05 duramax batteries getting drained

[farm boy00]

So I go to start my truck lately (currently it's just a farm truck) and every other day batteries are so dead that it won't roll over. We can't figure out what has been causing it. The batteries are only a few years old. Alternator less then 8 months.
Truck has a front snow plow, salter and back up lights that ain't hooked up yet. Salter is unplugged because the plug broke on the truck end and plow hasn't been hooked up in over a month because the tranny cooler is bad. So nothing aftermarket is running. The driver door does sag but you can lift it and it shuts just fine. We can't figure out what's going on. Dome light has a timer but it didn't go off last night when I didn't shut a door hard enough but even though the door wasn't shut the dome light should have gone off. Went and reshut the door and it went off.

The truck has around 427,000mi but nothing has acted up like this before. You guys got any idea.

Now I have to go start the truck every morning and run it for a while to keep batteries charged. Not a big deal but I shouldnt have to do it

 

[Deere Dude]

I would take the batteries out and have them checked as some stores or garages can do that, or just take it down. They may be able to put a load test on it while in the truck.

For me, it sounds like you have a bad battery, or two. One may be bad and drain the better one.

If you have the batteries charged and the cables disconnected and then when you hook up a battery if you get a few sparks, that should tell you if there is a draw downstream.

 

[davesl708]

If the batteries check out look for loose ground wires. I chased a drain for months on my 04 Suburban. Are any of the gauges reading differently?
I found my drain the switches on the driver door. The switch kept making contact inside activating the computer and would drain the battery in less than 10hrs.

I hope it is the batteries but my 03 Trailblazer also had electrical problems that took a long time to track down.

 

[Diamondpilot]

I believe the GEM module or whatever it's called has been a issue. Look into that.

Chris

 

[farm boy00]

I would take the batteries out and have them checked as some stores or garages can do that, or just take it down. They may be able to put a load test on it while in the truck.

For me, it sounds like you have a bad battery, or two. One may be bad and drain the better one.

If you have the batteries charged and the cables disconnected and then when you hook up a battery if you get a few sparks, that should tell you if there is a draw downstream.

I'll see. Probably won't take them out or to a shop. These Chevrolet batteries have those ends that ain't the easiest to get into and Thier positions are under cross supports. And the truck ain't leaving the farm unless it's a emergency

 

[the old grind]

OEM battery charging isolator hooked up ok and diodes not shorted or 'open' there? Could be that only one batt is being charged, and we are told that connecting batteries in parallel without an isolator can shorten their lives considerably, esp if one is aging out of sync with the other.

I'm South of Sand Lake and this Winter (last two) had me scrambling to keep batteries topped up with the temp fluctuations. Snow equipment batteries get the worst shake during the Winters we use them the least. (light snow 2 yrs in a row)

Last week my (road) truck wouldn't start (temp in teens). Starter terminals were badly corroded and freshened-up when I replaced it. My car would only 'click' Thurs morning (~4^ F) but was ok by mid afternoon and temp up into the 20s. A dome light/timer can draw plenty o'night in the coldest weather.

Even HFT's $10 DVM has a 10A 'transit' (w/test lead socket) for measuring DC amps. (know/learn how to use it) Use such to measure current leakage with everything turned off and connected in series to each battery in turn at the + post. Don't ignore ground connections (engine/chassis/body) when analyzing starting issues. Good luck!

 

[farm boy00]

Only thing that I am thinking now that I am thinking hard about it is there is a ground cable from the hood to the truck that is cut. I'll replace it tonight,and see what happens

 

[Diamondpilot]

I would also test the alternator. Could have a live field.

Chris

 

[terryknight]

separate the batteries and test them. charge them. put a meter on them and if there is a draw you will see it. then start pulling fuses until the draw disappears. that will narrow down the circuit that you will need to inspect

 

[arkydog]

i have an 01 duramax, and a few year back i had same problem. they were some auto zome or walfart or something. batteries checked out good. on one of the diesel sites for duramaxs said just replace batteries, both at same time. did that with good batteries that you can get from a truck repair shop that handled interstate batteries and fixed the problem.. just couldn't believe it was a couple of year old batteries. fought for a couple of weeks. new GOOD batteries have lasted almost 6 years now. if you pm me i will give you the duramax sites. they have been a great help. i even replaced alternator and that wasn't it.