OMG I have a 2008 F150 and have had dead battery every morning for a month. Have been to the auto parts store checked the battery and the alternator. Both check out okay. Put two new batteries in, started fine for about a week each. Then back to nothing. Put new alternator in and got a full 10 days then back to no start. It starts first try on jump box and then starts fine all day. Manual says it has in line fuse but we have not located such. Help please!

 

Well it sounds to me like you have a parasitic drain. You can use an ampmeter between the positive post of the battery and the positive battery cable. This will tell you how much juice is being drained. If it's more than a few miliamps, you have a problem somewhere. Sometimes you can start pulling fuses while watching the drain and when it slows way down you've at least narrowed the source by seeing what that fuse controls.

 

What has an in-line fuse ??

 

the wiring to the alternator

 

Maybe he meant "fusable link?

The lead from the battery to the starter, alternator, and fuse box all use a "fusable link, meaning that if any one of these leads shorts to ground, it "melts", and has to be replaced.

However, since it starts from a jump, it would not be a fusible link.

Has any "accessory" been installed right before this happened?

You can place a meter between the battery and positive lead to check for a "load" when the truck is parked and off. This would show that there is indeed a "draw" on the battery, and if that 'draw" is significant enough to drain the battery after a day.

 

I think you hit the nail on the head. Not fun to find but I think this is his problem also.

 

The truck was in fords service dept for power window repair. Thats about it. Nothing else I can think of. I will absolutely try your ideas. We just did not know where to even begin. It sounds like you guys can help get this figured out!

 

Could it be that motor for the window? It was installed about a month before these issues, then about one month later it started making a little noise. And the CD Player is keeping a CD in it this too just started.

 

Bella, take a look at this thread. Its similar issues and after the user replaced the power window, the problem vanished. I believe wires were fraying and shorting out causing the truck to have a small short and kill the battery.

https://www.f150forum.com/f4/random-no-start-290197/

 

Started with the power window relay the ohm meter was running 13 voilts with it in and took the relay out and it is now down to 10. So I guess its not the power door relay. Any other ideas where to try next? Thanks guys this has been two months of heck and allot of money. Is there anything else door that would have its own fuse?