I have a '95 M plate Isuzu engined (or so I believe it to be) 1.5 non-turbo diesel Corsa. The car has gradually over the last month took longer and longer for the battery light to go out to the point now where unless you are doing 60mph+ for longer than 10 minutes (i.e. motorway driving) the battery/alternator light does not go out at all. I havent put a multimeter across the battery yet but I was wondering what the chances were that this is NOT alternator related? Or is it inevitable that I will have to change the alternator.