With the engine off what do you have for a battery
reading.. then fire up the engine and take a idle
reading.. then bring up the revs and take another..
tell us what you have... what is the output of the alt..
you can have a bad diode in the diode bridge and will
still show output but it'll be low... to see if you
have a draw when the switch is off.. pull the hot lead
off the battery and put your test light between the
hot post and the battery cable.. that will tell you
if you have a draw (the light will light up)