On Tue, 30 Dec 2003 03:39:24 GMT, Doug Van Horn
wrote:

Had a similar problem with my old Heathkit battery charger - it won't
charge unless it sees at least some voltage across it to begin with so
it knows it's connected to a battery. My solution (since I had the
circuit diagram) was to add a couple of wires from the plus and minus
sides of the internal bridge rectifier to red and black binding posts
that I added to the front panel. That gave me a little over 16 VDC
under load that didn't care whether or not a battery was hooked up.
Total cost zip, since I already had the binding posts and wire.

TT

I wanted to post my experience with this so as to help others who might
try this. When I went about trying to gather all of the necessary
pieces together for this type of rust removal, I had the hardest time
finding a power source.

You see, it seems that many modern battery charges are equipped with
some kind of polarity protection (or some such nonsense). This
prevented the chargers (2 different ones) I purchased from providing
current to my rust removal system. Presumably they wanted a battery at
the end of the cables.