Hi just replaced the alternator a month ago. And I notice low voltage on idle speed like 10.9 volts. I removed the alternator and chek it but in the machine the alternator is good, with load (on the machine) it gave 12.5 volts. What can it be? a faulty wire? I also checked the battery and it is fine. Please help!!!!!!!!!!!!!!!!!!!!!!

 

I would say check the grounds.
And water level in the battery unless you are using a dry cell.
Belts are good and tight?