Ok...I put a new alternator and a new battery in my car, and now the "gen" light stays on unless I rev it. Like the alternator isnt charging the battery unless the rpms are higher, not just idle. It shouldnt be the alternator, but Im going to drive it to the auto store and get them to check it just in case they sold me a faulty one. Any ideas of why this is happening and how I could fix it?