My car a couple days ago had a voltage drop from about 14v to somwhere around 11. I didn't think anything about it because next time i turned my car on it was back up again. Tonight the voltage dropped and kept dropping. When i got home the guage was at the very lowest point on the meter. I let it run for a few minutes and the car started to stall and then I cut it off. What could be the problem? Do i need a new alternator. I just got a new battery a couple months ago.