In my 2014 F250/6.2, if the truck sits unstarted for 10 - 14 days it will usually kill the battery. I mean dead enough to not even power the dome lights.
Do the various modules in these trucks draw that much that it would cause this? I'm getting ready to install a couple of 5 Star tunes in the truck. But if I need to take it to a dealer for some warranty coverage for this problem I'll hold off. There's never been a tune in it to this point and I don't want a warranty claim denied for that reason.

 

Do you have an aftermarket subwoofer or something else that draws power constantly? My truck gets started every day so I've never noticed that. I would check all battery connections if that doesn't work take it in to the dealer if its under warranty. My 2000 mustang has sat for a month and it starts right up in the middle of winter.

 

My 2007 Mustang also sits, sometimes 2-3 weeks in the summer between drives. Never an issue there either. This truck sits because I bought a 2003 Cadillac to beat around in for winter. This is saving mile and salt exposure on a truck that I've got some years of payments left on. I've only been driving it if I need to haul something in the back or if it snows much because the Cadillac is RWD and sucks in snow.
I've got a Jensen head unit in place of the factory unit. But I bought the correct harnesses and it was all plug & play, no cutting of any factory wires. To the best of my knowledge it completely shuts down when the truck is turned off. There are no after market amps, subs or anything of that nature. All factory sound equipment other than the head unit.

 

you got something drawing or bad ground on something. My Challenger sits for 4-5 months during the winter and fires right away. I would think in most circumstances newer battery, you should be able to go at least a month.

 

You've got a bit of a "Catch-22." You've probably got some sort of extra power drain somewhere, but as a result of deeply discharging the battery to the point where it won't turn on the dome lights (multiple times?), you've also "damaged" the internal chemistry of the battery so it will no longer hold as much charge as it used to. That, and it's cold where you live in Upstate NY, so the battery's got even less reserve to work with, so the battery "dies" a bit quicker each time.

When I first shut down my truck, it draws about 300 to 400 milliamps for a couple of minutes, and then as the electrical/computer systems go into hibernation, the power drain goes down to < 50 milliamps. I've left my truck at an airport lot for 3 weeks last winter and it had no problems starting. (granted battery was only 6 months old at that time).

You're most likely gonna need a new battery, but before you buy one, look for any other aftermarket item that's not completely shutting off, i.e. two-way radio gear, anything left plugged into one of the 12V dashboard accessory plugs (they are still alive without the key), etc., etc..

If it's not aftermarket stuff causing the current drain, you may be able to find the problem without going to the Dealer. If you're comfortable playing with Electrical stuff on your truck and you've got an Ammeter, you can measure current drain by disconnecting battery and putting the meter in series with (+) battery terminal and the cable. (Don't turn anything on or try to start the truck or you may fry the meter.) After allowing a couple of minutes for things to "hibernate" check the current draw. If it's higher than ~50 milliamps, then start pulling fuses one by one. It's kind of a tedious task, but if the current drops appreciably when you pull a particular fuse, you may have found the culprit system that's creating the drain.

If there's no extra current draw - then have the charging system checked when you go to buy that new replacement battery.

 

Maybe try checking the voltage on the battery. My battery will read 12.6 volts in the morning. If you check yours it should be a least 12.3. How's the serpentine belt? Check ground wires too.

 

It's charging right now. I've got to use the truck today for a few things. After driving and getting the charge back to where it should be, I'll test the battery with my digital tester. Then I'll try the positive terminal/cable test that RightWing suggests. Then I'm done with it. The truck is just under 2 years old with a little over 17,000 miles on it. Ford can fix it.
As it stands, there's only the aftermarket stereo head unit, which powers off when the truck is turned off. There are no other accessories plugged into the 12V ports or the OBD II port.

 

Either way it's safe to guess that the battery is needing replacement get something with a little extra kick.
I just went through this with my '12' granted the battery is a little older but they normally last longer except for I get lazy and leave the Sirius plugged in at night and the 3 accessory plugged in, when it hit the freezing temps it start to fail with cranking the truck over.
Replaced with this battery with a little extra kick..Super Start Extreme 65EXT - Battery | O'Reilly Auto Parts

 

I don't like taking my truck to the dealer cause I need it everyday for work. But I would try a couple more things then take it to them. Good luck!

 

Take it in to a auto shop (NAPA or someplace like that) and have them LOAD test it that way they can see if the battery is not really holding a charge.

 

Did anyone mention the alarm system yet? Do you have an upgraded or aftermarket one? I just read that they can draw anything from 10-25ma when the trucks off, and armed. That could kill a battery in 10-14 days.. So Your prob about normal.

 

Agreed get the battery tested. My 11 was doing that but a lot worse. Dealer replaced the battery, a year later it was testing low so they replaced it again with an 850 CCA battery.
Haven't had a problem since.

 

You need a new battery then get a battery tender. Problem solved. Ford cars and trucks have a tendency to kill batteries. My GT500 will kill a battery in 2 weeks. so I got a battery tender and no more worries. You need a new battery so don't bother testing it. When you drain it so the dome lights dont come on than the battery is junk.

 

Thing is hes under warranty, why mess with it. Beyond checking connections at the battery and making sure hes not getting an obvious draw, I wouldn't go monkeying with it.


I live 20mins from Canada in Upstate and never had a battery issues like this. My guess is the battery is just bad and should be covered under warranty. My other guess if its not that, is the after market head unit is drawing something, which ford will find and fix, but there will be cost.


To be honest with CDs not in use anymore and factory head units accepting ipods, and blue tooth connections, not something I would even bother switching anymore.

 

Fortunately for me, my business is shut down this time of year and I have another vehicle to drive. So if it has to go there I can live with it for a short time.