Just happened to be in the Subaru, but this is a pretty generic question about charging system.
Yesterday went out to start the car, stone dead. Figured battery is about 6 years old, go get a new one.
Car starts fine, tach needle is bouncing up and down, (rpm is not varying by sound), am showing about 14v on gauge, flip defroster on, and down in discharge, maybe 10-11v. Revving engine doesn't change discharge.
Swap out alternator, system is happy.
Can a bad alternator drain a battery, or was this coincidence that the battery was dead, and the alternator failed? (had suspected it was going, as voltage was climbing a bit, I'm figuring the regulator was getting tired).
Thanks Mark