About 3 weeks ago, I began seeing the battery light indicator on the dash board come on and after a minute or two, turn off. I replaced the battery and it seemed to solve the problem. Last week, my 2013 F150 was dead in the driveway. After jumping it, I had the battery read at a local auto parts store who said the alternator was failing. On July 8th, I had the alternator replaced by a trusted mechanic. This morning (July 16th), while on my way home from work, the battery light came on twice but in both cases went away as quickly as it came on (first time since having the alternator replaced). When I attempted to start my truck this afternoon, the vehicle was completely dead. Again. To recap, the battery is 3 weeks old, the alternator is 8 days old, why is my truck still dying? Is my new alternator bad? My mechanic used a motorcraft alternator. Is there something else I'm not seeing?

Thank you.

 

Obviously. But none of us can see your truck to tell you what it is. You didn't post ANY pics of it, and you didn't tell us much about it. You should put ALL the truck's details & history into your signature as this page explains:

(click this text)


Phone apps don't always show signatures, so you may need to switch to a real browser in desktop mode on your phone, or just use a desktop/laptop computer. Post pics of the battery, terminals, underhood wiring, belt, & alternator connections.

 

Search around about the battery management system, AKA BMS. Apparently, it can cause problems, if I recall right, not sure why. It might be that you didn't actually need a battery or an alternator.

The fact that your battery died indicates a draw when the key is off.

 

After truck has been sitting for 4-5 hours is the alternator hot to the touch? If so, 99% bad alternator.

See attached video

 

The 2013 might have the "smart charge" system. The PCM is involved. The alternator should still have a "fail-safe" mode but who knows about the other various circuits involved.

Here's another South Main Auto video and a Remy one too.