Narrative:

While in good visual conditions above a solid overcast; the alternator went offline. Attempts to reset the alternator would work for a minute or two; then the alternator would go offline again. Decided to divert to ZZZ to preclude potential loss of navigation and communications upon battery exhaustion. Approach controller offered ZZZ1; as it was directly ahead; but the ceiling was lower (OVC009 vs MVFR) and a high descent rate would be required. The controller greatly assisted by providing information such as airport conditions and runway availability that I could have obtained myself but at the cost of time and increased workload.I recently equipped this aircraft with a gtn-750 GPS and aspen efd-1000 pro. I also fly with a tablet that runs garmin pilot. These enabled me to easily determine my position relative to nearby airports and rapidly prepare the ILS approach. While the controller provided radar vectors; the large GPS display showed clearly how I was approaching the localizer course. The tablet allowed me view the approach plate without fumbling for books of plates in my flight bag; I had not anticipated a landing in [this state]; and would not have had the northeast-4 book at the ready. During the approach; presentation of the aspen minimized the workload associated with integrating the attitude indicator; airspeed; altimeter; and localizer/GS indications by displaying it all in one instrument. Further; I recently installed an edm-900 primary engine monitor. It provided very timely alerts to the low bus voltage situation that signaled the alternator failure (the factory 'altitude' failure light on the piper panel is rather dim and not always in the primary scan). Although I initially considered the device a bit of a 'splurge'; I now feel it greatly helps monitor an aircraft's systems and likely alerted me to this condition much earlier than I might have otherwise noted. I doubt many private pilots have given much thought to how long their avionics will run after an alternator failure. Given that my ammeter generally shows about 28 amps and 12 volts; and the battery is rated at 28-30 amp-hours; that's at most an hour. Probably less given a delay in recognizing the problem and attempts at restoring alternator function. Reviewing the flight track on flightaware I was surprised to discover that it took me about 20 minutes from the time I decided there was a problem to having wheels on the ground. I think this is an area that should be emphasized during instrument training and instrument proficiency training.

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Original NASA ASRS Text

Title: PA28 pilot reported an alternator failure while flying at 7;000 feet above a solid overcast and elected to divert before the battery was drained. He praised the Controller for his assistance and the importance of modern avionics that he had recently installed.

Narrative: While in good visual conditions above a solid overcast; the alternator went offline. Attempts to reset the alternator would work for a minute or two; then the alternator would go offline again. Decided to divert to ZZZ to preclude potential loss of navigation and communications upon battery exhaustion. Approach controller offered ZZZ1; as it was directly ahead; but the ceiling was lower (OVC009 vs MVFR) and a high descent rate would be required. The controller greatly assisted by providing information such as airport conditions and runway availability that I could have obtained myself but at the cost of time and increased workload.I recently equipped this aircraft with a GTN-750 GPS and Aspen EFD-1000 Pro. I also fly with a tablet that runs Garmin Pilot. These enabled me to easily determine my position relative to nearby airports and rapidly prepare the ILS approach. While the controller provided radar vectors; the large GPS display showed clearly how I was approaching the localizer course. The tablet allowed me view the approach plate without fumbling for books of plates in my flight bag; I had not anticipated a landing in [this state]; and would not have had the NE-4 book at the ready. During the approach; presentation of the Aspen minimized the workload associated with integrating the attitude indicator; airspeed; altimeter; and LOC/GS indications by displaying it all in one instrument. Further; I recently installed an EDM-900 primary engine monitor. It provided very timely alerts to the low bus voltage situation that signaled the alternator failure (the factory 'ALT' failure light on the Piper panel is rather dim and not always in the primary scan). Although I initially considered the device a bit of a 'splurge'; I now feel it greatly helps monitor an aircraft's systems and likely alerted me to this condition much earlier than I might have otherwise noted. I doubt many private pilots have given much thought to how long their avionics will run after an alternator failure. Given that my ammeter generally shows about 28 amps and 12 volts; and the battery is rated at 28-30 Amp-Hours; that's at most an hour. Probably less given a delay in recognizing the problem and attempts at restoring alternator function. Reviewing the flight track on FlightAware I was surprised to discover that it took me about 20 minutes from the time I decided there was a problem to having wheels on the ground. I think this is an area that should be emphasized during instrument training and instrument proficiency training.

Data retrieved from NASA's ASRS site 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.