Viking Pilot reported a broken alternator belt caused electrical system failure. Pilot diverted and made a precautionary landing.

Narrative

I completed the purchase of this airplane at XA00 local time this morning prior to departure. I went out for preflight and familiarization with the previous owner then departed for ZZZ. We departed ZZZ1 VFR and picked up an IFR in flight. Approximately 30 minutes into the flight the alternator voltage light illuminated and the engine data monitor showed that I was losing battery voltage. I then requested a diversion to another airport and was given clearance. Within 10 minutes of being on course I started losing avionics capabilities. I [requested priority handling] and squawked XXXX and took emergency action and diverted to the ZZZ2 airport which was 20 miles close. I was able to descend in VMC to approximately 1200 ft. MSL and remained VMC until landing. I had enough electrical power to extend the landing gear and deploy flaps. On landing I had 9.8 volts left on the battery. I was in constant communications with an overhead airliner and I relayed that I was down and safe. I also called ZZZ center on the phone and let them know that I was down and safe on the ground. Post flight inspection showed that the alternator belt had broken in flight. Factors that delayed earlier action is that I only had about 30 minutes of total flight time in this aircraft. I have flown similar make and model in the past however; the instrument package was not the same. I executed the alternator failure checklist per the POH and also turned off equipment not needed to execute the approach and landing. Performance was hindered due to my total experience in this airplane.