today i drove for 3 hours stopped and got gas and when i started again my battery light came on and hasnt gone off since. everything seems to running fine. my battery gauge is normal and i'm not getting any codes. what is wrong?

 

Had the same problem in my Expo just today. It is the alternator if it starts up OK after sitting over night and it will run for a while, but not long. Replace the alternator and you be up to par again. $250 at Ford and $150 at NAPA
The Voltage reg. is out and your electrical system is dying a slow death.

 

Before you fork out the cash for an alt, have it tested. I had the same problem a couple of years ago, it was a loose (actually broken) wire.

 

Could be a bad pulley on the alt. or a loose belt causing your alt. to not function properly had this problem on my first car 20+ years ago. and it was due to a bad pulley.

 

The alternator in my 05 SCREW went bad after just one week of owning the truck...brand new. It would start up fine with no battery light and then the light would go on after driving for a few minutes. Ford replaced the alternator.

 

My batt light came on and vehicle ran fine. I tested the battery while the engine was running and only had 11 volts. I was on the way out of town pulling my Jeep on a trailer. I drove 160 miles pulling the trailer with the batt light on. Put a new Napa alternator in when I got home and everything was fine.