Narrative:

While on an IFR flight plan my aircraft suffered a charging system failure. The failure was not immediately identified; and the battery was allowed to drain as a result of this. At roughly the position and time listed above (to the best of my recollection); center identified that my mode C transponder had stopped receiving. I talked to them and they agreed for me to cycle the transponder; which did not change the status. I then attempted to cycle the avionics after talking to them. Upon turning the avionics master back on; the audio panel did not turn on; and the intercom ceased to function. My HSI also was showing a 'heading' flag. Believing that this was a complete avionics failure; I reset my squawk code to 7600. Approximately 5 minutes later; I realized that I was able to communicate two ways; and reset to my assigned squawk code; after explaining the situation. Approximately 5 minutes after that; the volume started fading on the avionics. I then realized the issue was a charging system failure. I switched off the master switch and avionics master; and diverted to my home base airport under VFR. During this time I adjusted altitude between 7;500 and 11;500 for cloud clearance to maintain VFR and to avoid turbulence during the remainder of the flight. Using current on-board sectional charts and a garmin 496 VFR GPS (which had limited battery; so I turned it on sparingly for guidance); I flew VFR to my home airport; attempting to remain outside of all restricted and prohibited airspace. I was able to contact approach and explained the situation to them. The controller gave me a phone number to call upon landing; as he wanted to make sure we made it home and back on the ground safely. I had sufficient battery power remaining in the plane to contact tower; explain the situation; and receive clearance to land approximately 15 miles out from the airport. Upon switching on the electric fuel pumps as part of the landing checklist; the entire electrical system ceased to function. I landed and upon parking called the tower to thank him for his help and explain that the entire electrical system ceased to function on downwind when I switched on the fuel pumps. I called the controller from approach to let him know that we had landed safely; and thanked him for his help and concern. I considered alternate landing options; but determined that returning to my home airport was the most logical option. I had sufficient fuel on board to make the trip with reserves; and that would allow both my plane and me to be back at home base; rather than stranded at an alternate airport. I also had weather data to inform me that the weather between my location at the time and itwould remain VFR for my trip; thus not risking going into IMC without avionics. I was pleased with the response from ATC during this event. They were helpful; understanding; and courteous. Additionally; they showed concern for my safety during the flight.

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Original NASA ASRS Text

Title: A PA23's electrical system failure was not immediately identified in flight as equipment gradually failed. An emergency was declared during a diversion to the reporter's home airport.

Narrative: While on an IFR flight plan my aircraft suffered a charging system failure. The failure was not immediately identified; and the battery was allowed to drain as a result of this. At roughly the position and time listed above (to the best of my recollection); Center identified that my Mode C transponder had stopped receiving. I talked to them and they agreed for me to cycle the transponder; which did not change the status. I then attempted to cycle the avionics after talking to them. Upon turning the avionics master back on; the audio panel did not turn on; and the intercom ceased to function. My HSI also was showing a 'HDG' flag. Believing that this was a complete avionics failure; I reset my squawk code to 7600. Approximately 5 minutes later; I realized that I was able to communicate two ways; and reset to my assigned squawk code; after explaining the situation. Approximately 5 minutes after that; the volume started fading on the avionics. I then realized the issue was a charging system failure. I switched off the master switch and avionics master; and diverted to my home base airport under VFR. During this time I adjusted altitude between 7;500 and 11;500 for cloud clearance to maintain VFR and to avoid turbulence during the remainder of the flight. Using current on-board sectional charts and a Garmin 496 VFR GPS (which had limited battery; so I turned it on sparingly for guidance); I flew VFR to my home airport; attempting to remain outside of all restricted and prohibited airspace. I was able to contact Approach and explained the situation to them. The controller gave me a phone number to call upon landing; as he wanted to make sure we made it home and back on the ground safely. I had sufficient battery power remaining in the plane to contact Tower; explain the situation; and receive clearance to land approximately 15 miles out from the airport. Upon switching on the electric fuel pumps as part of the landing checklist; the entire electrical system ceased to function. I landed and upon parking called the Tower to thank him for his help and explain that the entire electrical system ceased to function on downwind when I switched on the fuel pumps. I called the controller from Approach to let him know that we had landed safely; and thanked him for his help and concern. I considered alternate landing options; but determined that returning to my home airport was the most logical option. I had sufficient fuel on board to make the trip with reserves; and that would allow both my plane and me to be back at home base; rather than stranded at an alternate airport. I also had weather data to inform me that the weather between my location at the time and itwould remain VFR for my trip; thus not risking going into IMC without avionics. I was pleased with the response from ATC during this event. They were helpful; understanding; and courteous. Additionally; they showed concern for my safety during the flight.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.