bigbrainonbrad New Reader
9/17/09 4:38 a.m.

Little sisters car has died a few times lately, aaa put in a new really expensive ($100+) battery, I had the alternator tested at az and it passed, and the belt is both visibly new and tight. The light only comes on above 3K rpm and as soon as the revs go down the charging light goes off. That would indicate to me that the belt is slipping, but I assure you that it is not. I don't know the details of az's alternator test but is it possible for an alternator to charge only at certain rpms?

Luke Dork
9/17/09 6:06 a.m.

I had similar on-going charging issues with my Alfetta. Are you quite certain the belt is tight enough? (It wasn't, in my case, although it didn't make any sort of slipping/squealing noise.)

Otherwise, the voltage regulator?

foxtrapper SuperDork
9/17/09 7:00 a.m.

Many a bad alternator passes the bench test.

iceracer HalfDork
9/17/09 9:22 a.m.

At higher rpm the brushes are loosing contact with the slip rings. New brushes will probably cure your problem.

Carson Dork
9/17/09 10:00 a.m.

NAPA typically has brushes in stock for your app. I think they were less than $3 when I got them less than a year ago.

poopshovel SuperDork
9/17/09 12:19 p.m.
foxtrapper wrote: Many a bad alternator passes the bench test.

BIG_PLUS_ONE. And visa-versa. Have it checked somewhere else.

Strizzo SuperDork
9/17/09 2:23 p.m.

when the oem alternator started to go out on my f150, it would do that, until the battery light finally stayed on.

then the replacement had the brushes stick. pulled it off and put it on the bench tester, nothing. so i took a 1" open end wrench and gave it a whack, and all was good again.

i still swapped it out under warranty though

digdug18 New Reader
9/18/09 11:48 p.m.

It could be that the voltage regulator on the alt is heating up and deciding not to give any power to the battery... I know its a common problem in stereo competitions.

Have you tried asking this question on any of the honda specific threads? You might be able to find someone in your area to help you trouble shoot the problem. being the most popular. Where are you located? What year is the car? How many miles on it? If your close to PA. I can help...

Does it just happen when driving? Or will it stop charging while in the driveway just reving the motor?

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