Alternator on the blink

[Sparky191]

My alternator is on the blink. Its not charging the battery at low revs (under 4k). I'm having it fixed tomorrow. But I was curious why its only low revs that it doesn't work.

 

[siztenboots]

My alternator is on the blink. Its not charging the battery at low revs (under 4k). I'm having it fixed tomorrow. But I was curious why its only low revs that it doesn't work.

Aux drive belt tensioners perhaps. The low rpm thing, who knows