Battery drains only when car is running... Help

lrazor said
When I read the OP on this, I too guessed that the regulator might be at fault, but after reading 67Dart's reply, I realized that following the procedure that he outlined made a lot more sense. Doing so would have verified the condition of all the components and given the OP real insight into the operation of the charging system. Anyone can replace parts, it takes a mechanic to diagnose a problem. He gambled his $30 and lucked out. If he had guessed wrong. he'd be out $30 and no closer to a repair.

BTW, just because his immediate problem is solved doesn't mean the alternator's good, it could still have a couple of bad diodes and marginal output.
JMHO

Thank you. What is going on here is known as "throwing parts at a problem."

While some of my posts may appear complicated, they are pretty simple, and you can always post back questions

THE FACT IS that it takes only minutes to make a couple of "quick checks" and reduce your guessing to a more sure thing.

I"ve know a LOT of guys who started with "a new battery," then "an alternator,", then the regulator, and GUESS WHAT? IT still didn't work right because some wire connection was broken, that could have been found and repaired in a few minutes.