Discharging Problem

Ok looks like I had a bad meter.

Readings
Engine off Key on
Batt 13 IGN 12.6

Running Fast Idle
Batt 14.2

Loaded
Batt 15.5 ALT 14.2 IGN 15.7 AMMETER at 3/4 Charge side.

Running loaded or unloaded at idle
Batt 12.4 ALT 12.4 IGN 10

IGNITION seems to be all over the place each time I take a reading.

You spoke about putting Battery positive jumper to output of ALT, what exactly is this doing?

Thanks again for all the help.