According to the pilot, during the preflight inspection he noted the battery switch was in the ON position from two days prior and the battery was depleted. He had line personnel from the fixed based operator help jump start the airplane, which started easily, and he spent 20 minutes on the ramp setting up the avionics and preparing for the flight. He checked the voltage and “assumed the battery was accepting charge from the alternator” and elected to depart on the flight. About 10 miles into the flight, he noticed that the panel lighting was dimming, and the avionics turned off. The pilot returned to the departure airport and while enroute, he noticed the alternator circuit breaker was popped. He reset the circuit breaker and power was restored to the avionics. While circling over the airport, he was cleared to land, and attempted to lower the landing gear, however the alternator circuit breaker popped again, and the avionics powered down. The pilot performed an emergency hydraulic dump to lower the landing gear, however, the nose securing bar, which was used to lock the nose gear in the down position when manually extending the landing gear, was located out of reach in the back of the cabin. The pilot asked the tower controller if the nose landing gear was down, and the response indicated that it “appeared to be down.” The pilot landed the airplane, however when the nose landing gear touched down it collapsed, and the airplane slid about 500 ft, resulting in substantial damage to the fuselage. The pilot reported no preimpact mechanical malfunctions or failures with the airplane that would have precluded normal operation.