Not sure what 2 1/2 mps means, but the battery light usually indicates
insufficient charging, not a bad battery. Carefully check the wiring between
the battery and the alternator, including connectors and grounds. Corrosion
can hide under insulation, even if things look good from the outside.
If you don't see anything obvious, you need to test that the battery is
being charged properly. Pay someone, if you don't know how to do it. Also,
if that replacement alternator that you installed in January was a rebuilt
one, it wouldn't be terribly surprising for it to fail after a few months.
Sorry if I didn't answer your specific concern. Your language is difficult
to comprehend.