73shark

The two alternators may not have the same capacity, ie, one may be a 90 amp and the other a 120 amp which would explain the different charge rate. Also when checking a charged battery, you need to wait about a half hour to allow the surface charge to bleed off or turn on the headlites for 30 sec and then check.

Tahoe7081

Sorry for the confusion. The old battery would show a battery light and very slow to charge from alt on the guage. A few blocks before charged. The new battery has no battery light and take maybe 5 seconds to show charged. I know 5 seconds isn't much. But, the tahoe does it quick! Wondering why?

digitaldeath

I just replaced the altenator in my 04 suburban and it takes a few seconds to hit 14.2 volts on the dash gauge from my understanding its normal
Prolly was just a faulty batt

Tahoe7081

Yesterday it no longer charged. Had local shop put a new alt in. Seems fine now. $150 for lifetime alt and $45 install fee. Thanks guys