Odd electrical issue

[jimmy-90]

Lately I've been having a strange thing happen when I start my M1028. When I start my truck the GEN 1 light goes out right away and the GEN 2 light goes out when I goose the motor a little but the volt meter still reads in the yellow after both GEN lights go out. I have to rev the motor a little more and then the volt meter will shoot up to where it is supposed to be. It has been doing this for a little more than a week now and the truck seems to run good but it didn't do this before. I thought I heard a belt slip a few days ago so I changed both ALT belts and it still does it. Does anyone know what might be making it do this???

 

[ctmustang]

Sometimes and not always I have seen this and it was an alternator getting weak
Test them and see what they read after you crank the truck and the gen light is still burning
Are the belts as tight as they need to be