My car had been acting funny for about 2 weeks, the brake and battery light kept blinking when I would be driving. So on Friday night, everything shut down when I was driving, the headlights, the radio and the engine turned off. I eventually got it to jump and took it up to Advance Auto parts, the guy tested it for me and told me I needed a new alternator, so I bought one and put it on right there. The guy came out and tested the new one for me before I left and everything was fine. So today, the battery and brake lights are lighting up again, also my headlights get brighter when I accelerate...any ideas what could be going on before I take it up to the Nissan dealer and fork over some big bucks?