Got in to the valver last nite after about 5 mins of driving battery light comes on??? i got a bit further down the road when sum tw*t in a ford ka comes up my ars?? got a little pissed of so put my foot down and left him, then the battrey light went off?? later on that nite went in the car again and it was fine. i started her up this moring to go to work got 10 mins down road battery light comes on???? what is happing any ideas??