Alternator acting strange....

2008
4.7
At startup.....volt meter on dash reads below center
Voltage at battery (running) 12.5V
after 45 seconds (checked this several times and is consistent)
It sounds like a clutch kicks in and volt meter on dash goes to center
and voltage at battery now at 13.8
Now I know there is no clutch on the alternator right?
Sounds just like a AC compressor clutch kicking in

 

What accessories do you have running while you are performing this test? Simple way to find out would be to just have the charging system load tested. Oh, and welcome from CO!

 

Thanks for the welcome!
Nothing on.....Just start and wait 45 seconds and you hear it kick in

 

Exactly. Always test alternator under load conditions and monitor not the volts out but the current output.

 

I'll just replace it

 

The air injection pump runs on start up for a bit, and has a noticeable electrical draw. Might be worth checking, can usually hear it running.