Instrument panel keeps displaying the battery.

Use an inexpensive digital voltmeter to measure the battery voltage while the engine is running. This must be done while the problem is occurring. It must be between 13.75 and 14.75 volts. If it is low, suspect worn brushes in the generator. If that's what it appears to be, I'll look up what they used on 2004 models. On older ones from the 90s the brushes were attached to the voltage regulator and were real easy and inexpensive to replace. Ford had a fairly decent design in the 90s so they had to change it for newer models.