Have a volt meter? Check attery base voltage not running and running voltage off idle. Should be about 14.6V running -- up from base of about 12v. If not, something is wrong. If you have a Ford regulator, I have the diagnostic Shop Tips from Ford and can scan/e-mail the appropriate pages to you.
As Naga mentioned.....turn the key on and observe what the voltmeter reads. Then turn on the car. The voltage should go up. If it does, you are charging. If not, you are not.
A few things to do to make the meter more accurate include running a separate ground wire from the meter back to the chassis or even all the way to the battery neg terminal. If you have a small ground wire and all the gauges run through it, you get a "common impedance" voltage drop. There is impedance (resistance) in any wire and the smaller the wire, the higher the impedance. Current times this impedance is voltage. That voltage is subtracted from the actual system voltage and that's what you see on the gauge. On the + side, be sure to run a single wire right to the ignition switch. Again, you don't want to share the circuit with anything else.
If you want to verify the accuracy of the meter, you can use a multi-meter and simply measure across the meter terminals. If the two match, they are both measuring correctly. You can then put the multi-meter on the battery to see what the difference in the wiring is.
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