At 0552 mountain time, a Cessna P210N, N4873K, lost electrical power during cruise flight and returned to Tucson International Airport. During the landing roll, the landing gear collapsed and the airplane collided with a taxiway sign. The pilot was not injured. The pilot said he was en route to Dallas when a light illuminated, indicating that the battery was not charging. After lowering the landing gear and the flaps, the pilot turned the master switch to the OFF position in order to conserve power but apparently did not wait for the green down-and-locked indication. During the landing roll, the left gear collapsed, the airplane began skidding, the right main gear collapsed, and the airplane collided with a taxiway sign.