What happened
During an IFR flight, the pilot identified a gradual loss of electrical power caused by a faulty voltage regulator. Following this failure, the pilot contacted ARTCC to request a change in routing with the intention of landing at the airport.
The pilot reported circling the airport while awaiting clearance. According to the pilot, he received a green light from the ATC tower; however, while on final approach for landing, he received a red light from the tower. In response to the red light, the pilot initiated a go-around maneuver and began a second approach shortly thereafter.
During this second approach, the aircraft completed a gear-up landing. When questioned regarding the use of the emergency gear extension system, the pilot stated he did not utilize the system because he believed he felt the drag of the landing gear during the descent.