Need Guidance in solving 200A dual voltage alternator issue.

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Need Guidance in solving 200A dual voltage alternator issue.

Post by RockHillWill » Fri Mar 16, 2018 6:11 pm

After mounting slantback items to a 1991 troop carrier, I happily drove around for about 120-150 miles oblivious the fact that the alternator was only charging to the lower third of the voltmeter yellow section. After realizing that I might need to review the alternator/charging system I began to try and figure out what is happening. I am not very knowledgeable about electricity, so it has been a slow process. Batteries read 23.8 - 23.9 running or not. Checking at the voltage regulator we could read as high as 15v on the 12v side, but no way could ever get more than 23.8-9 on the 24v side. Long time member of a local National Guard motor pool stated that the voltmeter was showing correct voltage based on the readings that we were taking. We tried another 'known good' used regulator = NO change! I purchased a 'tested good' 200A DV alternator and regulator unit, but it was damaged in transit, and am awaiting insurance inspection. In the meantime, I took that regulator off that one and tried it. NO change at all! Travelled to Greenville, S.C. this morning to get a rebuilt alternator and regulator (guaranteed). Installed them both and got the same readings. Switched and tried my original regulator and the regulator on the 'damaged' alternator and they both showed NO change. Turned on the lights, but that showed only a very minor drop in the voltage readings. Have previously cleaned all the related terminal ends and have installed a new Kascar grounding harness. Took care to always disconnect the battery before working on any terminals. Truck was shown to have only 2680 miles when I picked it up. I was skeptical, but this truck is EXCEPTIONALLY nice and clean. The batteries are both clean and dated 2014 (original type per the NG motor pool guy. Water is at the correct level, water is clear and the plates show no shedding or accumulation. Both batteries check within .1 volt of each other. I recently installed a battery disconnect switch at which time I cleaned all the terminal and cables. Took photos of the wire connections at the regulator as they were on arrival, and have tried my best to look at the wire schematics in the TM's, but I am having difficulty reading them. Any suggestions???? Thanks!

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Re: Need Guidance in solving 200A dual voltage alternator issue.

Post by johncarrol » Sat Mar 17, 2018 9:49 am

I feel for you as I and many others have thrown more and more money at a problem to find out the solution was a simple inexpensive fix. I had a similar problem last year with a dual battery 6.2NA GMC pickup. When running, volt meter read 11-12 volts. checked each unhooked battery (11-12 volts) I noticed my starter cranking speed had been less and less and because my volt meter was showing less than 14 volts engine running, I thought the problem was with the charging system. I got out a cheap, but valuable tool to me: a battery load tester from Harbor Freight. I checked both batteries unhooked from each other and found out that one had a bad cell or cells and when connected to the other would pull the others amperage, not voltage down with it enough to make me think the problem was with the charging system. A volt meter connected to the bad battery would still read 12 volts to me. Both my batteries were purchased at the same time and were only 2 years old. A load tester is nice for checking batteries to tell you when they are about to let you sit along the road somewhere. I truly hope you fix your problem soon, so you can enjoy driving your HMMWV more without worries. they are awesome!

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Re: Need Guidance in solving 200A dual voltage alternator issue.

Post by Augi » Sat Mar 17, 2018 9:51 am

Are you measuring the 24v side of the regulator at the regulator or at the upper battery post? Is there continuity between the two? Try running an external wire (4ga or larger) as a test between the 24v post of the regulator and the upper battery postive post.

Do you have the big flat ground strap installed between the alternator and intake manifold?

Is the ignition/sense wire hooked up to the regulator properly? If you converted the truck from a 60a alternator the big wire that was the charging wire for the 60a alternator doesn't go to the 24v post of the 200a alternator.

When you measure 23.9v or whatever you are measuring the battery voltage. The alternator isn't charging. When the alternator comes up it will raise the voltage to 28ish.

These big alternators take some time to build the field in the windings when you start the truck. I usually have to hold the engine at high idle for 5 seconds or more to get it to start charging.

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Re: Need Guidance in solving 200A dual voltage alternator issue.

Post by RockHillWill » Sat Mar 17, 2018 5:31 pm

Hey, guys, big thanks for the feedback.

Just this afternoon, I borrowed a known good battery load tester, and will give that a try tomorrow.

It does have the large woven strap and I did clean the connection at the alternator. I will now clean the connection at the intake manifold. The 200A DV alternator came with the 1991 troop carrier. I am a REAL novice at electrical and the testing has been random connections, just checking to find some voltage, somewhere. Is the '24v side of the regulator' the small wire at the terminal marked AC? Is the 'upper battery post' the very large wire connected to the side of the alternator with a large red boot? If I run a #4 gauge wire between the two, what should I expect to see? or happen? As for holding at a 'high idle', we did NOT do that after changing to the newer alternator/regulator but did make small/slow increments to the RPM looking for a change in the charging rate, and saw little or no increase. Prior to changing the alternator/regulator, I did look for any changes in the output at different RPMs when driving, but did not notice any change. I will certainly try the raised RPM idea before trying the other suggestions.

Thanks again for the help. I will try each of the suggestions.

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Re: Need Guidance in solving 200A dual voltage alternator issue.

Post by Augi » Sun Mar 18, 2018 6:26 pm

The 24v side of the regulator is the post where the giant cable with the red rubber boot is attached. The upper battery post is the + terminal on the forward battery in the box under the commander seat.

The cable from the 24v side of the regulator should run directly to the upper post of the battery. If it isn't connected for some reason, running the extra wire in it's place is a quick and dirty check to tell you. If you hook it up and it charges, figure out why the big wire isn't connected.

Read my dual voltage alternator post from a while ago and look at the pictures to see how the wires should be hooked up.

It's possible that the previous owner of your truck replaced a 60a alternator with the 200a but didn't hook all the wires up correctly.

Augi


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Re: Need Guidance in solving 200A dual voltage alternator issue.

Post by Retired War Horses » Mon Mar 19, 2018 7:42 am

Need to post pics of what your install looks like....Also, the 200 amp will not show output for about 30secs after startup, that can throw some folks off. I have seen many many times here in the shop, a bad EESS will prevent charging.
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Re: Need Guidance in solving 200A dual voltage alternator issue.

Post by RockHillWill » Mon Mar 19, 2018 5:44 pm

Thanks again guys for your responses.

Here are a few pictures of what I am working with. Since the last responses, With the rebuilt alternator and regulator from KASCAR installed, I have checked for continuity from the positive terminal of the forward battery to the large red cable fastened to the alternator that's covered with a bright red boot and found that I DID have continuity.

I did start and run the idle up for two minutes and saw no increase at either the yellow portion of the voltmeter or any change from the 23.7v reading on the hand held meter that I had connected between the large red covered cable and a ground on the alternator.

I had been told that if I disconnected that terminal as shown in the first picture, that If I connected a volt meter between the opend connector that I should read 24v. (something about an 'exciter'???)

All changes were made after disconnecting the batteries at the disconnect switch.

I went to the motor pool at the N G Armory and they loaned me a known good EESS, similar to mine, that they use for testing. There was NO change of any kind in any of the readings. The yellow EESS is mine, the green EESS was from the motor pool.

I did go back and read Augis previous post, but I am unable to review a known good wiring schematic and could not correlate the 'numbers' to a known location. The guys at the motor pool had a TM number that was for the Humvees that ended in -23 (I think) that did show wiring schematics, but I have not been able to locate that TM to download. Any help there????

Thanks again!
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Re: Need Guidance in solving 200A dual voltage alternator issue.

Post by Retired War Horses » Mon Mar 19, 2018 5:52 pm

What are all those extra wires landed in the IGN Connection?
You should have 2 small wires only, the old engine harness lands to ground on the ground strap.
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Re: Need Guidance in solving 200A dual voltage alternator issue.

Post by 86humv » Mon Mar 19, 2018 8:37 pm

The 14 volt tap needs to go to ground on V belt trucks
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Re: Need Guidance in solving 200A dual voltage alternator issue.

Post by RockHillWill » Tue Mar 20, 2018 6:55 am

More details:

Cleaned the intake manifold ground (It looked like it needed it!) but NO change.

Recorded the wire numbers to the alternator and regulator (see new pic)

"The 14 volt tap needs to go to ground on V belt trucks"
I am nervous to do that after reviewing this thread that states that the 14v terminal is connected to the positive terminal on the rear battery. It is shown as a 'belted' system. I am confused about that idea.
viewtopic.php?f=63&t=221530
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Re: Need Guidance in solving 200A dual voltage alternator issue.

Post by Retired War Horses » Tue Mar 20, 2018 7:49 am

Why are you grounding IGN? As I said....you should only have 1 wire on each of the studs on the regulator, forget about the 14v tap, you truck is not a 4L80E equipped truck, and yes, the TM calls for grounding the 14v to the rear 1/4-20 regulator mounting bolt of used in a v-belt application.
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Re: Need Guidance in solving 200A dual voltage alternator issue.

Post by 86humv » Tue Mar 20, 2018 8:26 am

Take the ground off IGN., and ground the 14v tap.
14v tap is per Niehoff in your application.
M997 A0/A1 dwg. F0-3 says: 5A, 568 TO Ign....2A to A/C tap.
This is on a single output reg. on a 200 amp Alt.
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Re: Need Guidance in solving 200A dual voltage alternator issue.

Post by RockHillWill » Wed Mar 21, 2018 4:19 pm

I have found the problem, but not fixed it at this time.

I spent some time today talking to KASCAR (Big fans of you Steve) and at the NG Motor Pool and reviewed that M997 AO/A1, making sure that I was looking at the Fold Out #3, and called John Haines at Niehoff. As a result of these encounters, I decided against having anything to do with the 14v tap.

I did remove the KASKAR ground harness lead from the regulator (purely a mistake on my part in reading instructions!).

What I did do was check to see if I had 24 volts at the IGN tap and found that I did NOT! I ran a jumper wire from a 24v terminal at the batteries to the IGN tap. The volt meter ran right over to the middle of the green as soon as the motor started. No waiting, no revving up. The next step is tracing down that series of wires, cannon plugs, etc. to see if I can find the source of the problem, but I am much happier now knowing what I need to do.

Thanks again guys for all your help!

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Re: Need Guidance in solving 200A dual voltage alternator issue.

Post by Action » Wed Mar 21, 2018 5:16 pm

Your meter went straight to the middle of the green as soon as it started? mine takes about 30 seconds with the 200 amp.

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Re: Need Guidance in solving 200A dual voltage alternator issue.

Post by RockHillWill » Wed Mar 21, 2018 5:23 pm

Maybe it did not 'jump' to the middle of the green, but certainly didn't take 30 seconds. Just looking the clock, I would say about 10-15 seconds. I was also 'jumped' directly to the IGN, maybe that has something to do with it. I was so happy to see the movement, I only kept it running for about a minute. The Niehoff troubleshooting #TG0017B says that a 'soft start' may take up to 10 seconds at full load.

Here is a link to that information for the alternator N1225-1 w/ regulator N3135: http://www.ceniehoff.com/Documents/Ctrl ... 200562.pdf

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