SR22
Flight Crew Commercial; Flight Crew Flight Instructor; Flight Crew Instrument; Flight Crew Multiengine
Flight Crew Last 90 Days 10; Flight Crew Total 1800; Flight Crew Type 20
Communication Breakdown; Human-Machine Interface; Troubleshooting; Training / Qualification; Time Pressure; Situational Awareness
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Diverted
Aircraft; Human Factors
About 150 miles southwest of ATL our Number 1 Alternator failed. We [tried to diagnose the problem; then] tried to bring it back online without success. Since we still had Number 2 Alternator and had run the checklist with appropriate equipment shutdowns; we elected to continue the flight. We were on an IFR flight plan but were VMC the entire route of flight. We were approximately 50 miles SW of ATL when we were given instructions direct to DALAS; Direct PDK and a descent shortly thereafter from 9;000 to 5;000. At approximately 7;600 ATC asked us to confirm our altitude; which was 7;600. They were showing 10;800. They asked us to shut off the altitude encoding at that time. We complied. A few minutes later we noticed the battery was down to 24 volts from 28 and that Alternator Number 2 appeared to not be charging the battery any longer. A few minutes later ATC became unclear and unreadable. We realized what was happening and at that time the battery failed entirely despite not getting a failure light on Alternator Number 2. We squawked 7600 and due to the time of day and anticipated congestion into PDK; our destination; I elected to maintain VMC conditions and divert west to an uncontrolled field which was 40 miles west of Atlanta.  I broke off the IFR clearance once we lost radio contact and our entire electrical system as I thought it the safest and most prudent decision to avoid potential conflicts with other aircraft and a landing at PDK; which is an extremely busy airport during rush hour time. We continued the flight VMC; entered a long downwind after a quick over-flight of the field to view any possible traffic and wind conditions. We landed without any electrical equipment or flaps as they are fully electrical in this aircraft. We spoke with Atlanta Tracon via telephone immediately after landing to advise what had happened. There was no further discussion or questions asked.
Despite the failure of the No. 1 alternator the pilot of an SR-22 opted to continue the IFR cross country anticipating the No. 2 alternator and the batteries would provide adequate electrical power.  Prior to destination all electrical power was lost and the pilot opted to divert to an uncontrolled airport where he landed safely and called ATC to report the event.