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The Once And For All On Batteries...

chucky

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4 batteries were chosen to meet a particular milspec requirement like being able to set for a month on the Siberian step in wintertime and still be able to crank the engine long enough to start it with no supplemental heat. Un fortunately the person designing the electrical system wasn’t in on this plan and didn’t put an alternator in large enough to comfortably handle this situation. This is the kind of error that recalls and class action law suits are made of out in the real world:) you can very comfortably drop to two batteries in series for 24 and take the 12v out of the middle to feed the 12v circuits. To answer your questions:

1. Only 2 or 4 batteries are used. The alternator is designed to operate as a simple battery balancer and is looking to supply 2 batteries of equal size placed in series.

2. Yes, two 8D’s would be more capacity than two of anything else. Keep in mind that the alt is strained keeping large batteries fully charged. Cat specs a pair of group 31 lead acid wet batts(100AH) for the power equipment that uses these engines. A pair of group 31’s is also a good match for the alternator. A pair of group 31 AGM’s will push the alt over 100% load. As for cranking capacity, my 3116 pulls a brief peak to about 290A when starting to crank, but averages just over 150A when cranking… If I was worried about being able to start when cold, I would take steps to mitigate that instead of oversizing the bank as there are other disadvantages besides alt overload.

No you do not want to mix battery capacities. One will top off faster than the other and then start to overcharge, while the other larger battery may have trouble reaching a full state of charge. AGMs are still lead acid, it is just their internal design gives them a lower internal resistance so they can feed more current and can accept/demand more current(nearly twice as much) when charging for a given size battery compared to a normal wet plate cell design.

You certainly don’t want to mix those different types. This same thing can happen when you have a failing battery in parallel with a good one. The failing battery gets overcharged and gets progressively worse, and the good battery never gets fully charged and quickly joins the other bad one…

Unless you have a 260A A1R alt, 4 discharged wet cells is an overload for the alt, 4 discharged AGM’s is an extreme overload for the standard 100A alt. The oversized bank and its associated problems are where the LBCD came from, to disconnect a dead or damaged battery bank from the alt to keep from cooking it…

What kills lead acid batteries is time spent below a full state of charge. The deeper the discharge below full the faster their life clock ticks away as the sulfation builds up robbing them of plate surface area/capacity. Unless you run these trucks for hours at a time, frequently, or keep a maintenance float charge on them when parked, it is more than likely that the batteries rarely if ever reach a full state of charge. The 12v side also has more electrical load so there is less available power from the alt on that side. The 12v side also has a small vampire load… the combination of oversized batt, undersized alt and low run hours is probably why these trucks have so many battery/alt problems. They changed the charging system design twice, so at least they realized something was wrong. They added the LBCD(monitors alt load and disconnects the batts when it becomes overloaded) on the A1, and finally fitting a 260A alt on the A1R. That alt was pretty-much a necessity as the military introduced the AGM batteries…

if I was wanting more house battery, I would have more house battery and not rely on regularly mixing house and service… But maybe that’s just me…:)
Thanks this explains it better for me ! I m with you i should just add another 8d to the house and the solar just keep them up and try the 2 good agm 6tl in the truck to see how that acts . Good Info !
 

chucky

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OK thanks to Ronmar and TFT I switched over to a 2 6tl truck set up and now i need an electric wizzard to tell me why since i have a 3 good 6tl already sitting there i bring my 12v hot and ground from house to the 3rd battery and i bring the hot and ground from the 12 winch all to the 3rd batt and simply put a 12v jumper from hot post 3rd batt to thr negative on the 24v batt but that is the 12v side of the truck so i could still charge the truck batterys from solar or gen and that 3rd battery take the hit from the 12v winch draw ! In my mind this works i just dont want to waste the 3rd good 6tl if i dont have too THANKS for the helpIMG_1779.JPG
 

Third From Texas

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OK thanks to Ronmar and TFT I switched over to a 2 6tl truck set up and now i need an electric wizzard to tell me why since i have a 3 good 6tl already sitting there i bring my 12v hot and ground from house to the 3rd battery and i bring the hot and ground from the 12 winch all to the 3rd batt and simply put a 12v jumper from hot post 3rd batt to thr negative on the 24v batt but that is the 12v side of the truck so i could still charge the truck batterys from solar or gen and that 3rd battery take the hit from the 12v winch draw ! In my mind this works i just dont want to waste the 3rd good 6tl if i dont have too THANKS for the helpView attachment 854284
Interesting. I've often wondered if you could do this (with two or more batteries making up the 12v side and one dedicated to become the 24v side).

My idea was to prolong the capability to get sucked on by the 12v vampire that lives deep inside the truck. But I've also considered using the space for some house batteries.
 

GeneralDisorder

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With my NAPA commercial account the 7256 is $214.

Given my personal experience is only with the stuff I worked on 20 years ago (gen sets [my 52D MOS], M35's, 800, 900 series trucks and HMMWV's) and my current 2008 A1R with the 260 amp alternator, I would think that two of these would be more appropriate for the 100 amp alternator trucks since that's sufficient to start and run the truck in all but the most insane environments and won't present quite as much load to the 100 amp alternators - which dead batteries were the cause of the upgrade to the 260 amp units on the A1R trucks. To avoid soldiers (the lowest common denominator - not the motorpool guys or the mech's) slaving the truck and then hitting the alt with 4 dead batteries that are essentially a bottomless pit for amperage at that point.
 

Larry Weibert

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Just a couple battery observations. I have delt with a lot of batteries over the years. I have a 2007 Kubota 4240 Tractor and a 2007 Kubota 31HP diesel lawn mower. They sit outside all winter and the lawn mower battery just at the end of this season gave up the ghost. The tractor still works great. I think there is something to be said for the different brands or how there made. We sell batteries and none of them last like the stock ones that came with my Kubota's. Just my observation.
On another note my dad taught me a little trick with my 4 battery trucks but can be used on any terminal. He would have me place a voltmeter between each battery post and the clamp one at a time while he would turn it over. If there was a reading between the post and clamp that terminal needed service. simple but works well.
 

Third From Texas

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With my NAPA commercial account the 7256 is $214.

Given my personal experience is only with the stuff I worked on 20 years ago (gen sets [my 52D MOS], M35's, 800, 900 series trucks and HMMWV's) and my current 2008 A1R with the 260 amp alternator, I would think that two of these would be more appropriate for the 100 amp alternator trucks since that's sufficient to start and run the truck in all but the most insane environments and won't present quite as much load to the 100 amp alternators - which dead batteries were the cause of the upgrade to the 260 amp units on the A1R trucks. To avoid soldiers (the lowest common denominator - not the motorpool guys or the mech's) slaving the truck and then hitting the alt with 4 dead batteries that are essentially a bottomless pit for amperage at that point.
You'd be correct.

The 100amp alt is no match for four 6TLs,Hawkers, etc.

Interestingly, the Niehoff dual voltage do not put out the same amps to both 12v and 24v rails.

100amp = 24v 100amp/12v 60 amp
260 amp = 24v 260amp/ 12v 140amp

So when the 12v gremlins suck on a 100amp truck, it's really only 60 amps pulling it up. Not bad until you repeatedly drain a pair of 6TLs flat. It's eats the alternator alive.

These trucks should have all had the 260 amp alts.

ymmv
 
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Third From Texas

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OK thanks to Ronmar and TFT I switched over to a 2 6tl truck set up and now i need an electric wizzard to tell me why since i have a 3 good 6tl already sitting there i bring my 12v hot and ground from house to the 3rd battery and i bring the hot and ground from the 12 winch all to the 3rd batt and simply put a 12v jumper from hot post 3rd batt to thr negative on the 24v batt but that is the 12v side of the truck so i could still charge the truck batterys from solar or gen and that 3rd battery take the hit from the 12v winch draw ! In my mind this works i just dont want to waste the 3rd good 6tl if i dont have too THANKS for the helpView attachment 854284

I'm no electronics wiz by any means. I've let a LOT of smoke out of things.

How is this really different than OEM (you just delete one battery on the 24v side in your img). The 12v gremlins (always lurking) would stull suck on that second 12v house battery the way you have it drawn?
 

Ronmar

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You might be able to do that, add the 3rd 6tl to the house system. What kinda house batteries are you running? Back to the mismatch battery thing, it could, if too large a difference in capacity/design from the house batts, could effect the overall balance and charging of your house system…

You would basically be shifting the winch to the house system, which based on typical winch usage isn’t necessarily a bad idea.

keeping the tie to the service batteries would only charge the 12v battery, and again a solid connection would mix that battery size with the house battery size and different sizes = different charging levels.

One idea would be to keep that 3rd battery hardwired to the winch, then add two small charge controllers tapping your raw panel output, one charging that 3rd battery and another connected to the 12V service battery. You could connect the 3rd to the house bank with a large disconnect to augment the house batteries, or house augment winch, if needed, like a reserve tank. The 3 systems would normally stay separated and charge independently from the house solar panels, so no balance/miss-match issues.

The charge controllers don’t need to be anything elaborate, even a simple buck converter(about$5) which will take 0-30V and deliver an adjustable output voltage, could convert the panel output to a fixed float voltage like 13.2V and apply this to the 3rd batt and the 0-12v service batteries whenever the panel output voltage is greater than the voltage you set on the power supply/chargers…
 

GeneralDisorder

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The "12v gremlins" is an appropriate name. From what I've seen on my 2008, the grounds points are one of the biggest issues. The factory coated everything in THICK CARC paint and then used star washers to pierce the paint coating and make a ground. This is valid but there was no use of dielectric grease or even paint to protect the connection. In my truck the mud wasps had a field day with many connections. I recommend finding EVERY ground and regardless of what it looks like you take it completely apart, clean (or better - replace!) the star washers and fasteners. Don't forget that the STAR WASHER is the sole connection point through the paint - which is THICK and really tough. If you have ever been on the unenviable detail of sanding and painting rust spots in the motorpool you will understand.
 

chucky

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You might be able to do that, add the 3rd 6tl to the house system. What kinda house batteries are you running? Back to the mismatch battery thing, it could, if too large a difference in capacity/design from the house batts, could effect the overall balance and charging of your house system…

You would basically be shifting the winch to the house system, which based on typical winch usage isn’t necessarily a bad idea.

keeping the tie to the service batteries would only charge the 12v battery, and again a solid connection would mix that battery size with the house battery size and different sizes = different charging levels.

One idea would be to keep that 3rd battery hardwired to the winch, then add two small charge controllers tapping your raw panel output, one charging that 3rd battery and another connected to the 12V service battery. You could connect the 3rd to the house bank with a large disconnect to augment the house batteries, or house augment winch, if needed, like a reserve tank. The 3 systems would normally stay separated and charge independently from the house solar panels, so no balance/miss-match issues.

The charge controllers don’t need to be anything elaborate, even a simple buck converter(about$5) which will take 0-30V and deliver an adjustable output voltage, could convert the panel output to a fixed float voltage like 13.2V and apply this to the 3rd batt and the 0-12v service batteries whenever the panel output voltage is greater than the voltage you set on the power supply/chargers…
What if i keep the 3rd 6tl tied to winch and put a on/off switch between the truck 12v and house 12v so it would only get charged when i wanted it too by simply turning one of the switches for a while and probably letting the solar charge it and it being on the end of the charging line from solar thru both house batts then finally ending in the 3rd 6tl but have the option on occasion to charge from the truck and most likely while useing winch but pulling from all 12v if its alot of hard winching what do you think?IMG_1780.JPG
 

chucky

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You might be able to do that, add the 3rd 6tl to the house system. What kinda house batteries are you running? Back to the mismatch battery thing, it could, if too large a difference in capacity/design from the house batts, could effect the overall balance and charging of your house system…

You would basically be shifting the winch to the house system, which based on typical winch usage isn’t necessarily a bad idea.

keeping the tie to the service batteries would only charge the 12v battery, and again a solid connection would mix that battery size with the house battery size and different sizes = different charging levels.

One idea would be to keep that 3rd battery hardwired to the winch, then add two small charge controllers tapping your raw panel output, one charging that 3rd battery and another connected to the 12V service battery. You could connect the 3rd to the house bank with a large disconnect to augment the house batteries, or house augment winch, if needed, like a reserve tank. The 3 systems would normally stay separated and charge independently from the house solar panels, so no balance/miss-match issues.

The charge controllers don’t need to be anything elaborate, even a simple buck converter(about$5) which will take 0-30V and deliver an adjustable output voltage, could convert the panel output to a fixed float voltage like 13.2V and apply this to the 3rd batt and the 0-12v service batteries whenever the panel output voltage is greater than the voltage you set on the power supply/chargers…
if possible show me the converter your talking about and i will get them and see if this will be a better way to run a 3 battery system ! THANKS .
 

Ronmar

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Well there are lots of dc-dc supplies to choose from, for a standalone battery this size that will see service i would want at least 10A. Here are some amazon search results, you want an adjustable output voltage so you can set an appropriate float voltsge.


A little fancier(and perhaps more expensive) would be a 10A solar charge controller. These range all over the place in price, with some not too much more expensive than a basic dc-dc supply. They have the advantage of delivering automated charge control…

 

chucky

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Well here comes numnutts with more questions!!! I looked at the stuff you sent from amazon and am i supposed to put one of these circut board looking thing s between the house batteries and the 3rd 6tl and on the hot cable inline or where? and can i use my idea of putting the on/off disconect between pos post on 3rd 6tl and the neg of the 24v battery so i could charge the 3rd battery with the truck altenator ever once in a while ? And these dc/dc boards dont look like theres any way to run 2/0 battery cable thru them and onto the 3rd battery ?
 

Ronmar

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The supply power for the converter/charger comes from your raw panel output(between panel and existing house solar controller). The output of the converter charger connects to the 3rd battery. Only 10A, no 2/0 cable anywhere in this part.

yes you could tie the 3rd battery to the 12v side in the service bank, but with the service 12v side already having it’s challenges, I would not recommend it.

If the 3rd is tied to the solar on the roof with it’s own charger, and only used for the winch, there should never be any need to charge it…
 

chucky

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The supply power for the converter/charger comes from your raw panel output(between panel and existing house solar controller). The output of the converter charger connects to the 3rd battery. Only 10A, no 2/0 cable anywhere in this part.

yes you could tie the 3rd battery to the 12v side in the service bank, but with the service 12v side already having it’s challenges, I would not recommend it.

If the 3rd is tied to the solar on the roof with it’s own charger, and only used for the winch, there should never be any need to charge it…
Now im already using a controller from solar to house batteries so go in behind my other controller and ad this dc/dc thing or just run a piece of #10 from my controller to the 3rd 6tl instead of the 2/0 i have down there now ! or your saying tap in the line coming from panels before it gets to solar controller then onto the 3rd 6tl
 
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