[craggle]

Have you got a multimeter?

If so set it to measure amps and connect it inline with the battery and the battery lead. With everything off it should read zero amps (unless you have a radio in which case it will read a few milliamps)
If you get a reading try pulling the fusses out one at a time and see if one makes a difference. If the fuses make no change try disconecting the leads to the alternator.

Dont try turning anything on with the ammeter connected unless it is designed to go to a high amperage. My one is only rated to 10amps max.

Craig.