Charging Batteries

[Webrep]

I have a FMTV and I think a FF left the lights on, can I charge the batteries connected or disconnect and charge each one? I only have two 12 volt chargers that do 2, 10 or 50 amp

Thanks....always something

 

[NDT]

The lights are 12 volt, so only the 12 volt battery pair will be discharged. You do not need to disconnect the batteries, just connect the charger to one of the 12 volt batteries, and the second that is parallel connected to it will be charged at the same time. Refer to the battery connection diagram to identify which battery is which.

 

[Webrep]

well maybe i have a worse situation that i thought. i turn on the power switch and get nothing anywhere.

 

[NDT]

If the batteries are stone dead, that would be expected.

 

[Webrep]

An update, I have had the front left battery (if standing facing battery box) on charge for 1 hour and if I turn on the power switch i get the low air alarm and it will try to start but not enough juice. My battery box does not have a diagram inside, anyone got a picture to share for me? I will try to charge both front batteries for a while then any suggestions on the 24 volt side charging? I have another 12 volt charger would it be usefull to use both chargers if so how?

 

[Tow4]

If you are not sure or all batteries are low, I would disconnect all of them and charge them individually.

 

[NDT]

Keep charging the battery you have been charging. It will need longer than 1 hr to come back from death. The second pair in series with the first (in back) should not be discharged and will not need charging.

 

[MtnSnow]

You can also charge the 24v banks batteries by connecting a 12v charger Pos to Pos and Neg to Neg on the SAME battery (according to the batteries posts NOT according to the colors on the cables!) just like you would a regular car battery.

 

[Webrep]

Really appreciate all the help guys I will give it a few hours and then switch to charge the other front battery on right. Anyone got the diagram that goes inside the battery box?

 

[jerry v]

if you want to spend the money napa has a 24 v charger i love it but its about 600 dollars

 

[Webrep]

Since I personally don't have a 24 volt truck and our donation/membership based poor fire dept doesn't have the money. So cant do that but we do now have 3 - 24 volt trucks and the conservation dept offered up a 5/4 on Monday after we get the FMTV in service. Need to find a 24 volt jump starting cable but those are expensive. Did pick up a military kit for changing hubs and brakes for free also

 

[NDT]

Batteries are covered in TM 9-2320-365-20-3 Chapter 7 para 48, which can be downloaded for free from the "technical manuals" tab, "present conflict vehicles" subcategory. If you have left the batteries connected, charging the left battery will also charge the right battery, as they are connected in parallel.

 

[Webrep]

Great I was just looking at the TM and I will leave it charging overnight to ensure full charge. Thank you again

 

[Webrep]

Great I was just looking at the TM and I will leave it charging overnight to ensure full charge. Thank you again

Update the charging suggestion worked and it started the next morning with zero issues....Thanks

 

[Jericho]

buy the slave cable ends on line (erik) 47.$ for two ends, build up the cables with double ought cable , I use 40 feet on each leg. 00 welding cable. don't crimp the lugs on , Silver sauter them

 

[Konichiwa512]

Each of the 4 LMTV batteries on its own is 12V. The fail-safe way to charge these with a car charger is by disconnecting them from each other and charging one at a time. If the batteries stay connected the total voltage may be 24V not 12V, regardless of where you connect the charging terminals, and the 12V charger will not work. If you reconnect a charged battery to a discharged one, they will share the charge and both end up half full. Take a photo of the batteries with the connecting cables, remove all the cables, then charge each battery one at a time. When they are all done, re-install all the connecting cables. You can take each battery to an auto parts store too and they will test it for free and tell you whether the battery has gone bad. But just give them four batteries to test separately. If you tell the auto parts store guy you have two banks of 24V in parallel you will blow his mind.

 

[NDT]

Does the LMTV have 4 6-volt batteries in series, or two sets of 12V in parallel?

As delivered, FMTVs have the two front 12 volt batteries connected in parallel, and the two back 12 volt batteries in parallel, and the front pair are connected in series with the back pair.

 

[scottmandu]

if your handy there is a simple battery charger circuit that can be made from a run capacitor and diode, which will charge and de-sulfate the batteries on an LMTV. It's a high volatge low amperage charger so it takes a few days to charge dead batteries.

 

[tburk49760]

Tell us more about this magic...

 

[ev2bfree]

I just picked up an M916 from Texarkana TX. The voltage regulator is bad so it would not charge the batteries while driving. We used 2 sets of jumper cables every night to recharge the batteries from the dual battery chase truck. The chase truck is 12 volt only, so the 24/12 volt battery pack on the M916 had to be slightly rewired by moving one wire. This works in a pinch.