Join Date: Mar 2002
Location: Austin, TX, USA
The alternator has a "diode tree" made of 9 diodes to rectify the AC field created by the alternator's windings. If one of the diodes gets leaky it will drain the battery. Depending on your alternator, you may be able to locate and test the diode tree. It is a little black chip about 3/4" X 1/4" with four legs oriented in a modified Y configuration. An auto parts store should be able to set your alternator up on a test bench and tell you for sure if the diodes are good if you don't want to tear into it yourself.
68 Coupe, 350 w/ Edelbrock Performer RPM heads, cam, intake, 700R4, Dave's small body HEI