Batteries not holding a charge

[kenz5380]

I have a 1985 m1008. I've only had the truck for two weeks and i've been fighting the same issue the whole time. The starter relay went out the first day i had it and i did the recommended fix described in the sticky thread above. The relay works and the starter works, but every time i leave the truck parked for a couple of hours i come back and the batteries are drained.
I should mention that i did replace the two alternator system with a single 24 volt single wire alternator, and i'm not sure if that is the issue here. I also replaced both batteries with brand new ones thinking maybe they were just bad.
The neg. Battery cable doesn't arc when i pull it off with the engine not running so if there is a draw on the system when it is not running it is not a big one. The gauge reads in the green when i first turn off the truck but just a few minutes later it is down in the yellow and then in a couple hours they are dead.

Any ideas?

I'm looking at the alternator relays next to the starter relay under the dash thinking that they are doing something wrong with the new charging system, but electrical is not my forte and i am not certain what they even did originally.

 

[Warthog]

Welcome to SS.

A one wire 24v alternator is not the correct answer. The stock alternators are 12v each. The system is designed for each alternator to charge one battery. You are on your own with the one wire alt.

If you had left the truck stock, someone from accross the world would have been able to help dianose the problem.

Good luck

 

[Warthog]

Make sure you visit the Cucv Wiki - Steel Soldiers::Military Vehicles Supersite (CUCV Wiki) that is at the top of the page on the CUCV Forum. All of the CUCV Technical Manuals are listed and many other helpful bits of information.

Make sure you download the repair manuals. You can get then for free. A couple of our members have posted them on their websites.

Also the wiring diagrams are in the appendix of the -20 and -34 manuals.
JATONKAM35s HOME ON THE WEB


Almost every question you will have has been asked and answered many times. The advanced search will become your best friend. Please don't hesitate to ask something that you can't find.

Read the TM 9-2320-289-10 Operators Manual to find out how a stock system should work. It is simular to the Operators Manual for Civilian vehicles. It tells you where all the lighs, switches, etc are located and what they do.

Three of the most important tools you can buy are:
Voltmeter and know how to use it - ~$10 and up
12v Battery Charger - ~$50 for a decent one
Battery Load Tester - ~$30 for an okay one at Harbor Freight

Warthog

 

[Sephirothq]

get an amp meter and check your draw to the batteries.
This is done by putting the meter in series to the battery and the post. IE Remove the terminal from the ground of the battery put the lead from the meter to the post and th eother lead to the cable to connect it.

This should only be used for checking small loads otherwise you will either blow a fuze in the meter or ruin it.

Now if you have a voltage load remove the wiring to the alternator.
Do you still have an amp draw??

Alo check the voltage at teh batteries with the engine running. YOu should have 14 volts or so at each battery a total of 28 volts

IF you don't then there is your problem.

Bottom line, you need a meter. Anything else is just guessing.

 

[kenz5380]

I'll def check the draw with a meter, that's good advice.

As far as leaving the truck stock, that wasn't an option. I bought it with no alternators at all so I used what was available. If I have to back to the stock configuration I will, but for now I want to try to make what I have work.

 

[mistaken1]

The gauge reads in the green when i first turn off the truck but just a few minutes later it is down in the yellow and then in a couple hours they are dead.

Any ideas?

Does your voltage gauge show a voltage reading when the key is in the off position?

If you are draining fully charged batteries in just few hours that is a pretty serious drain.

A quick work around is to install a battery cutout switch but that does not fix the problem it only buys you some time to fix the problem.

Who installed the the 24V alternator? I see in the above post.

I'm looking at the alternator relays next to the starter relay under the dash thinking that they are doing something wrong with the new charging system, but electrical is not my forte and i am not certain what they even did originally.

No idea what you did to the charging system so I am afraid I can't be much help either.

 

[Warthog]

The truck is designed to have most of the electrical running on the 12v front battery. The drivers side alternator charges that one. Only the starter and the GlowPlug system are 24v and use both batteries. The passenger side alternator charges the rear battery.

Your 24v alternator setup will not be able to "keep up" with the drain on the front battery.

If you want to use one alternator then take a look at this. It uses a 12v alternator and rewires the batteries.

 

[kenz5380]

no the gauge does not read when the key is in the off position, I meant when the truck was off, but when the key is in the run position

 

[jbclassix]

I'm sure I'm going to get slammed for this, but here is a Link to the 24V alternator conversion.

 

[Warthog]

No need to be slamed. We always enjoy new ideas.

Your install looks very clean, professional and documented. Did you cut the removed wires or did you tape them up for any future owners?

I see your in Colorado Springs. Is the truck you did the conversion on the one we are talking about in this thread?

And just an FYI, You do need to put a location in your user profile. Part of the site rules.

 

[kenz5380]

The truck jbclassix posted the conversion details on is my truck. If any of you guys feel motivated to go to his link and check out the conversion I'd still appreciate any input.

 

[Warthog]

The truck jbclassix posted the conversion details on is my truck. If any of you guys feel motivated to go to his link and check out the conversion I'd still appreciate any input.

I've been there and I am looking over the documentation he provided.

 

[Warthog]

Please clarify something. You said it was a single wire alternator, but the diagrams he provided show a two wire setup. Can you tell us which it is? and if it is a single wire where is it hooked too?

Good looking truck by the way.

 

[jbclassix]

No need to be slamed. We always enjoy new ideas.

Your install looks very clean, professional and documented. Did you cut the removed wires or did you tape them up for any future owners?

When he got the truck charging, starting and fuel solenoid harness had already been cut up, the starter relay bracket was hanging down, the GP controller was pulled out and the STE-ICE connector was hanging. The steering column was disassembled too. The warning light connectors for both alts were still in tact, so those were taped off and tied back. The suppressor off the right alt was gone. All I did was trim the wires back to the harness (the rest of the way), and ensure none were energized.

I see your in Colorado Springs. Is the truck you did the conversion on the one we are talking about in this thread?

This is the truck in question

And just an FYI, You do need to put a location in your user profile. Part of the site rules.

Done! Thanks!

Please clarify something. You said it was a single wire alternator, but the diagrams he provided show a two wire setup. Can you tell us which it is? and if it is a single wire where is it hooked too?

Good looking truck by the way.

Good point! The alternator is a 24V 10SI single wire. It has one wire coming off the positive stud going to the positive terminal board. Now, here is where you just turned on the light bulb. I DID install a ground strap from where the housing would have mounted off the back in a different application (10mm bolt) for support. Now, the housing is already grounded through the brackets, so I don't think that this could be causing the drain on the batteries. I just looked at the schematic and realized that I left the warning light connectors shown as hooked up. This is NOT the case! They are not connected. The provision is there for a plug-in, but it is blocked off, so I didn't attempt to remove the plug.

Last time I talked to Kenz5380, his Volt meter was indicating a draw on the batteries when the truck was off... This was right before it went crazy and died completely. I am planning to go up there and Troubleshoot it soon (hopefully). An additional note is that it still had the draw with the 12V distribution block disconnected. BUT, I did some research tonight and found that the GP resistors come off the 24V PTB... that is the one place I did not tell him to test!

 

[Warthog]

Since the truck started out with hacked up wiring, finding the problem will be a hit and miss exercise.

First lets rule out a problem with the alternator.

Charge the batteries, disconnect the "feed" wire to the alternator and let it sit over night.

We are doing this since you don't have an ampmeter yet. If the drain is still there we have ruled out this item and we will need to continue the search.

 

[kenz5380]

I know it has been a while since I posted this originally, but I've tried a bunch of things to fix this problem and I still don't know for sure what is going on.
Does anyone know if it is possible that if I had one or more bad glow plugs they could drain my battery very quickly when the glow plug module is activated? I just can not figure out how I have 0 amps/volts drawing on the battery when the truck is off, but I start with fully charged batteries and 2-3 starts later my batteries are dead. I load tested the batteries and they are good. I removed the GP control card and things got way better, as it had the GPs on all the time, but it is still going dead every 2-3 starts.

 

[mistaken1]

Did you have the starter tested? Perhaps it is damaged and drawing way too much current even though it still turns the engine over.

 

[jbclassix]

Also, the glow plug resistors had 0.0 Ohms across them and we had 24V at the relay... The relay had constant ground to the coil side even with the control module removed. According to the schematic, the ground is the signal to the relay, it gets 12V constant from the ignition. I may be wrong on this though, I am using a TM without the updates, so I was already wrong on the small orange wire on the relay.

 

[kenz5380]

So I bought a new GPM from antennaclimber, I'm going to get a new set of GPs and a new GP relay. I've converted the system over to 12 volts and eliminated the resistor. While I'm waiting on installing all of that I need to figure out why the GP relay still has a constant ground. I'm considering looking around for a new engine wiring harness, if one is available. I also need to investigate whether the starter, or some other portion of the system is drawing too much power. I really don't know exactly how I'm going to do all of this or where I'm going to start, but I'll figure something out I guess. My starter is brand new so I really hope it isn't that. Although, if it is the starter I may just take the whole truck to 12 volts as that is the only 24 v system I have left. We'll see...

 

[kenz5380]

I've got a list of modifications that may or may not be the cause of some of my troubled, but I'm thinking that I have a short somewhere in the starter circuit or a bad starter. I'll go through the problem I'm having and then list the modifications that I've done in case one of them might be the source of the trouble.
THE PROBLEM- My M1008 will not reliably start every time I turn the key. If I fully charge both batteries I can get a hand full of starts out of it before they are both dead. Sometimes more sometimes less. For instance, yesterday I started the truck, just barely, and drove about 4 miles to get fuel. I shut it down to gas it up and then it didn't have enough juice to engage even the starter relay (I could hear it clacking under the dash). Some days I can start it up and run for a half a day starting and stopping all the time, other days its not the case. The thing I can't figure out is that when I am running my volt meter is right where it needs to be , but when I shut it down it immediately drops into the yellow. If I leave it over night it will sometimes be dead in the morning, sometimes not. I put an amp meter between the negative battery terminal and the neg battery post and it reads nothing while the truck is off so I don't think it has a draw on the battery while the truck is off.
THE MODS- I bought the truck with no alternators so I used a 24v one I had that is a 24v/50amp single wire unit. It is hooked into the 24v junction block on the truck and reads 26v while the truck is running.
Doghead starter relay mod
AC60G Glow plugs
Replacement glow plug relay
Glow plug controller card from antennaclimber
After these mods I have had no trouble with the GP system staying on as it used to do