M998 civilian alternator not charging - new Delco installed (updated)

[mountaindogsix]

Gents,

I have had the typical electrical issues with my 1989 M998 for about 18 months. I am running a robust stereo and accessory package. Here is where I'm at currently. I had a parasitic draw that I think has been corrected. Vehicle stays on a NOCO trickle all year long.

Drove her all day Sunday, stopped to grab food...dead battery. Got it working, drove home and it no longer started. Corrected a wiring issue and had it towed to a garage to finally fix the issue. They got it running and have not had the draw since. However the new alt will not charge. It stays at 24 volts. A new alt has been ordered to swap out. What else should we be looking at? Any suggestions and links to parts if necessary, would be great. You guys have never let me down in the past. Let me know if there is any more info I can provide. Thanks

Two Optima batteries - fully charged
New Delco alternator installed - will not maintain a charge. Replaced old Delco (no damage visible)

 

[Action]

Delco? Have you tried the correct alternator / generator?

 

[TOBASH]

These are not H1 units, so how did your vehicle ever get a Delco?

I would go back to a military unit. Isn't 86HUMV in Texas now? He can help you out.

EDIT - I see you are a new member. WELCOME to the fun and games! Please post pics of your rig. Please post pics of your engine bay.

Please post the stereo pics and what you did to sound deaden the truck to allow for a stereo.

 

[juanprado]

Need more info.

Which delco alt and how is it wired? Pics might help.

How are you running your 12v accessories? Battery equalizer or 12/24 converter?

Have the batteries been load tested, not just charged?

 

[mountaindogsix]

Need more info.

Which delco alt and how is it wired? Pics might help.

How are you running your 12v accessories? Battery equalizer or 12/24 converter?

Have the batteries been load tested, not just charged?

The truck had the Delco 21SI installed and we switched that out for a new one, same model, as I went through the possible issues. There are other threads on using that alt in these trucks for the other folks wondering about that above. That alt showed no damage but I wanted to begin to eliminate issues as we went. The truck also has an alarm system. It should not be interfering with anything but I'm trying to mention as many things as possible to paint a clear picture.

As far as the accessories , they are running straight from the batteries. If either option mentioned above would work let me know. I have had the truck in my local audio store numerous times and have asked them to fix/suggest whatever a better way to ensure the batteries don't die or drain. I saw the threads with the step down converters. Whos would u suggest? I saw vanner van guard and the pyle...big price difference. I have a light bar/sub/speakers/back up camera/ radio head unit

The mechanic has load tested the batteries. They sat all weekend and she fired right up on Monday as they began work...they have not had her on the trickle and there have been no issues.

I'll supply pics shortly, I was waiting on the mechanic to shoot them to me.

 

[mountaindogsix]

These are not H1 units, so how did your vehicle ever get a Delco?

I would go back to a military unit. Isn't 86HUMV in Texas now? He can help you out.

EDIT - I see you are a new member. WELCOME to the fun and games! Please post pics of your rig. Please post pics of your engine bay.

Please post the stereo pics and what you did to sound deaden the truck to allow for a stereo.

This is what I did.

I bought a 5X5 piece of wood we got at McCoy's lumber. Neither Lowes or HD had that off the shelf. I dynamatted one complete side and then used the extra at the top where my overhead speakers are mounted over the drive and passenger seats. The speakers are in a Plan B Humvee mount that they used to sell. I then covered the entire board with a thin rug I got from Lowes. I used 3M adhesive and small nails to affix the rug. I removed the soft top and metal screwed the board to roof frame hard points and replaced the soft top. Its extremely tight but has helped both with sound and flapping. I used some of the remaining rug and dynamat on the middle of the truck and under the floor mats. I have a touch screen Rockford-Fosgate head unit./a Phoenix Gold sub 1500 watts...I can't remember the speakers off hand. I have amps running to all of those and the sub along with a capacitor. The equipment is all wired with Marine stereo wiring. Its sounds great and is beyond loud but its why I have had issues. If she stays on the trickle I'm good. This was a recent problem but I had no issues all summer and winter of this year. Oddly when I had my most recent problem...the system worked fine.

 

[Action]

Please post a pic of your battery compartment.

 

[mountaindogsix]

Please post a pic of your battery compartment.

I'm going to drive up and take a few pics. I appreciate the help to all.....the battery compartment is a shitshow .....no judging

 

[mountaindogsix]

New alt coming in tommorrow.

 

[Action]

New alt coming in tommorrow.

WOW !

The delco-remy 21si looks to be 50 / 63 amp. Uh., what is the total draw from all of the stuff in your truck and the truck?

 

[mountaindogsix]

WOW !

The delco-remy 21si looks to be 50 / 63 amp. Uh., what is the total draw from all of the stuff in your truck and the truck?

I don't know.....would u suggest a bigger alternator ?

 

[Coug]

I don't know.....would u suggest a bigger alternator ?

The early HMMWV came with a 60 amp. Then came 100 amp. The 200 amp is standard in all newer HMMWVs (since mid 90's I believe), and there is even a 400 amp for some setups.
50 amp will likely work, but will take a while to recover the batteries if they get low, where a larger one will do it in shorter time, while still being able to run all of your toys.

 

[Action]

If he honks the horn with all that stuff on, it will strain the alternator. The early 60amp HMMWVs did not have all that stuff stuck in there that didn't belong.

I personally would get this one...

 

[sue]

Gents,

I have had the typical electrical issues with my 1989 M998 for about 18 months. I am running a robust stereo and accessory package. Here is where I'm at currently. I had a parasitic draw that I think has been corrected. Vehicle stays on a NOCO trickle all year long.

Drove her all day Sunday, stopped to grab food...dead battery. Got it working, drove home and it no longer started. Corrected a wiring issue and had it towed to a garage to finally fix the issue. They got it running and have not had the draw since. However the new alt will not charge. It stays at 24 volts. A new alt has been ordered to swap out. What else should we be looking at? Any suggestions and links to parts if necessary, would be great. You guys have never let me down in the past. Let me know if there is any more info I can provide. Thanks

Two Optima batteries - fully charged
New Delco alternator installed - will not maintain a charge. Replaced old Delco (no damage visible)

Just get a 24 (2 volt one wire alternator, with the expected amp
Draw, easy pesy

 

[mountaindogsix]

The early HMMWV came with a 60 amp. Then came 100 amp. The 200 amp is standard in all newer HMMWVs (since mid 90's I believe), and there is even a 400 amp for some setups.
50 amp will likely work, but will take a while to recover the batteries if they get low, where a larger one will do it in shorter time, while still being able to run all of your toys.

This is a recent issue. I should know more once we swap out the alternators. Thanks for the replies....any insight is appreciated.

 

[TOBASH]

This could be anything from an insufficient alternator to a belt that gets loose when warmed up and then starts slipping. Couple that with a high amp draw stereo and mismatched batteries and there she is.

 

[Action]

Isn't it advised to have matching batteries?

[quote[[/quote]

EDIT: TOBASH beat me to that point.

I used to install car stereos and systems in my driveway in the 1990's. I would never have sent anything out looking like that. Is this at a professional shop? or just a buddies place?

 

[mountaindogsix]

Pro......

I'm waiting on a replacement for the battery

 

[NDT]

Dude all your problems stem from not having a 24/12 converter. Can’t hang 30 amps of 12 volt loads on one battery and expect the battery to get charged through the other one.

 

[Action]

Dude all your problems stem from not having a 24/12 converter. Can’t hang 30 amps of 12 volt loads on one battery and expect the battery to get charged through the other one.

Looks like there are 12 volt loads attached to both batteries !