spider_1954

Again! for some unknown reason my truck can sit for a week with no problems then for some reason both batteries will go dead like I left the key on or something (no key was not left on) I put a battery charger on both batteries and on one of the chargers the needle was going back and forth like something was come on then going off!
The truck has already been to the shop for this but no problem was found.

RRAMctd

could be a bad battery. They can get loose inside and short out. your truck is kinda new but its a better idea then you have a short in your wireing somewhere. I have a old dakota that does that, or rather did that, now it seems to be fine again. Glad I don't rely on that thing for much.

RAMRODD

On a 06 if you leave the key in the ignation your Sirus Satalite stays powered and this will drain your battery over time. Your 07 may be the same way. This has happened to me a few times I finally got in the habit of pulling the key and throwing it on the dash.

Do you have your battery's unhooked from each other while Charging??
I would only use one charger for both batterys.

northernwheeler

I just went through the same thing. When I first bought my truck, all was good, could leave it for a few days with the key in the ignition and it would still start. After about a 7-8 months I noticed that when i would leave it for a few days it would have low batterys.

Finally it got to the point that overnight it would not start the next day. Through all of this the batterys tested OK. Even brought it to Dodge and they said all was OK. I finally got sick of boosting it all the time so I went and bought two new batterys, and it is fine now. Can leave it for days and it still starts. Funny thing is, if you load test the old batterys, it still says there OK, but one of them has a internal problem.

Purplezr2

Had the same issue with my 2nd Gen truck, Bad batteries.

johnh

my friend has an '06 that did the same thing, after a lot of testing the dealer replaced the alternator, no more problems.... the truck had less than 10000 miles

TreeFarm

Having two chargers connected at the same time without disconnecting the batteries from each other would account for the wild swinging of the one charger, if it was of the automatic type.

Some automatic chargers regulate by turning themselves on and off. The higher the charge in the battery, the longer the off time. If it was seeing the other charger, it would think the battery was charged, when it really wasn't, and you would get the wild swings.

spider_1954

Up date::
Had the truck at the dealer and they did a current test with the key in the ignition and then without and that is the problem! With key in ignition they are modules that are turned on. With the truck sitting for a week or more with key in ignition the batteries are hit with a constant current draw.
Never would have guess that this was the problem but some of you knew!!
So I guess from now on the key stays out of the truck!!

Thanks

TreeFarm

Must be more than a minimal draw to flatten two good sized batteries in only a week. That's valuable information. Thanks for the update.

JT's 6.7

I have had my 07 6.7 in the shop 3 times with no luck. Great info to give a try.

booman70

My truck is garaged but I always pull the key half way out.