I have a 04 ford expedition I bought a new battery maybe a year ago and just...

[MizzLady]

...change alt and battery light stil? On it blinks on and off. If I cut the air on while the truck on the battery line go always down what is the cause of my battery draining and why the battery light still on

 

[GeelMan]

I am thinking that there is a plug that plugs in to the alternator and it does get soft and burns out on the inside which causes it to not let the proper amount of amperage go to the battery to keep it charged. I have replaced a ton of them and fixed the problem. You can also take your vehicle to auto zone and they will run the codes on it and check the battery and alt. for free of charge.,,,,,,,,,,,,,,,,,,,,,,,,,,

 

[AdamK1]

your alternator could be the culprite in this case, not putting out enough amps to power everything

 

[jim123]

Don't drive truck for a day. Un plug alternator and see if power drain is gone.

 

[marine_semperfi_jarhead]

Is the belt tight, is the belt tensioner worn out. Go to the local autoparts store and have them check your battery and alternator they will do it for free.