M1010 charging problem

[waorth]

As a M1008 owner I'm not that familiar with the M1010 electrical system.
What would cause the front batterie to undercharge and the rear one to overload?
From the manuals I know there are two 24v alternators (200amps each!). So that means up to here it is a true 24v system. Now the 24v where transformed to 12v by a regulator(?). Is this correct?
The manual also points out that one alternator feeds the the front batterie (12v) and the other one charges both batteries (24v). Ok, this is usual on all of the CUCV.

Could the regulator cause the problems? Is it a common part to fail? Is it just a DC-DC 24v to 12v converter? Then it shouldn't be a problem to replace it by a stronger, reliable part (maybe a boat or truck outfitter is a good source).

One thing to mention: If my friend (the owner of the M1010) adds an additional load (like a blower or a 12v freezer) everything seems ok.

Anyone have ideas or a fix of this problem?


Regards,
Walter

[britannic]

I remember reading in the lost scrolls of this forum, that the M1010 had a design flaw in the charging system that causes the symptoms you describe.

You may want to download the military manuals and check out the wiring diagrams @ http://www.hmmwv.org/HMMWV/pubs.htm

[ 12-26-2003, 06:22 AM: Message edited by: britannic ]

[Peter J. Bierman]

The truck normal electrical system runs on one battary, the second is only used for starting and the glow system whitch are 24V.
You might suspect one generator to be bad.
Follow brittanic's link and find out.

Good luck Peter

[britannic]

FYI: According to the military manual I have, the M1010 uses a remote regulator, as opposed to the integrated ones in the M1008/9/28 alternators.

[waorth]

thanks a lot for your quick answers. Like in the old days with the DP mailing list. ;)

@britannic:
I think the regulator mounted on the fender(?) is in addition to the ones integrated. At least this is what the exploded view in the manual of the M1010 alternators shows.

If one of the alternators is bad (hopefully not both of them), swap places could limit the problems. We will see . . .

regards Walter

[britannic]

There are internal regulators in both alternators as you say, I'm assuming the external one is to handle both alternators at 28-29.1v?

[88 K30]

Whew! I totally missed this one. The holidays had me too distracted, I guess.

The M1010 charging system is quite an interesting animal. It was also found on a very few M1028 trucks, as well (which is why I have some experience with it - my truck is one of the few).

The system uses a pair of 100-Amp, 28V Leece-Neville alternators, as opposed to the 100-Amp, 14V Delco units in the rest of the CUCV series. The system employs a "DUVAC" (Dual Voltage Alternator Control) unit (large, blue box on drivers fender) to provide 14 and 28 volt power. It switches back and forth between charging only the front battery and charging both batteries in series, depending on the system's requirements. It uses an external regulator (smaller blue box on driver's fender) to sense both the 12 and 24 volt systems, and allows the DUVAC to charge either side as needed.

The original setup was supposedly not charging the front battery from the factory. The engineers determined that the system could not properly sense the voltage, and so, they came up with a fix (affectionaltely know as the "Orange Wire Kit"). This kit contained some heavy orange wire to replace parts of the existing harness, as well as diodes to be installed. This really never fixed the problem either. The trouble, from what I could see with a volt meter, was that the system never switched to 12V mode, so the front battery never got recharged and the top alternator was charging 24V in series. Meanwhile, the other alternator was also charging 24V in series, so the rear battery was seeing more amps & volts than it needed, while the front saw less than it needed. The rear overcharged and the front slowly died. I have never seen a surplus M1010 without this problem. Everyone I know who has one, has the problem.

I fixed this problem by running the top alternator in 14V all the time (70-Amp output), since I don't really have the need for 200-Amps of 24V power. This has been working well for me for about 8-9 months.

The other problem with this charging system is that there seems to be a current drain if the master switch is left on. For me, it has not been consistent, but I think I have seen it once or twice. Switching the master off seems to prevent it.

I am interested in the fact that an extra 12V load seems to fix the original charging problem. Did you verify this with a voltmeter? How much load are we talking? I would possibly like to test this on my truck. Can you give more details?

[waorth]

hi 88 K30

thanks a lot for your reply. These explanations seem to bring a little more light into the mysterious charging system of the M1010. Although the standard CUCV electrical system sometimes appears a little "strange" to me :confused:

In your modified system one of the Leece Neville alts is fed by only 12volts, thus charging the front batt with 14 volts?
Are the DUVAC unit and the external regulator still in use?

Unfortunately I' can't give you more details about the extra load thing now, because at this time I'm only emailing with the owner of the truck (some 20 miles away). As soon as I will get any information I will let you know.

Thanks again for giving me this valuable information.

Regards
Walter

[88 K30]

The Leece-Neville units actually have an internal regulator that can be adjusted to low, medium, or high. I believe some people have tried to switch this to the low setting to get only about 14V from the top alternator, but that is not the way to go. The trick is the external regulator. It is designed to sense both the 12V and 24V circuits, and never let either one exceed their respective voltages.

My setup still uses the original regulator and DUVAC. Basically, all it comes down to is switching 2 wires on the DUVAC unit itself. I actually made a web page up several months ago about my "fix" for the system, since nobody else I've ever talked to (including the Army, apparently) had been able to fix it. It details my entire "discovery" process. It also has a few good links to PDF files from TACOM and Sure Power (makers of the DUVAC). Here is the link...

200-Amp Charging System Fix (http://www.toadmail.com/~cucvfan/200AmpCharge.html)

Hopefully, this will help your friend out (and enyone else with an M1010). I am still very interested in the fact that an extra 12V load seemed to fix the problem. That would indicate that something else is going on inside the DUVAC, which is not being explained in any documentation, and might help explain why the system appears not to work on most trucks....

[waorth]

You did an excellent job by researching all the data concerning the 200amp charghing system. My hat is off to you.
Maybe TACOM is interested . . . ;)

The (modified) CUVAC solution might also be an option for the 100amp series CUCV. With that I would be able to run just one 24v alternator and gain a place to install other goodies (i.e. a belt driven compressor for onboard air or a separate pump for hydraulic winching).

[Peter J. Bierman]

That one of the reasons I did the conversion,
needed the bracket for airco compressor.
Besides that one generator was gone ;)

Peter

[waorth]

Okay, I'll try to explain the odd thing with the extra load on the system. I feel sorry that I'm not that familiar with

a) electricity
b) english language

so please, be patient with me, still learning ;)

While driving and switching i.e. headlights and wipers on, you notice the 2 voltmeters doing opposite things: 12v instrument drops from 13v to 11v while the 24v instrument rises up to 16 volts. If now other 12v sources like blower and cooler are added, the voltage seems to come back to somewhat "normal" conditions:
12v instrument rises up to 12.5 - 13v, 24v instruments reads 15 - 15.5v.

Again, I'm just a shade tree mechanic but learning from the DP and its members keeps my wheels turning.

Walter

[twaddle]

Hi there,
Check the voltages with a digital multi meter just to check the accuracy of your gauges.

Also check that your drive belts and pulleys are in good condition.

I recently had trouble with low voltage readings and one battery losing charge on my M1008 pick up.
It turned out to be a drive belt getting shiny smooth, causing slippage.

Good luck

Jim Twaddle
Biggar, Scotland

[dieselcrawler]

Yeah, what they said.... *grin*

For sure check your v-belts... I've been knockin' myself out for the past 3 weeks over a charging problem on my M1028, turns out that I'd bet that half the problem was worn out belts. (Bad voltage regulator was the other half!) Good belts, nice and snug, and the ol' 'Crawler is good and juiced up... but best of luck on your repairs.

Greg