C-177 LOST ELECTRICAL POWER IN IMC. HANDHELD RADIO WAS UTILIZED TO COMMUNICATE; EMER DECLARED; AND FLT WAS VECTORED TO ARPT FOR LNDG IN VFR CONDITIONS.

Narrative

ON THE ABOVE DATE AND TIME I EXPERIENCED A COMPLETE LOSS OF PWR TO THE ACFT'S ELECTRICAL SYS. I WAS ON AN IFR FLT PLAN. I WAS CRUISING AT 7000 FT UNDER THE DIRECTION OF ATC. AT APPROX XA19 I OBSERVED A 'RED FLAG' ON THE S-TEC AUTOPLT INDICATING A LOW VOLTAGE SITUATION. A CHK OF THE AMMETER ALSO INDICATED A NEGATIVE CHARGE. SHORTLY THEREAFTER; I LOST COM #1; MY PRIMARY GNS 430W; THUS LOSING MY PRIMARY NAV AND COMS. I WAS ABLE TO COM ON COM #2 FOR A SHORT PERIOD; THEN THIS SHUT DOWN AS WELL. BEFORE I LOST ALL PANEL COMS; I USED THE GPS 496 HANDHELD TO DETERMINE THE LOCATION OF ZZZ; A TWRED FACILITY AND EXPRESSED THIS TO ATC. I AM NOT SURE THEY GOT THIS; BUT ASSUME THEY DID AS I WAS HANDED OFF TO THE TWR FREQ AT ZZZ. ONCE I WAS IN CONTACT WITH ZZZ; USING MY HANDHELD PORTABLE RADIO; I DECLARED AN EMER BASED UPON THE LOSS OF ALL PRIMARY NAV AND COM EQUIP. THE ZZZ CTLR GUIDED ME TO THE ARPT BY VECTORS AND PROVIDING ALTS TO MAINTAIN. UPON COMING THROUGH THE CLOUDS AT ABOUT 1200 FT; I MADE AN UNEVENTFUL LNDG AND CONTACTED THE TWR FOR ANY FURTHER INSTRUCTIONS. THEY ADVISED THAT NO FURTHER ACTION WAS NEEDED AT THIS TIME. THE PROBABLE CAUSE OF THE FAILURE IS A DEFECTIVE ALTERNATOR.