The needle pegged at "C" indicates current is flowing to your battery, assuming the meter is working properly. Disconnect the +ve terminal to the battery, does the needle stay at "C"? If so, your meter is toast. If the meter needle goes to mid point, then current was definitely going through the meter but not to the battery (the only thing that can send current to the battery is the alternator/generator). If this is the situation, then I think you have your ammeter terminals reversed and a heavy current drain somewhere, possibly a short.
