a copy of the 2005 MVPA membership directory? There are 16 members listed on San Diego. There are 3 affiliate clubs in CA: Inland Empire at Rialto 909-350-0548, MVC of Cal. San Jose 408-238-8277 and South. Cal. MVCC Hesperia 626-319-3542. I would bet a call to one of them would locate the repair facility you need.

RichJohnson · Post by **RichJohnson** » Mon Jun 23, 2008 11:18 pm

I am a member of both So Cal and San Diego chapters. The MVCC is Nor Cal.
I know all the SD members well, I dont think they can do the job.

I didnt insinuate that you couldnt do the adjustments or that other hobbyisis couldnt. I assumed that you can based on your experience and help on the boards over the years.

I was referring to shops and supply places that didnt know how to make the adjustments or what the equipement was.

So about the current regulator.
Should I try to adjust the current reguator spring tighter to increase the current?

Post by **wesk** » Tue Jun 24, 2008 8:42 am

You are now facing a sensitivity issue with the current flow rapidly starting and quitting. These two adjustments (volt regulator/current regulator) are interdependent and were meant to be adjusted together in very small increments. Right now you have current chasing voltage and then voltage chasing current. Any attempts made at adjusting now will be shots in the dark but you may get lucky.

In my previous post I was not directing you to other MVCC members for fixing your problem. I was pointing you towards them to ask them who is the technician they use to repair their WWII 6 and 12 volt regulators. There aren't any transistorized regulators for them to fall back on so they must fix what they have. Many of those members were ex-USMC and may have time at the Barstow depot where these items were stocked. I would not rule any of them out simply because I believed none were capable of fixing the regulator. I have 4 people within 50 miles of me here in Wisconsin's north country that still work on these so called outdated units. These same style DC electrical systems are still in use on modern turboprop aircraft where the starter and generator are combined into one unit.

RichJohnson · Post by **RichJohnson** » Tue Jun 24, 2008 8:11 pm

Well....I blew it.
The guy that owns the elec shop I used in the past suggested I try holding the contacts down on the current regulator. I was able to get better reaction from the current reguator on the ammeter from one adjustment but before I went further, tried what he suggested. That really didnt do anything I could tell, but I dropped the tool on the circut breaker and it stuck down. It had been reapidly moving up and down and now it was stuck. I tapped it to try and release it but then things inside the regulator started to smoke. The only insulated thing I had on hand was a pen in my pocket so I pried it up with my pen. I bent one of the copper contact arms on the circut breaker.

Is there any hope for me, or is it now trash.

Post by **wesk** » Tue Jun 24, 2008 10:07 pm

You have a 50/50 chance it's trash or just cooked some lacquer off a few turns of coil. A lot depends on what you can do with the current regulator damage. Maybe the best move here is to throw the regulator and generator in a box and copy the manual pages I've loaded and take it all to that shop and see if he feels intimidated by the manual process.

RichJohnson · Post by **RichJohnson** » Wed Jun 25, 2008 8:40 am

I really want to get the jeep running again right now.
I may do the alternator swap on the dodge m,37 right now and salvage its regulator and get the jeep going.
Then take the dodges generator and cables and the jeeps regulator in to them to see if it can be fixed.
It just smoked for barley a second, not much. But one prong on the circut breaker contactor is bent upward and I dont think it will straighten out to be usefull.

This whole thing has turned into a disaster for me. I had no Idea that the regulators were so delecate, and so un supported these days. I heard alot of stuff the last week, most people have either never heard of a carbon pile reostat or havent seen one in 40 years.

I am contemplating the solid state unit, does it require rewireing of the gages or anything else, I seem to recall it uses a volt meter rather than an ameter.

Thanks for all the help, I think I would have gotten it down with afew more hours of connecting and disconnecting the batteries, I was close with the ammeter, it was showing more charge than discharge. If I hadnt dropped that darn pliers on it.

Post by **wesk** » Wed Jun 25, 2008 10:01 am

The carbon pile resistor has been with us from the 18th century thru today. I can't believe those technicians you spoke with have no idea what they are operating when they turn the "Load Knob" on a Sun or Allen generatgor/Alternator tester or battery load tester.

Sci-Tech Dictionary:carbon pile Sponsored Links Carbon pile
(′kär·bən ′pīl)
(electricity) A variable resistor consisting of a stack of carbon disks mounted between a fixed metal plate and a movable one that serve as the terminals of the resistor; the resistance value is reduced by applying pressure to the movable plate.

From the Delco Remy Tech web site:

1-24. APPLYING AN ELECTRICAL LOAD WITH
A CARBON PILE. (See Figure 1-15) The carbon pile
is a variable resistor designed to carry high current. A
carbon pile, along with a voltmeter and ammeter, is
normally an integral part of a modern battery tester.
In addition to load testing batteries, carbon piles are
used to test starter and alternator circuits.

This is from the test procedure for a 1995 Cadilac:

CAUTION: Carbon pile testing is part of this procedure. To avoid
battery explosion, turn carbon pile OFF before connecting
to or disconnecting from vehicle battery.
5) Disconnect negative battery cable. Install ammeter to
voltmeter. Connect voltmeter to generator output (BAT) terminal.
Connect negative battery cable. With load off, connect carbon pile
load tester across battery terminals. Run engine at approximately 1500
RPM, turn accessories on and load battery with carbon pile load until
maximum generator output is reached. Adjust carbon pile to maintain 13
volts or more. Measure amp output.
6) If amp output is within 15 amps of rated output, generator
is okay. If amp output is not within 15 amps of rated output, repair
or replace generator. See GENERATOR USAGE/AMP OUTPUT RATING table.

This is currently for sale on Northern's web site:

Schumacher Carbon Pile Load Tester 500 Amp, Model# PST-500

Variable load carbon pile tester offers maximum accuracy when performing battery load tests on 12V battery systems. Separate voltmeter and amp meter provides easy-to-read battery load tests...

$299.99
at NorthernTool.com Overall Rating: 8.6
NorthernTool.com

That's just a quick sampling of Carbon Pile articles available on a simple google search. Based on the above data I believe the technicians you have been talking too need serious professional help.

Now that I've established the carbon pile tester as a key ingredient in modern day auto-electric trouble shooting we can move on and I hope you have better luck locating modern, well trained technicans in your area.

The transistorized regulators do not use the 8 & 9 wires currently connected to your amp meter. They do not have the internal amp meter shunt that the old mechanical regulator has. You will hear some folks tell you to just connect the positive side of the later M series voltmeter (Also know as a "generator condition gage" to either or both of these 8 & 9 cables. That's a no-no. Connect the plus side of the voltmeter to the #27 instrument panel spider harness. This way the volt meter is only hot when the main switch is on. You will need to get a heavy truck #27 spider harness that has the extra 5th leg. Then connect the voltmeter negative side to the firewall not the instrument cluster. Tape up or cap the 8 & 9 wires.

In the interest of safety and preventing future accidents why not install a battery cut off switch? This will also make it quick and easy to add or remove battery power.

RichJohnson · Post by **RichJohnson** » Thu Jun 26, 2008 10:47 pm

Thanks for the tutorial on the sold state regulator.
I have so far resisted it.
But, to make that circut work, wouldnt the 8 & 9 wires need to be connected together to provide power distribution?

In other news. I just installed the 60amp alternator kit in my M37. It was a fun install. Took the pully off the generator and put it on the alternator and followed the instructiions.
This was easy since I have a B1 1965 model that has a voltmeter rather than an ammeter. The wire that energizes the alternator splices ino to circut 27. I connected the + wire back to the batteries and then touched the ground to test for a short, then I turned the on switch and tested again. All good. Then fired it up and adjusted the voltage. The voltmeter fell right where it should on the white dot in the green zone. Before with the generator it was always a bit low.

So the million dollar question.
Since the truck had a volt meter there is a slight doubt in my mind that the regulator couldnt be installed in the jeep, (accutally a friend suggested it).

The insides appear the same even though its not an Auto Lite and has a different cast base and looks kind of taller.
The plugs are the same, and I would think that M series parts are, well M series parts, interchangeable.

Your opinon before I do it.

Im going to take a pic of the damaged regulator once I get it out. Maybe some hobbyist thinks they can fix the contactor.

Post by **wesk** » Fri Jun 27, 2008 1:29 am

The amp meter in the jeep is an externally shunted amp meter. That means the actual heavy current used in the jeep's systems Does Not Pass Through The Amp Meter. It comes in on the #10 wire. The #10 wire at it's beginning in the regulator passes through the shunt. The #8 and #9 wires are connected to the current sense terminals of the shunt. They sense the amount of current flowing through the shunt by inductance and deliver a very low amperage signal to the amp meter. You could cut both off the back of the amp meter and if the regulator and generator are in proper condition you will have no problem with the system, you will only loose the amp meter's indication.

The transistorized regulator does not use the two pins that the #8 & #9 wires were attached to. So no signal to anything on #8 & #9. So if you want to monitor the system's condition you will need to cut the #10 wire and install a shunt in series with it and connect the #8 & #9 wires to the sense terminals of the new shunt, or get a heavy internally shunted amp meter and feed the 10 wire and all system loads through it, or install a voltmeter as I explained earlier.

If the voltage regulator you had in the Dodge was a 24 volt 25 amp unit and not an Auto-Lite then it was most likely a Delco Remy 1118656, or 1118606, or 1118546. All are interchangeable with each other and the Auto-Lite unit. All four will work with either generator Delco or Auto-Lite. If that Delco worked ok in the Dodge all you should need to do is install it and run it in the Jeep.

Transistorized voltage regulator.

Auto-Lite regulator

Delco 1118606 regulator.

Transistorized regulator wiring. Note B and D are marked no connection. That means they have nothing wired to them inside the regulator.

Auto-Lite regulator wiring. Notice all four pins have internal connections which also include the shunt. Although the illustration doesn't show it, there are four terminals on a shunt. The two heavy terminals that carry the main current through the shunt and the two small terminals for the two sense wires.

Delco 1118606 regulator wiring.

RichJohnson · Post by **RichJohnson** » Sat Jun 28, 2008 1:50 pm

Ok, I swaped the regulator from the dodge to the M38a1.
Unfortunealtely the ammeter reads negative more than positive, and the batteries only get around 25 volts.
I guess I have to go through this all again.

I wonder how the m37 ran so well with this setting for so long. Its voltage was always just a tad below the optimum mark.

Is it possible that just because I have a different generator hooked up to the regulater now, thats why the settings are low?