1987 M998 Battery Generator Gauge Bouncing in Red, Stays in Red while driving for few minutes

[Coug]

yes, you definitely want a converter. There have been people that ran loads off of just one battery in the past that ended up having catastrophic battery failures as a result of the load imbalance.
If the guy installing the sound system thinks you can just hook to one battery in a 24V system that doesn't have a dual voltage type charging system, then you need to find someone that understands electrical systems to do the install.

 

[Lit_Armo]

Yes that is a 60A, you also have a GEP engine that is very good!!

Thank you I'll look for the right regulator for this one.

Is the GEP a 6.5L, or is there a 6.2L? I thought mine was 6.2L and what is nice about GEPs? Thanks

 

[Lit_Armo]

yes, you definitely want a converter. There have been people that ran loads off of just one battery in the past that ended up having catastrophic battery failures as a result of the load imbalance.
If the guy installing the sound system thinks you can just hook to one battery in a 24V system that doesn't have a dual voltage type charging system, then you need to find someone that understands electrical systems to do the install.

Yeah I'll bring it back to him, he's not a specialist on Humvees he's just great with sound system things and local in my area. He wanted to put the converter but I had a time crunch, so he didn't put it but I'll bring it back I didn't know it was that important.

 

[Mogman]

Thank you I'll look for the right regulator for this one.

Is the GEP a 6.5L, or is there a 6.2L? I thought mine was 6.2L and what is nice about GEPs? Thanks

It is or should be a 6.5L, AMG bought the rights to the 6.5L when GM quit producing them and made some significant improvements to the engine, they formed the General Engine Products company.

 

[Lit_Armo]

It is or should be a 6.5L, AMG bought the rights to the 6.5L when GM quit producing them and made some significant improvements to the engine, they formed the General Engine Products company.

Thats awesome I didn't know I had a 6.5L, I also have a 3 speed though. So it would be possible in my 87 M998 to have the GEP 6.5L with a 3 Speed? (I use a parking brake, and have D , 1, 2)

 

[Coug]

Yeah I'll bring it back to him, he's not a specialist on Humvees he's just great with sound system things and local in my area. He wanted to put the converter but I had a time crunch, so he didn't put it but I'll bring it back I didn't know it was that important.

For converters, there are plenty of cheap chinese made ones out there, but you'd want to install it with a relay or switch so it turns off when not in use. Or you can buy a good quality one with the relay built in and all you have to do it get it wired to a switched 24V supply, like ignition or fan circuits.
Example:

Orion DC-DC Converters Non-isolated, High power - Victron Energy

Eliminate the need for a high current switch in the input wiring with the remote on/off connector on the Orion DC-DC Converter. Find a dealer near you.

www.victronenergy.com

Thats awesome I didn't know I had a 6.5L, I also have a 3 speed though. So it would be possible in my 87 M998 to have the GEP 6.5L with a 3 Speed? (I use a parking brake, and have D , 1, 2)

Once GM stopped building the 6.2l engine, the military started replacing them during rebuild with a detuned 6.5l. It has the same HP output as the 6.2, but better quality. Then the GEP engine came out after GM discontinued the 6.5, and GEP fixed some of the issues that GM hadn't really cared about (mostly better metalurgy, so less likely to crack the rear cylinders due to heat soak, as the HMMWV cooling sustem isn't the best)
So very common to see a 6.5 with a 3 speed

 

[Mogman]

It looks like someone may have painted over the nomenclature on your alt, I believe the reg you are looking for is a AMA2004AS.
On some alternators it is reported that the outside circumference must be filed down a little bit so the regulator will slip into the back of the alternator.
Also your alternator likely has three leads going to the regulator and the replacement has 4 terminals, you simply do not use the terminal that does not match the leads from the alternator, when you open it up be careful and take several pictures before removing the leads from the old regulator.
Many times the wires are damaged where they connect to the terminals and the tags that have the wire ID is damaged so you need to pay close attention to where all the leads were connected.
THIS is another reason to rebuild the 60A as soon as it starts to act up, the longer you wait the more damage is done to the wiring etc.

For all the reasons above I highly recommend removing the alt and build it on the bench, if all things were perfect you could do it on the truck but it is much more difficult.
I have had pretty good results dealing with these guys and they have notes on where the wires go.

Regulator Assembly For AMA5104UT 60 Amp 28 Volt Alternator, AMA2004AS

Regulator assembly for the Prestolite AMA5104UT / 10929868 and AMA5103UT 60 Amp, 28 Volt alternator used on many Military vehicles. Regulator P/N AMA2004AS. Alternate p/n 35-605, 35-790, 5730138, SAW-11808666. NSN 2920011808666. Made in USA. 2 lb <hr> Notes: <u>Will not fit 10929868...

eriksmilitarysurplus.com

 

[Mogman]

When you get the alt off post a clear picture of the back of the alt.
This will allow us to see what reg you need.
If it has pin connectors instead of spade terminals on the reg then you would need part # AMA1004S this is the early style alt.

 

[Lit_Armo]

It looks like someone may have painted over the nomenclature on your alt, I believe the reg you are looking for is a AMA2004AS.
On some alternators it is reported that the outside circumference must be filed down a little bit so the regulator will slip into the back of the alternator.
Also your alternator likely has three leads going to the regulator and the replacement has 4 terminals, you simply do not use the terminal that does not match the leads from the alternator, when you open it up be careful and take several pictures before removing the leads from the old regulator.
Many times the wires are damaged where they connect to the terminals and the tags that have the wire ID is damaged so you need to pay close attention to where all the leads were connected.
THIS is another reason to rebuild the 60A as soon as it starts to act up, the longer you wait the more damage is done to the wiring etc.

For all the reasons above I highly recommend removing the alt and build it on the bench, if all things were perfect you could do it on the truck but it is much more difficult.
I have had pretty good results dealing with these guys and they have notes on where the wires go.

Regulator Assembly For AMA5104UT 60 Amp 28 Volt Alternator, AMA2004AS

Regulator assembly for the Prestolite AMA5104UT / 10929868 and AMA5103UT 60 Amp, 28 Volt alternator used on many Military vehicles. Regulator P/N AMA2004AS. Alternate p/n 35-605, 35-790, 5730138, SAW-11808666. NSN 2920011808666. Made in USA. 2 lb <hr> Notes: <u>Will not fit 10929868...

eriksmilitarysurplus.com

Thank you I have a picture of the back of the regulator while in the truck, it looks like the same part you sent! If I can do a rebuild on the 60amp it would be great, is it possible to rebuild these locally or it needs a specific shop? And on average what would be the cost? If I bought the regulator and it didn't fix my problem, would I save money by taking my regulator and having the alt rebuilt with it?

My plan is to change the regulator on my 60amp alternator, or rebuild the whole alternator, and install the 24v/12v Orion 70amp or 100amp converter for my sound system (depending if I need more than 70amps).