I have a 1991 300SE. As I was driving home last night the lights dimmed and I lost nearly all electrical power but the car ran fine. When I got home and shut the car off, it would not start. This morning, it started right up with full power but 5 minutes later the lights and power dimmed. No restart after I shut it off, but 5 minutes later it started again with dim lights and low power. Any ideas what this could be?