New alt. Battery still won't charge.

[DanRoberts63]

Hello,
Anyone know why my battery still won't charge even after I just installed a new alt?

 

[RangerX]

Maybe the battery is bad?

 

[GTMountain]

Stick your battery on a charger. Once it goes green, remove it, let it sit for 2 hours, then check voltage.

12V Battery voltage guide: 12.7V = 100%, 12.5V = 90% (these are optimal), 12.4V = 80%, 12.3V = 70%, 12.2V = 60% (these numbers are ok but you're pushing it), 12.1V is 50%, 12V is 40%, 11.75 V is 30% (this is bad and your battery is over-stressed) 11.6V = 20%, 11.3V = 10%, 10.5-11V is dead (battery is in serious trouble or has failed).

You could have a bad alternator connector or you could have a bad ground cable somewhere. Or, if it all works fine but then dies overnight, you have something drawing voltage when it shouldn't be (find it).

 

[XLTrunner]

What led you to the conclusion that the alternator needed replacing?

As mentioned, I'd be focusing on the condition of the battery. Don't rely on some auto parts store having tested it and giving it the ok as results are often unreliable.