The Once And For All On Batteries...

[GTR0419]

...at least for me.

I know the battery discussion has been done many times and it's quite obvious that you can operate without spending on 6t's. But my question here is, is it the best option? In other words, there is a part of me that thinks the vehicle should be set up as it was engineered. Why? Because I often over think things.

When I bought my M1078 six years ago, it didn't have batteries. Not wanting to spend big money right out of the gate, I installed four 34 series batteries. It is now time to replace them. While it would be easy to say the 34's worked fine for six years, the rig has seen very little use. It mostly just sat in the parking lot of my warehouse. I'm going to be freshening the big girl up this spring and adding A/C with the probability of selling it this year. I've also discovered that the 6tl's can be had for about $200 now.

So, what would you do? $900 to return it back to an original configuration or $500 to stick with the 34s? Is it really just a matter of "wasting" $400? No doubt there are scenarios where you would go big. But outside of originality, is there any reason for the hobbyist to keep all that juice on board?

 

[Karl kostman]

One thing to remember contracts like for batteries generally go to the lowest bidder who can meet the requirements specified. What does this mean to you is that you can put any decent quality battery in your truck and it will work fine, as you have already proven! The Military generally puts 4 batteries in the trucks because it gives it the best chance of starting IN ALL CONDITIONS, Now I know I dont live in an area that has ALL CONDITIONS so I only have one out of 7 trucks that has all 4 batteries in it, everything other one has only 2. My trucks are not run over the winter and in the summer all my trucks start very good and I have no need for all the reserve cranking power. Its pretty specific to you needs I stopped buying 6tls a long time ago and have never regretted it! Think about this remember when all the M series trucks came with NDT type tires supposed to be the best tire for many different types of terrain as it turns out they were only marginal at best for many different types of terrain! Just because it done one way sure does not mean that its the best way to fill your needs!
Dont be afraid to try new things!

 

[GTR0419]

One thing to remember contracts like for batteries generally go to the lowest bidder who can meet the requirements specified. What does this mean to you is that you can put any decent quality battery in your truck and it will work fine, as you have already proven! The Military generally puts 4 batteries in the trucks because it gives it the best chance of starting IN ALL CONDITIONS, Now I know I dont live in an area that has ALL CONDITIONS so I only have one out of 7 trucks that has all 4 batteries in it, everything other one has only 2. My trucks are not run over the winter and in the summer all my trucks start very good and I have no need for all the reserve cranking power. Its pretty specific to you needs I stopped buying 6tls a long time ago and have never regretted it! Think about this remember when all the M series trucks came with NDT type tires supposed to be the best tire for many different types of terrain as it turns out they were only marginal at best for many different types of terrain! Just because it done one way sure does not mean that its the best way to fill your needs!
Dont be afraid to try new things!

So, maybe I shouldn't do 4 batteries at all this time? I think I went with four last time because this was my first MTV and didn't know the platform.

 

[Third From Texas]

Go dual unless you are in N. Maine, Alaska, Montana, etc. In GA you don't need four.

Set up for dual. You can always swap back.

All three of my trucks were converted to two (you can even use the existing cables).

*not my image, but it's what I used.

 

[Bill Nutting]

The last time my M934 had four batteries they were all dead and beyond taking a charge. I run two batteries. My truck sits way more than it should. I installed a 24 volt battery tender and leave it plugged in all the time. I live in Michigan so I installed a block heater. When the temp goes below 40, I plug in the block heater for 20 minuets or so. The trucks easy on two batteries every time. If I were being shot at I might want to be able to crank the thing hard till it started...

 

[GTR0419]

Go dual unless you are in N. Maine, Alaska, Montana, etc. In GA you don't need four.

Set up for dual. You can always swap back.

All three of my trucks were converted to two (you can even use the existing cables).

*not my image, but it's what I used.


View attachment 824932

What size are you running? I can't remember why I went with 34s.

 

[Recovry4x4]

I really like group 31 truck batteries. I have 2 in my CUCV, 2 in my dump truck and my son has 2 in his tanker truck.

 

[Awesomeness]

One thing to remember contracts like for batteries generally go to the lowest bidder who can meet the requirements specified. What does this mean to you is that you can put any decent quality battery in your truck and it will work fine, as you have already proven!

Well, this is true, but also a completely misleading statement the way it's being phrased. The military specifications for stuff are usually quite extreme, so typically civilians stuff is not even close. There is a reason the mil-spec version of things costs several times more.

The flip side, and the reason the myth that civilian and military grade things are similar, is that most civilians are not really doing anything difficult with their surplus equipment. So even a cheap Chinese substitution will probably "work", because it doesn't need to meet such a high threshold.

On to batteries... the military batteries are AGM batteries, which are pretty much better in every way. More current, more energy capacity, better vibration resistance, better recovery from over discharging. They also last 2-3x as long as regular lead-acid batteries! So the fact that they cost more isn't as bad as it sounds, since you'll be buying 2-3x less of them.

My recommendation is to just use the 6TL batteries it was designed for, and enjoy knowing you have their full capability. They should last long enough to pay for the greater up-front cost.

 

[GTR0419]

Well, this is true, but also a completely misleading statement the way it's being phrased. The military specifications for stuff are usually quite extreme, so typically civilians stuff is not even close. There is a reason the mil-spec version of things costs several times more.

The flip side, and the reason the myth that civilian and military grade things are similar, is that most civilians are not really doing anything difficult with their surplus equipment. So even a cheap Chinese substitution will probably "work", because it doesn't need to meet such a high threshold.

On to batteries... the military batteries are AGM batteries, which are pretty much better in every way. More current, more energy capacity, better vibration resistance, better recovery from over discharging. They also last 2-3x as long as regular lead-acid batteries! So the fact that they cost more isn't as bad as it sounds, since you'll be buying 2-3x less of them.

My recommendation is to just use the 6TL batteries it was designed for, and enjoy knowing you have their full capability. They should last long enough to pay for the greater up-front cost.

How about going with two 6TLs?

 

[Ronmar]

It wasn’t engineered, it was built to a milspec... IE: what is the cheapest way we can build this thing and still get uncle sugar to sign off on it...

By any common automotive standard, the 4EA 6TL battery bank is more than twice as large as it should be for the alternator, or the 100A combined output Neihoff alternator is less than 1/2 as large as it should be for the size battery bank used... it is not a real problem IF the batteries are maintained at a full state of charge. But if the charge level is allowed to droop(setting more than running in your parking lot), the alt doesn’t get enough time to recharge that massive bank, which takes time, so the batts are in a constant partial charge which shortens lifespan.

It takes 25% of the AH rating in amps out of the alt to meet the acceptance charge requirement of standard lead acid batteries(AGM’s need 45%) the 6TL total is 240AH, so 60A needed. You only have 50A available on either 12 or 24V output, and once you factor in other electrical loads, like the 12v lighting load of 22-28A(33A on a M1079), once batteries get discharged, you are left with under-charged batteries and alternators that run in a constant state of overload...

This is evidenced by the number of alt and battery issues these trucks experience. In the automotive industry, this is the kind of engineering error that leads to class action lawsuits and recalls. It is of course passable in the land of milspec.

It is also evidenced by the changes made to the follow-on vehicle models. The A1 got the LBCD added, a device that senses alternator load via the regulator F- terminal and disconnects the battery bank from the main line and alternator, and puts it on a trickle charge to keep the alt alive to power the truck. It also tells the operator there is a problem. The A1R got a 260A alternator, which is the size alt they should have used for this bank in the beginning...

In the power equipment cat manufacturers with the 3116/3126 engine, they spec a pair of group 31 batteries(100AH) in series with a 52A alternator(peak charging load is only 50% of alt output)...

I think all these trucks have a 12V vampire load from the transmission so long periods of setting unbalances the bank and the 12V side having most of the load, leads to a higher instance of issues with the 0-12v batteries... unless you drive this thing like your other vehicles(several times a week) it should have a 24V tender and a small battery equalizer attached to the bank to keep it floated to a safe long term voltage to maximize battery life...

Your four group 34’s at 55AH(110AH Total) are not all that different from what cat specs, as long as they are not the AGM version... What probably got you a short 6 year life was inactivity and partial charge.

I run a pair of group 31’s, and group 27’s would be fine also IMO. A pair of 6TL’s wouldn’t be horrible either, as long as they are not AGM’s... group 31’s and 27’s are commonly available for around $100 each though...

 

[GTR0419]

Interestingly, doing a little research, I have found that the 34 series batteries, from Optima Reds to the store brands, have more CCAs than 6tls. The 6tls shine (big time!) in reserve capacity.

 

[GTR0419]

It wasn’t engineered, it was built to a milspec... IE: what is the cheapest way we can build this thing and still get uncle sugar to sign off on it...

By any common automotive standard, the 4EA 6TL battery bank is more than twice as large as it should be for the alternator, or the 100A combined output Neihoff alternator is less than 1/2 as large as it should be for the size battery bank used... it is not a real problem IF the batteries are maintained at a full state of charge. But if the charge level is allowed to droop(setting more than running in your parking lot), the alt doesn’t get enough time to recharge that massive bank, which takes time, so the batts are in a constant partial charge which shortens lifespan.

It takes 25% of the AH rating in amps out of the alt to meet the acceptance charge requirement of standard lead acid batteries(AGM’s need 45%) the 6TL total is 240AH, so 60A needed. You only have 50A available on either 12 or 24V output, and once you factor in other electrical loads, like the 12v lighting load of 22-28A(33A on a M1079), once batteries get discharged, you are left with under-charged batteries and alternators that run in a constant state of overload...

This is evidenced by the number of alt and battery issues these trucks experience. In the automotive industry, this is the kind of engineering error that leads to class action lawsuits and recalls. It is of course passable in the land of milspec.

It is also evidenced by the changes made to the follow-on vehicle models. The A1 got the LBCD added, a device that senses alternator load via the regulator F- terminal and disconnects the battery bank from the main line and alternator, and puts it on a trickle charge to keep the alt alive to power the truck. It also tells the operator there is a problem. The A1R got a 260A alternator, which is the size alt they should have used for this bank in the beginning...

In the power equipment cat manufacturers with the 3116/3126 engine, they spec a pair of group 31 batteries(100AH) in series with a 52A alternator...

I think all these trucks have a 12V vampire load from the transmission so long periods of setting unbalances the bank and the 12V side having most of the load, leads to a higher instance of issues with the 0-12v batteries... unless you drive this thing like your other vehicles(several times a week) it should have a 24V tender and a small battery equalizer attached to the bank to keep it floated to a safe long term voltage to maximize battery life...

Your four group 34’s at 55AH(110AH Total) are not all that different from what cat specs, as long as they are not the AGM version... What probably got you a short 6 year life was inactivity and partial charge.

I run a pair of group 31’s, and group 27’s would be fine also IMO. A pair of 6TL’s wouldn’t be horrible either, as long as they are not AGM’s... group 31’s and 27’s are commonly available for around $100 each though...

Yes. All of this. I have no doubt the batteries suffered. I had to charge them a couple times. I was not aware of the trans draw or alternator issue, but it makes sense. I have purchased a 24v solar charger to install.

Why are AGMs a problem?

 

[Third From Texas]

What size are you running? I can't remember why I went with 34s.

Dual 6TLs on all my trucks.

Mostly because I like the OEM tie down system and didn't want to hack up the top in case I reverted back to four (never know when we *all* may be at war or have to bug out to nasty cold places, etc). But I've seen people retrofit all sorts of sizes. There are a size or two that will fit in the OEM holder, but be advised that one company may add different handles or strap slots that suddenly make their battery not fit. So if you can, see one fit before purchasing two (or four).

There are several threads here and on the LMTV FaceBook page (FB blows goats with their censorship, fyi). Look for ideas. Decide if you want to chop your box lid or make a custom tie down, etc. If you are willing to be a bit creative, it opens more options (and some guys have made some slick battery box solutions). Or if you want to stay OEM. Then work from there.

And AGM's (or gels) are awesome especially if you are hammering around off road and don't want to risk banging the plates around. I don't have that kind of money to spend at the moment (I'd love to try big-arse Optimas or something). But I'm poor, so NAPA/Interstate 6TL's for me.

 

[GTR0419]

Yes. All of this. I have no doubt the batteries suffered. I had to charge them a couple times. I was not aware of the trans draw or alternator issue, but it makes sense. I have purchased a 24v solar charger to install.

Why are AGMs a problem?

Never mind. I see it. It's the AH recharge requirement.

 

[GTR0419]

I remember why I went 34. Optima made an adapter plate for converting 6tl to a Red Top 34. I just went with the 34 from there. That's science, right?

 

[Third From Texas]

Never mind. I see it. It's the AH recharge requirement.

As Ronmar said, if all our trucks had 260a alts more things become viable.

 

[Ronmar]

I remember why I went 34. Optima made an adapter plate for converting 6tl to a Red Top 34. I just went with the 34 from there. That's science, right?

A batteries current output capacity is determined by it’s ability to convert chemical to electrical energy. More plate surface area = more current capacity/CCA
Absorbed Glass Mat batteries accomplish the chemical to electrical transfer more efficiently than plain plates so for a given size battery they can deliver significantly higher peak current. but because of this efficiency they also want more charge current and load the alternator like a battery twice their size.

Battery storage capacity(AH) is a factor of electrolyte volume, so directly relates to physical size.

if yours are AGM‘s then you basically built an equivalent alternator load to four 6TL’s, but with 1/2 the overall storage capacity So they would reach full charge Twice as fast as four 6TL’s would.

AGM’s are not a problem, you just have to size them or the charging source accordingly. their biggest use is in motorsports and aviation as you can get a given peak current output at a much lighter weight. They are also typically more vibration resistant... Not much advantage using them on an LMTV IMO...

 

[Awesomeness]

I keep my truck plugged into a NOCO Gen4 charger, when not in use.

 

[tennmogger]

Great info! Couple of additions: for any vehicle that sits for any length of time beyond a few days, 2 batteries may actually be better. Batteries in parallel are never equal. The worse one will load the better one, and both discharge more quickly. All the bad batteries out of the military is a good proof/example.

Second, don't ever try to start a vehicle if the batteries are low. Charge them first. Why? Because if one cell is lower than the others (always the situation!) then that cell discharges to zero first. Once it is dead, the flowing current as you try to start the vehicle, and the fact the battery has its positive to nearest neg, and its neg to nearest pos, it will charge in reverse polarity. Reverse charging a cell kills it.

 

[GTR0419]

Go dual unless you are in N. Maine, Alaska, Montana, etc. In GA you don't need four.

Set up for dual. You can always swap back.

All three of my trucks were converted to two (you can even use the existing cables).

*not my image, but it's what I used.


View attachment 824932

So, I'm going to go with two batteries. Four just doesn't seem to make any sense; financially or otherwise.

How do I identify the 24V vs 12V cable? Maybe it will be obvious when I look at it, but the only cables I recall being obvious are the NATO plug wires.