It could either be because your alterneator is going bad, or that your alternator belt is loose. Theres an component in the alternator that sends a signal to the dashboard for the battery status. Most often on reconditioned alternators, this component goes bad but it does not affect the overall performance of the alternator
Why would battery light come on then go off
If it is undercharging the battery yes, but if it is overcharging the battery no in most instances. If it fails completely the light will come on.
what causes the battery light to on a 2005 ford expedition to come on?
Your battery is probably dying
battery is on its way out or its not charging properly
NO! where does the power (voltage and current) come from if the battery is flat/dead?
Check your alternator belts. Might be slipping or broke.
A bad stator causes the battery not to charge. That makes the battery light come on. Some other things that can cause the battery light to come on are corroded or frayed cables or connections or a loose/bad ground cable.
If your battery is not being charged , the battery light will come on in your dash