So my 1991 Camry 4 cyl got a new engine 2 years ago this month. I went ahead and kept the alternator I had rebuilt during the previous spring. Now when I'm out driving around, the blower and headlights dim at slow/dim at idle. Since I have only idiot lights, I don't know how much power I've got.

I assumed it was an alternator problem, so I opened the head to check the belt. (it moves about 1/2 an inch at most) There was that chalky, white powder built up around the battery post. I cleaned the battery posts, tightened the cables down and even cleaned the alternator connectors.

Problem solved for awhile.

This morning, after 15 or 20 minutes of driving, I started getting the low power-when-idling problem again. So, doesn't that rule out the alternator? Could this be a battery problem? And why does that chalky white powder build up?

By the way, none of the idiot lights have come on, like the first time my alternator went out.