On July 25, 1993, at 2130 eastern daylight time, a Cessna 177RG, N185OQ, registered to Steven K. Weber of Greensburg, Indiana, and piloted by a commercial pilot, while executing a VFR approach to runway 18 (3,433' x 40' dry/asphalt), collided with a power line. Visual meteorological conditions prevailed at the time of the accident and a IFR flight plan was filed. The personal flight was operated under 14 CFR part 91. The aircraft sustained substantial damage. The pilot and three passengers reported no injuries. The flight originated from Talladega, Alabama, at 1800. Enroute to Greensburg, Indiana, the pilot encountered a slight discharge in the ammeter. While trying to trouble shoot, the pilot observed a larger discharge when turning on the landing light. The pilot stated that he turned off all unnecessary equipment, cancelled IFR and continued VFR to Greensburg. With diminished electrical power, Don Yager,a commercial pilot, assumed command for the landing. According to the pilot, as the landing gear was placed in the down position, the battery voltage dropped and the lights dimmed. The crew elected to continue hand pumping the landing gear into the down and locked position. On final approach for runway 18, Greensburg-Decatur County Airport, the right main collided with a power line. Due to impact damage of the right gear down lock mechanism, the right main landing gear was unable to be locked in the down position. The pilot declared an emergency and diverted to Columbus Municipal Airport. With the nose wheel and left main gear down and locked, and the right main in a trail position, the pilot made and uneventful lading on two gear. The empennage and tail surfaces sustained substantial damage.