On Sat, 24 Mar 2012 12:12:39 -0400, Gary wrote:

Hi everyone!

Any reason why AC can't be used to charge a car battery? Reason I'm
asking is that I have an old Fedtro Powerhouse charger
which is outputting AC.

More likely, the charger puts out rectified but unfiltered DC.

Put a 100mf 30 volt capacitor on the output of the charger (watch
polarity) then measure the DC voltage.

If there is no DC voltage across the capacitor, then the rectifier(s)
in the charger are toast.