LMTV CTIS Question

[Hobie_rat]

Realistically, they probably aren't very easy to kill. Military electronics have to meet extremely rigorous specifications (e.g. temp, overvoltage, polarity, EMP, EMI, etc.). But we have a member ( @Stellaevil who I haven't seen in a while), that worked at Spicer, and said that there are capacitors(?) inside that fail after many years, and the potting makes them irreparable. Repairability just wasn't something the government cared about, compared to being vibration and water proof.

 

[Mullaney]

Here are the current readings from all 4 batteries with the engine on and off

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What about all 4 batteries as individual batteries?
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[Ronmar]

They may not be easy to kill, but they do appear to have a fairly high failure rate

IRT your battery voltages, they are OK, but they also illustrate one of the biggest issues with the LMTV. Depending on the battery type those resting voltages indicate a range of 70-85% state of charge. You are not running the vehicle enough to fully charge the batteries, and the small 12v vampire load that slowly siphons away power on the outer pair of batteries Is evident by the lower voltage there. The 6TL, 4 battery bank is grossly oversized for the 100A alt. Even more so if they are AGM’s(they want nearly twice the charge current of normal wet cells). The large size means they take a long time to charge, so unless you run a lot, they just never make it. this also means the alt is running at full load most of the time you are running. Your running voltages being .1-.2v low possibly indicate this to me Also(Should be 14.1/28.2V).

Low state of charge is the largest killer of batteries there is. Failing batteries keep the alt in a constant state of overload…

Do yourself and that $2500 alternator a favor and drop to 2 batteries(one inner and one outer). That will get you a lot closer to a good alt/battery relationship. Cat specced a pair of group 31 batteries for these engines…

Add a maintenance charger and a small battery balancer to keep the batteries nearer 100% SOC and they will last a lot longer…

Good Luck!

 

[Ronmar]

.
What about all 4 batteries as individual batteries?
.

I got the impression that the inner 2 were the same(12.5) and the outer two were also the same(12.4). Being wired in parallel, that is not unexpected…

 

[Hobie_rat]

.
What about all 4 batteries as individual batteries?
.
[/QUOTE
Thanks for asking I did include them, each (ea) one of the 2 back batteries is 12.5v apiece with the ignition off and 12.4v apiece on the 2 front batteries and 14.0v each one of the back batteries and 13.9 each one on the 2 front either the ignition on

 

[Hobie_rat]

I disconnected the wires before testing. I’ve heard this is an effect of how they are wired when charging

 

[Hobie_rat]

They may not be easy to kill, but they do appear to have a fairly high failure rate

IRT your battery voltages, they are OK, but they also illustrate one of the biggest issues with the LMTV. Depending on the battery type those resting voltages indicate a range of 70-85% state of charge. You are not running the vehicle enough to fully charge the batteries, and the small 12v vampire load that slowly siphons away power on the outer pair of batteries Is evident by the lower voltage there. The 6TL, 4 battery bank is grossly oversized for the 100A alt. Even more so if they are AGM’s(they want nearly twice the charge current of normal wet cells). The large size means they take a long time to charge, so unless you run a lot, they just never make it. this also means the alt is running at full load most of the time you are running. Your running voltages being .1-.2v low possibly indicate this to me Also(Should be 14.1/28.2V).

Low state of charge is the largest killer of batteries there is. Failing batteries keep the alt in a constant state of overload…

Do yourself and that $2500 alternator a favor and drop to 2 batteries(one inner and one outer). That will get you a lot closer to a good alt/battery relationship. Cat specced a pair of group 31 batteries for these engines…

Add a maintenance charger and a small battery balancer to keep the batteries nearer 100% SOC and they will last a lot longer…

Good Luck!

Thank you very much. I charge the batteries periodically. Run time is still limited because I’m waiting for the title. In the mean time I’m doing what maintenance I can do when it’s time to be inspected I won’t have any issues. I’ll remove 2 of the batteries and see if that helps with changing and look into installing a balancing device

 

[Hobie_rat]

Thank you very much. I charge the batteries periodically. Run time is still limited because I’m waiting for the title. In the mean time I’m doing what maintenance I can do when it’s time to be inspected I won’t have any issues. I’ll remove 2 of the batteries and see if that helps with changing and look into installing a balancing device

I’ve noticed an air leak has developed in the air system av the the service tanks are empty in the morning when they were showed 120psi the night before

 

[Mullaney]

I’ve noticed an air leak has developed in the air system av the the service tanks are empty in the morning when they were showed 120psi the night before

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Crank the truck. Air to full, then off the truck. Maybe you can hear it or maybe note. Get a spray bottle and use dish soap and warm water. Spray everything in sight that looks like an air hose or air line. Start up front with the glad hands at the bumper. Get the lines behind the grille too. Under the truck. Start at the 3 tanks on the drivers side. Spray the valves, spray the hose (line) connections on the tanks. ESPECIALLY spray an air hose (for inflating tires) if it happens to be on or near the tanks. Follow the air lines to both axles.

 

[Ronmar]

What Mullaney said! I start with my ears, then my hands, then bubble mix. I would add check the glad-hands and normal vents(right under heater behind grill, bottom of relays and qr valve). Also don't forget the park and trailer plumbing in the dash. The seals on the push-pull control on the valves is a common leak down spot…

 

[Hobie_rat]

.
Crank the truck. Air to full, then off the truck. Maybe you can hear it or maybe note. Get a spray bottle and use dish soap and warm water. Spray everything in sight that looks like an air hose or air line. Start up front with the glad hands at the bumper. Get the lines behind the grille too. Under the truck. Start at the 3 tanks on the drivers side. Spray the valves, spray the hose (line) connections on the tanks. ESPECIALLY spray an air hose (for inflating tires) if it happens to be on or near the tanks. Follow the air lines to both axles.

Will do! I saw the glad hand seal are looking a little rough. Definitely start by replacing those and climb around to look for leaks. Both cages are broken on the driver side. Had to tell the guys towing it back to my place to air up the tanks to release the parking brakes

 

[Third From Texas]

Do yourself and that $2500 alternator a favor and drop to 2 batteries(one inner and one outer). That will get you a lot closer to a good alt/battery relationship. Cat specced a pair of group 31 batteries for these engines…

Add a maintenance charger and a small battery balancer to keep the batteries nearer 100% SOC and they will last a lot longer…

So much THIS ^

Even with my A1R and 260a alt, I'm only running dual batteries (the other pair is for the habitat and charge via shore power).

Now if your truck is a daily driver operating above the arctic circle, then the extra cranking amps are needed. But S&S really screwed the design tossing 100a alts into the mix.

 

[Hobie_rat]

So much THIS ^

Even with my A1R and 260a alt, I'm only running dual batteries (the other pair is for the habitat and charge via shore power).

Now if your truck is a daily driver operating above the arctic circle, then the extra cranking amps are needed. But S&S really screwed the design tossing 100a alts into the mix.

Appreciate. Will look into reconfiguring the battery box. Would have saved $500 in batteries if I’d found you guys sooner. Thanks for all the tips and info

 

[Third From Texas]

Appreciate. Will look into reconfiguring the battery box. Would have saved $500 in batteries if I’d found you guys sooner. Thanks for all the tips and info

It's super simple, really.

 

[Hobie_rat]

It's super simple, really.

View attachment 875124

Super simple, no lie. I would like to install a master disconnect switch, though

 

[Ronmar]

Super simple, no lie. I would like to install a master disconnect switch, though

The simplest way is to add a high current switch on that ground lead. This will stop the truck from drawing any current(and kill that 12v vampire). It will NOT however remove the difference in potential between 12 and 24V, so you can still run into issues when working on the truck electrical, like say wrenching on the alternator as you will still see 12V across the 12-24 terminals. So you should still lift battery leads when performing electrical maintenance.

 

[Hobie_rat]

The simplest way is to add a high current switch on that ground lead. This will stop the truck from drawing any current(and kill that 12v vampire). It will NOT however remove the difference in potential between 12 and 24V, so you can still run into issues when working on the truck electrical, like say wrenching on the alternator as you will still see 12V across the 12-24 terminals. So you should still lift battery leads when performing electrical maintenance.

Kk so remove 1 front & back battery and add a “kill” switch (I’ve been looking at this one ) to the neg side. I believe the neg cable coming from the batteries goes to the charging port, towards the back, outside of the box. Would you recommend making the interrupt there, between the charging port and the neg post?

 

[Ronmar]

Kk so remove 1 front & back battery and add a “kill” switch (I’ve been looking at this one ) to the neg side. I believe the neg cable coming from the batteries goes to the charging port, towards the back, outside of the box. Would you recommend making the interrupt there, between the charging port and the neg post?

There are 2 neg leads attached to the battery. One goes to the nato port, the other goes to the starter negative. It is the one that goes toward the starter that you want to interrupt. I don’t know the specs on that switch you showed. Whatever switch you choose it needs to be able to handle at least 500A for short durations. Blue sea systems makes some nice ones, reasonably priced and decent quality.

 

[Hobie_rat]

There are 2 neg leads attached to the battery. One goes to the nato port, the other goes to the starter negative. It is the one that goes toward the starter that you want to interrupt. I don’t know the specs on that switch you showed. Whatever switch you choose it needs to be able to handle at least 500A for short durations. Blue sea systems makes some nice ones, reasonably priced and decent quality.

Thanks. It looks like a marine switch. Ah! Blue Sea. Makes sense. That’s where I‘be seen them, at West Marine Products

 

[Hobie_rat]

Thank you very much. I charge the batteries periodically. Run time is still limited because I’m waiting for the title. In the mean time I’m doing what maintenance I can do when it’s time to be inspected I won’t have any issues. I’ll remove 2 of the batteries and see if that helps with changing and look into installing a balancing device

Removed two batteries and now while the engine is run at idle and at 1500rpm (no tach just sounds like 1500 definitely less than 200) reading are 14.1v and 28.0v. Trying to find a way to get that extra .2v’s maybe that’s where the balancer comes in to play?