i was driving my van and battery light came on wont start know

Try to jump start the car, if the car starts then I would think its the battery, if not then you may need to look at the starter.

check your altenator

It could just be the alternater belt. Same thing happened to me. I had hit black ice and slid into a curb. The force pushed my turned wheel into my pullies knocking one out of whack. So every time I hit a pothole or even drove through a rain puddle my alt belt would fall off. FYI with the Dodge Grnd Carv it is so much easier to get to the belt and put it back on if you remove your tire & go in that way. Much easier on the manicure too.