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-   -   Alternator whine. (https://www.cruisersforum.com/forums/f13/alternator-whine-233882.html)

Bycrick 10-05-2020 16:01

Re: Alternator whine.
 
Measuring alternator whine. First, most inexpensive AC voltmeters donít actually indicate the correct voltage unless the AC is a good sine wave. So to measure the ripple, youíll need a meter which read True RMS. Second, based on the several articles I found, there doesnít seem to be a good agreement on how much ripple is "too much."

So Iíd probably try to find somebody that had the good AC meter. Theyíre much more common than an o-scope. If you read a few hundred millivolts of ripple, youíre probably OK. If itís several volts, then you can take the alternator apart to check the diodes.

When you install a new alternator, measure the ripple right then. It gives you a baseline for detecting future problems.

Compass790 10-05-2020 16:05

Re: Alternator whine.
 
Quote:

Originally Posted by Bycrick (Post 3136701)
Measuring alternator whine. First, most inexpensive AC voltmeters donít actually indicate the correct voltage unless the AC is a good sine wave. So to measure the ripple, youíll need a meter which read True RMS. Second, based on the several articles I found, there doesnít seem to be a good agreement on how much ripple is "too much."

So Iíd probably try to find somebody that had the good AC meter. Theyíre much more common than an o-scope. If you read a few hundred millivolts of ripple, youíre probably OK. If itís several volts, then you can take the alternator apart to check the diodes.

When you install a new alternator, measure the ripple right then. It gives you a baseline for detecting future problems.

Ok thanks for that.


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