[G.A.S.]

the proper method for testing a battery is to fully charge and then do a load test.
testing the voltage alone after a charging wont tell you a thing.
After purchesing this batterey did you fully charge it before instalation? Alot of folks will buy a batt and just throw it in the vehical and go.
Not really recomended. Shelf life for a battery is good but they need to be ( re-juvenated )charged, given a kick in the ars to make the electrolite work.
Start from scratch, fully charge the battery for a good 24 hours and then have a load test.
this will assure you that is one possible problem out of the way.