My battery light is on, and the engine makes a bit of a different whirring sort of sound..

I'm wondering what is more likely.. fried alternator, belt issue or.. something I haven't thought of?

This first started after some soggy weather, which was also effecting my coil and causing misfires. The weather has dried up and the engine is running evenly again but the batter light remains on.

Cheers

 

My guess: slipping belt. But why does it slip? Wear or low belt tension. Maybe the alternator is causing to much resistance. If replacing the belt does not fix it, have the alternator checked.