On Mar 24, 9:39*am, Gary wrote:
On Sat, 24 Mar 2012 12:25:02 -0400, wrote:
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.

OK, except I can't see anything inside the charger that looks like a
rectifier: *aside from the main transformer, there is just a small
coil of wire (the buzzer?) and a 6V/12V switch.

Think: If you attempted to charge a battery with AC, the charge
deposited when the current swung positive would be discharged when the
current swung positive. All you would be doing is heating the battery,
not charging. Take out your ohmmeter and look to see if there's a
diode between any two points.

Also, look for modifications. When I was a sprout, we had a battery
charger purported to rejuvenate the carbon zinc cells of the day. The
light went out, and the charger quit charging. Not knowing any better,
to make it work, I jumpered the light, which apparently acted as the
charge current regulator. At which point the diode went "Sproing."
Somebody might have taken your charger's diode out in the belief it
would improve things.