Since we purchased it maybe three years ago, the wife's truck has went through FOUR voltage-regulators; one went wild, blew the head-lights, and boiled the battery almost dry; the other ones simply quit charging; this last one the good blue MOPAR.

The rest of my Dodge fleet are still on the MOPAR regulators that I put on them a couple years ago with no issues.


Are these frequent failures just typical for Dodge/Cummins, or is something causing this, and if so, what ??

Other that just swapping regulators, how does one discern if the problem is the regulator or the alternator ??



I am for sure going to mount TWO new regulators, side by side.



And, I am contemplating wiring them through a DPDT switch, such that when the voltage starts dropping, a mere flipping of the switch will bring the second regulator into play, without having to shut the engine off with a weak battery.

Then, at the soonest convenience, I can replace the faulty one with another new one at the ready.

 

More of the story :


A brand-new Group-31s battery was installed in January.

It went bad and would not charge, nor hold a charge, about two weeks ago.(voltage check at the battery with engine running 13.9 volts)

I temporarily installed a three-year-old Group-24 Walmart that I had, so she could drive the truck.

For about two weeks, it started easily, charged fine, everything okay.

The new replacement battery showed up Friday; I installed it Friday evening; everything checked out okay.


Yesterday (Tuesday), she calls from work and it is too weak to turn over.

She jump-started the truck and drove it home; dash gauge showing 10 and dropping all the way home.

I get home and check battery voltage = about 11-volts.

I re-install the old Walmart that had been sitting un-molested since Friday night; it fires right up; but, voltage is low and steadily dropping.

I start-up and test the running voltage on the D-350(a different truck) = 14.2-volts.

I swap the regulator from the D-350 onto her truck, crank it up, and voltage showing a steady 13.9 with the Walmart battery.

Okay, problem solved (or so I thought).

I re-installed the new Group-31, jumped it off, and everything charging fine, let the engine idle for quite some time, voltage showing about 13.

On the battery guys recommendation, I put the charger on it all night; charger set at 10-amps.

Just a few minutes ago, I went out and removed the charger; non-running voltage showed 12.2 = not the 12.6 I wanted to see.

The engine whirled right over and started.


BUT, an immediate voltage check, engine running, showed only 12.15 and slowly dropping.


Headlights and wipers on, and voltage dropped into the high 10s; lights and wipers off and it barely went back to the high 11s.

OBVIUOSLY, the alternator is NOT CHARGING again.

Another DEAD regulator ?????On update: YES, deader than a door-nail(I never did know exactly what a door-nail was.).


Remember, when I borrowed the "known good" regulator, idling voltage with the "known good" Walmart battery was 13.9 last night, not hardly so good with the re-installed weak battery (which I attributed to the battery voltage being low), and no charge at all this morning, AFTER sitting all night with a "known good" charger on it.



Is it possible that this new battery is killing regulators ??


All of the good old-time battery/alternator men around here are laying over at Haven Hill Memorial Gardens, and all of the newer guys can only function when they know what kind of "code" it is throwing.



Ideas please.

 

Does the regulator have a good ground? How is the condition of the wire from the alt. to the battery?

Worn brushes in the alt. can cause intermittent "no-charge" problems.

The battery can't hurt the regulator.

 

Regulator has a dedicated GROUND wire.

Afraid to waste anymore high-dollar regulators (two in one day), I picked up a $16 one at Advance.

Just for fun, I replaced the regulator that I had borrowed back on the truck it came from; it is for sure a dead soldier.


Another thing I noticed :

This truck came equipped with a VDO tachometer, along with a tach-feed-wire that someone had installed into the alternator; with a dud regulator, the tach is erratic; with no regulator, the needle lays still on zero.

I had noticed several weeks ago the tach acting weird; before I got time to diagnose it, it went back to operating normal; probably something fishy was going on then.



Just a few minutes ago, I started the engine with the regulator un-plugged and a long jumper-wire in the plug's GREEN/FIELD terminal.

With the engine running, when I grounded the jumper-wire, the alternator would engage and voltage would steadily climb to level off at 14.65-volts on my digital meter.( I sort of expected more ??)

I tried this a number of times with the same results.

I took my jumper-wire into the cab; the tach was on zero; when I would ground the jumper, the tach would immediately operate normally.


I am about afraid to plug in the new regulator; I am not sure it is worth sixteen-bucks to see what happens.

 

Can these worn brushes kill a regulator ??

 

Here are some excerpts from a leaflet that came with the new regulator :


4. Before installing new regulator, check for a short to ground in the wiring from regulator to alternator field.

If such a short existed, would not it behave the same as when I purposefully shorted the "field" with the regulator un-plugged ??


6. Be sure rectifiers are not shorted or open.

How do I check the rectifiers ??


7. After the previous checks have been made,
a. Remove plug from regulator.
b. Insert jumper-wire into the "field" terminal of the plug.
c. Start engine.
d. Run the engine at idle and GROUND the jumper-wire. The meter should indicate a (+)charge. If not, there is trouble that must be addressed before the new regulator is installed.

Been there and did that = charging 14.65-volts.



I fear that, should I plug in the new regulator, it is just gonna get killed.


Thanks.

 

You should get way more than 14.65 volts with the alternator full fielded. Even at idle you should have seen 16-18 volts.

It sounds like something is wrong with the alternator beyond brushes. Have you checked the AC voltage? More than about half a volt means the rectifier is bad.

 

Okay, to check AC voltage;

1. I set my meter on ACV 200 , right ??

2. I proceed by testing at the battery terminals, just like a DC voltage test, right ??

3. Is the regulator plugged in or un-plugged for this ??

4. If the regulator is plugged in, I assume it would need be a good working one, right ??

5. If the regulator is un-plugged for this test, I assume I will need jumper the "field" to perform the test, right ??


Thanks.

 

When my alternator went bad, the brushes were pretty worn, but what really made it go was the rectifier. I was getting feed back through the radio, so I was trying to test for AC voltage with my voltmeter, but never could figure it out. So I went to autozone and had it tested with they're machine and it confirmed what I thought, the rectifiers were bad. So I took it to the rebuild place and he said that besides the rectifier being bad it was only putting out like 60amps, haha, and it was cheaper to buy a reman than for him to rebuild it.

But if you figure out how to test for AC voltage with a volt meter, i'd like to know!

 

UPDATE


Engine running, regulator un-plugged, AC-volts (at the battery) = 25.6-volts

Same situation with "field" jumpered to GROUND - AC-volts = steadily climbing = I quit at 32-volts and still climbing.


Do these numbers look typical for a failed rectifier and that I performed the test correctly ??


Thanks.

 

I would have to say that any AC voltage at the battery is NOT good.

 

MORE UPDATE

Installed an extra alternator that came off an extra engine = history/condition un-known.

Regulator un-plugged, field open, ACV = 25.5
With field grounded, DCV = 15.5, ACV = keeps steadily climbing.


So..................., and now I am getting really puzzled.........., (Keep in mind that all of these vehicles have not been any problem.).... I checked the following vehicles :

My Ford/Cummins, all Ford 1G charging-system, DCV = 14.2, ACV = 30.8

Old extra knockaround 1990 Dodge/Cummins that sits for weeks and starts at first touch, DCV = 14.4, ACV = 26.7 (with one of the DEAD regulators from the wife's truck plugged in)

1990 Cherokee, inline six, all stock, always starts, always runs, voltage gauge does act wacky though, DCV = 14.5, ACV = 31.2


Wall socket by the back door, ACV = 120.1


Either I am doing something wrong, or I have a whole fleet with bad alternators. (Which is very possible considering that the newest of the bunch {seven trucks} is the wife's 1991.5.)



I set the meter on ACV 0-200, red probe on positive battery-terminal, black on negative; I am doing this right ain't I ??

 

MORE UPDATE


Extra alternator installed, chinese regulator connected, DCV = 14.3, ACV = 30.8



Although the ACV is way too high, it is not so bad as the one that was killing regulators.

I am going to turn her loose with instructions to keep a weather-eye on the VOLTs-gauge, and to immediately turn OFF all un-necessary electrical and head to the house should the gauge start to falter.





In the meantime, I am going to repair/rebuild the other one.


Where can I order a replacement rectifier-bridge and other repair parts for these alternators ??


I have looked at dozens of alternator sites and can only find minimal parts for them.



Thanks.

 

I'm not sure why you are getting such high AC readings, there's no way you have that much AC on all those vehicles. What kind of meter are you using?

 

Just a plain old rectangular-shaped digital multi-meter that has so far served me well for several years.

Not doing the exact same tests, I have cross-checked it against various other meters and they always agree within a hair or so.


I do have another brand-new never-been-out-of-the-package one buried somewhere within the many hidey-holes of my truck; I will dig it out and see what it says.

Also, I intend to check some of the much newer vehicles at the shop, just for comparison.


Thanks.