what would keep the battery from charging after changing the battery and alt.?

fully charged battery should be 12.6 volts with engine off.with engine running battery voltage should be 13.5-14.5 volts, DC.if not,most likely bad,new alternator out of the box.battery is for starting the car,then alternator takes over,to supply correct voltage to everything.

*TEST ALL* fuses with test light!!