I've had two different items on my battery bus experience fuse failures. First was the tach transducer, which I have since re-wired and moved to the main bus. Today before going flying (2nd flight) I discovered I had no alternator current, and found that the 5A fuse on my alternator field wire was blown. This fuse was in the Battery bus. Since I had flown once and done several engine runs with no problems, I identified that the one thing I had done between the two flights that might have caused this is that I put my charger on my battery. Is it possible for a battery charger to induce some transient current on the battery bus large enough to blow a 5A fuse??