Trouble starting

Circletrack13

If this Tahoe sits for 8-10 hours it will only click at the starter as if the starter solenoid will not engage when a charger system is applied it will start immediately we checked the battery and the alternator with a snap-on battery check instrument

battery indicates 650 CCA,
when you go through alternator check output is never below 12.9 amps lights etc on
at idle shows 14.4amps

Any thoughts