Dead Battery Situation-M35a2

[wvhillbilly]

In the last month the batteries on my Deuce are completely drained after sitting for 7 days...so drained they will not even register 4 volts with a battery tester. I recharged them, used the truck, parked it, came back the following weekend....SAME THING. Recharged again, and used the truck. Now I am disconnecting the jumper cable between the two batteries and am having no issues with discharging.

Other info: Batteries are 2 months old(Group 24, 800CCA), Generator output is
27.4V.

I am considering installing a disconnect switch in the ground cable and calling the problem fixed. Any thoughts as to what the root cause of this problem is?

 

[dittle]

Anything electrical that can draw is a possibility. Could be the alternator or any of the gauges drawing if the master switch isn't working properly. Master disconnect is the easiest fix plus it gives you a little bit more of a security check if you do any events where people are in the cab of your truck.

 

[wreckerman893]

Are you sure little hands aren't flipping the battery switch on while the adults aren't around.

With the batt switch on the low air buzzer will come on if the air leaks down, draining the batteries.

 

[doghead]

Do you turn the light switch off(top lever straight up) every time?

 

[Heath_h49008]

You have a draw... Check for current flow with everything shut off. There should be nothing if you're stock. Modern cars pull a small amount for the computer, radio, clock remote start, alarm, etc...

Now, with Soldier II watching the multi meter, start disconnecting circuits one by one for lights, pumps, heaters, radios and anything else electrical until the draw stops. Repair as needed.

 

[hoop]

Start your check with the Alternator.

 

[wvhillbilly]

Confirmed master switch was always in the off position

 

[swbradley1]

DH is correct about the switch. I have left my gauge lights on a couple of times and drained the batteries down. You can't tell if they are during the day and they aren't much better at night.

 

[glcaines]

It looks like you have a heater from your avatar. Make sure the heater blowre switch is off as the heater is not powered through the master. Otherwise, do as others have suggested. You have a current draw and you need to isolate it circuit by circuit.

 

[wvhillbilly]

Heater switch was off in both cases..

 

[Heath_h49008]

http://www.steelsoldiers.com/deuce/3843-peter-bogs-cad-deuce-schematic-9.html#post707049

There is no fuse panel per se on the M35A2... so you are going to need to disconnect each switch by pulling the plug. Just because it is in the "off" position, it doesn't mean the circuit isn't flowing current. You are looking for a bad switch/relay of some kind that is staying stuck "on" or shorted to ground. Something says "off" but really isn't.

 

[AceHigh]

I put Caterpillar battery disconnects on my trucks, real easy to just drill a hole in the passenger seat area, hook the ground cable to one side of the switch and install a short cable from the switch to the battery. On the plus side, each of my trucks use the same key.

Also one time I had the same problem and found the problem was a slight coating of something on the top of the battery conducting current. Cleaned the battery top and was good to go.

 

[Darwin T]

i have one duece that the batteries had the same issue and now the batteries are dead and gone. i am going to install new batteries in my M109a3 and move those batteries to the one without batteries. however i have benn researching the 24 volt priority start system. it shuts down the battery drain when the batteries still have enough power to start, even if you forget something on or just have a slow drain. start it up and let it charge back up. i am also going to pull the radio gear out and see if that helps. if that does not work then the radio gear goes into the M109a3 box (installed not just like the other 20 boxes of stuff thats not installed yet).

PriorityStart - 24-Volt ProMax Information

 

[phil2968]

Leaking diodes in your alternator will drain your batteries. It just takes one bad diode in the bridge. A disconnect in the negative cable would stop the discharge but you would still have a questionable diode bridge. You can check for current flow at the alternator with a 10 amp or bigger amp meter. Put the meter in line between the alt and it's output cable. You should not have any current flow with the truck shut down.

 

[marchplumber]

similar problem. Found draw on alternator. Put in ground disconnect. Trucks been fine ever since. I realize it isn't a "repair", but it is a "fix". I will get an alternator this spring and install.
God bless,
Tony