Pilot reported electrical system failure in flight. As the pilot diagnosed the failures; the pilot used a cell phone to contact ATC and request priority handling. The pilot received vectors to destination airport and extended the landing gear using alternate extension procedures. During landing the main landing gear unlocked and the aircraft settled onto the partially extended main gear. The pilot secured the aircraft and waited for assistance in moving the aircraft.

Narrative

During a short flight from ZZZ to ZZZ1 noted the battery light flashing and a discharge light. Turned around and headed back toward ZZZ. Started shutting off unnecessary avionics and then lowered the gear before a possible battery drain and loss of electrical power. The second the gear dropped; the panel went blank. Looked for my hand held and realized I left it on the charger but have blue tooth and a cell phone so called the Tower. Tower cleared me and I requested Tower to visually confirm all three wheels were down. I made a small S turn so they could see on approach and they confirmed all were down. I had full 1;500 PSI hydraulic pressure so gear should have lowered and locked. I also had the electric hydraulic pump so I knew I had to get it down and one shot at it from the main gear pump. Landed as soft as possible but as soon as I touched the brake I could feel the main landing gear move so knew they did not lock. Let off the brakes to keep the mains under me but left brake must have engaged a bit more because I was drifting left. I tried the starter to see if I could 'square the prop' just in case but no power. So allowed the plane to slow on its own hoping it would come to a stop before the turn off. But the forward momentum was too great and was going to run off the runway without brakes and strike the taxiway sign. I tapped the right brake in hopes to turn a bit but couldn't get enough without pushing the right gear aft where it folds toward fuselage. I held off the brakes as long as possible and hit the brakes together and could feel the plane lower as the gear moved aft but stopped before striking the taxiway sign and nose gear just off the pavement. Plane was almost to a stop when the main gear settled -- but not fully retracted aft having pressure in the system. Gear was about 75% to 80% aft but not fully retracted -- So no damage to gear doors; under carriage; flaps; wings; not even the tires where they dragged the last bit at an unusual angle. The nose remained so no prop strike - heck the only evidence of this incident is a small scratch on the left fiberglass strobe light lens housing. Touch up paint! So no damage!I stayed calm through the process and reviewed the emergency procedures in my head with every intent on avoiding an incident and damage. Had just reviewed the emergency procedures only a few days prior thankfully. Don't know what caused the electrical system to discharge so quickly but have already scheduled service to diagnose to determine if it's the alternator and make repairs or replacement as necessary. Obviously the hand held is in the airplane already. After electrical repairs I'm going to charge the hydraulic system and shut off the power while the plane is on jacks to determine if and why 1;500 PSI without power will not lock the gear down and why. In retrospect I could have used the backup nitro system but felt certain the gear was down and locked. After this test done a few times will determine if the backup system should be used with or without 1500 PSI in the main hydraulic system. Going to be 110% sure this never happens again; still very very blessed and thankful. Special thanks to the ZZZ fire department that helped me jack up the plane to get the gear back under the plane -- what amazing guys!