M936 Battery relocation

[bigboy44]

I move my batteries ans slave reciptical this morning so I can patch the rotted out hole in the floor. I was just going to move the batteries but I liked it so much I moved the slave also and after talking to Csm Davis I think I am going to take his advise and add another battery and a 12 volt alternator. I will do the addition at a later date, I took all the measurements and it will go with 1 1/2" of space between the three batteries.

If any one else does this put the slave reciptical in first it is easier! I do not like the wires going as close to the exaust like they are now, just went to NAPA to see if they had something I could put over the wires for protection against the heat of the exhaust they did not(any help will be appericated on the heat issue). I may have to make the wires longer and reroute them. My ground wire was too short to reach the battery as they are so I put a 3/8" bolt through the box with a wire on each side of the box, the wire will reach when I add the other battery.

I do not know if I will put the battery box back in the cab, I may move the drivers seat to the passengers side and get a air ride seat for the driver. Does anyone know if a new rubber mat can be had without the cut out for the battery box?

If you see anything wrong with this mod please let me know. Thanks for looking!

 

[Artisan]

GREAT job! I would love to move mine but
I equally love the storage space. Moving them
also lowers teh COG of the vehicle as well, a lot,
no but it does.

Now you have room to mount 3 MasterCraft
seats all on stock spring over shock pedestals!

 

[timntrucks]

so you are just runnng 2 batteries and not 4? how well it hold up and how does it start with just 2 batteries. i am going to move my batteries on my 923a2 this coming summer

 

[rangereter]

Warren,
I think the relocation is a very good idea. Do you think that a piece of 1/2" marine plywood cut to shape would do well on the floorboard? It is cheap, paintable, noise and temp absorbing, and would be a suitable mounting base for most anything.
Regards, Bob

 

[Scarecrow1]

Good job on the move, I have two commercial batteries still in side the cab each with 900 cca,s. Two works just fine instead of four . I am looking into the possibility of an independent 12 volt battery also so please keep me posted on your progress with yours.........

 

[wreckerman893]

so you are just runnng 2 batteries and not 4? how well it hold up and how does it start with just 2 batteries. i am going to move my batteries on my 923a2 this coming summer

Tim.......in the southern climates two high CCA batteries will do just fine for deuces and 5 tons. The military uses four because the trucks spend a lot of time just sitting in a Motor Pool and batteries do slowly discharge. They also have to be able to start in sub-zero climates and four batteries will have more stored CCA than two. Most active duty units have "Motor Stables" at least once a week where vehicles are PMCS'd and cranked.
Trucks that have the two stroke Detriot engines would probably be better off staying with four batteries since they have higher compression than Cummins, Cats or Multi-fuels.

 

[quickfarms]

Most commercial trucks today only use two or three truck batteries. If you use block heaters this will work on cold climates. The military uses 4 batteries go the redundancy and ability to start in artic conditions

 

[FireFighterHill]

Im going to be using a battery equalizer and have 2 in 12volt and 2 in 24volt. I already have a 60 amp VANNER Equalizer. Im going to be adding an extra toolbox on top of the existing one behind the cab and mounting them all in there. I also plan to have an on board charger as well as a solargizer. Later down the road I may add a separate 12volt alt or maybe a dual voltage alt.

 

[bigboy44]

Mr Tim,
It starts great even in the cooler weather we have down here, they have 95 cranking amps each. I was going to do this as temporary but I think I am going to leave it that way and put 2 seats in the cab and a small console in the middle.
Thanks

 

[bigboy44]

Warren,
I think the relocation is a very good idea. Do you think that a piece of 1/2" marine plywood cut to shape would do well on the floorboard? It is cheap, paintable, noise and temp absorbing, and would be a suitable mounting base for most anything.
Regards, Bob

Bob i have a piece of conveyer rubber that I could use to cover the hole in the, just thought a one piece would be better.
Thanks

 

[timntrucks]

2 batteries in that truck would save me alot or room

 

[BKubu]

BIGBOY44, I like your truck. It is getting rare to find any M939 series vehicles that are still left in their 4 color MERDC camo scheme. I, for one, prefer that scheme. I also think your movement of the battery location makes sense and I like the job you did. I am guessing that you know about this, but I'll mention it just in case...they make a real battery relocation kit for this series of trucks. It is a bit pricey, but it is very cool. I have not yet installed it on one of my trucks, but I plan to do so.

 

[goldneagle]

Im going to be using a battery equalizer and have 2 in 12volt and 2 in 24volt. I already have a 60 amp VANNER Equalizer. Im going to be adding an extra toolbox on top of the existing one behind the cab and mounting them all in there. I also plan to have an on board charger as well as a solargizer. Later down the road I may add a separate 12volt alt or maybe a dual voltage alt.

I have an extra tool box on top of my existing box and the weight seems to be effecting the lower box. The door lock is getting harder to close due to misalignment. I think the upper box weight is warping the lower one. I do not have anywhere near the weight of batteries in it. (1" impact gun, tire hoist)

You may want to consider either reinforcing the bottom box or switching the two boxes (put the battery box on the bottom and the existing box on top)

 

[wreckerman893]

they make a real battery relocation kit for this series of trucks. It is a bit pricey, but it is very cool. I have not yet installed it on one of my trucks, but I plan to do so.

Some of the trucks that came out of Camp Shelby had those kits (the up-armored ones more so but they were not sold).
Csmdavis may have an inside line on some of them.

 

[Vintage iron]

My customer is requesting that I install a battery relocation kit like this on his truck. I have found that they are hard to come by right now or very expensive. So my solution is just use the existing side box under the passenger's side door. It will hold 4 Series 30 commercial battery. I will reinforce the floor of the box and add an extra heavy coat of paint. The cables are the easy part. I will post some picture.

 

[FireFighterHill]

Thanks for the heads up! I guess I will see about building a frame for it to rest on and bolt to out of angle iron to support its weight. I dont even know if I need 4 batteries with what im planning to do. I was thinking of running 2 in series and 2 in parallel and letting the equalizer keep the parallel 12volt batteries charged. I'm just not sure if im asking to much from the equalizer. Or if I should leave it in a 2+2 and parallel the 2 separate 24volt pairs to double the capacity and let the equalizer power all my 12volt accessories. Im inclined to separate the batteries into a 24 and a 12 volt setup so if I was to drain the 24 volt system accident I could still use the other 2 to start the truck and get me home. Any thought?

I have an extra tool box on top of my existing box and the weight seems to be effecting the lower box. The door lock is getting harder to close due to misalignment. I think the upper box weight is warping the lower one. I do not have anywhere near the weight of batteries in it. (1" impact gun, tire hoist)

You may want to consider either reinforcing the bottom box or switching the two boxes (put the battery box on the bottom and the existing box on top)

 

[timntrucks]

im all ears an waiting on some pics.. thanks guys for all your input and the pics too

 

[Vintage iron]

I should have pictures of alternative battery mounts up in about two weeks. I need to send some parts that include this box out for sandblasting.

 

[bigboy44]

BIGBOY44, I like your truck. It is getting rare to find any M939 series vehicles that are still left in their 4 color MERDC camo scheme. I, for one, prefer that scheme. I also think your movement of the battery location makes sense and I like the job you did. I am guessing that you know about this, but I'll mention it just in case...they make a real battery relocation kit for this series of trucks. It is a bit pricey, but it is very cool. I have not yet installed it on one of my trucks, but I plan to do so.

Thanks, I seen the kits but too much for my pay scale!

 

[goldneagle]

Thanks for the heads up! I guess I will see about building a frame for it to rest on and bolt to out of angle iron to support its weight. I dont even know if I need 4 batteries with what im planning to do. I was thinking of running 2 in series and 2 in parallel and letting the equalizer keep the parallel 12volt batteries charged. I'm just not sure if im asking to much from the equalizer. Or if I should leave it in a 2+2 and parallel the 2 separate 24volt pairs to double the capacity and let the equalizer power all my 12volt accessories. Im inclined to separate the batteries into a 24 and a 12 volt setup so if I was to drain the 24 volt system accident I could still use the other 2 to start the truck and get me home. Any thought?

The equalizer does not function like an inverter. It does not power anything. You do not attach any loads to the equalizer directly. The loads go to the batteries. The equalizer just keeps the voltage level in the batteries equal. When you drain the 12 volt battery you tapped, it will take power from the other batteries to keep the voltage in the system equal in all batteries. That way when your alternator recharges the batteries they all get charged equally.

It's kind of like a water level...it keeps trying to level out the water in the containers.