11.1 volts at the battery when running

[ahlem]

My less than 1 year old battery seems to have 11.1 volts when running as reported on my Foxwell scanner Live Data test.
The battery light is on. The battery light just came on and went off. I ran the Live Data test earlier today and the results showed 13.4 volts and the battery light was off. Is this an indication of a dying alternator or slipping belt? On the freeway at 70mph, the battery light was still on. During one test session, I revved the motor and the voltage went from 11.1 up to 13.4 and the light went off. Any thoughts? The X5 did sit for a bit longer than usual during a two week warm spell when I drove the 335.