chewbears

I just took my lexus to a local shop to have the alternator replaced. Now a month has past and the alternator went faulty. I took it back and they warrentied it out and put another new one on. Drove it home and tested it just to be sure, and with lights and AC on alternator wold read ~12v, turn them off, it would read ~14v. It is currently back with them at the shop and they are looking into potential design flaws in the alternator they are using, or issues with the control module. BUT has anyone experienced this?

Thanks