Single Pilot in a single engine aircraft reported a complete electrical failure. The pilot used a handheld radio and contacted the ATC tower and had them visually check the landing gear was down. A successful landing was accomplished.

Narrative

I was performing a maintenance flight check on a Piper Aztec 23-250. Performed an exhaustive pre-flight; and even asked maintenance to add pressure into the right main landing strut as the aircraft was not level. Performed an exhaustive run-up; including cycling through the alternators' circuit breakers; and the ammeter selector. All was good. I flew 1 take-off; pattern; and normal landing on Runway XX at ZZZ. Full stop; taxi back.I performed a second run-up. I took off from Runway XX to the NE practice area; climbing to 10;500 ft. There; I flew clearing turns; steep turns; and then slow flight. While in slow flight; the GPS screen suddenly went black; followed by the JPI; electronic propeller RPM indicators; CHT indicators; radios; transponder; and all electric equipment in the span of 30 seconds. I recovered from slow flight; checked the circuit breakers; took note that there was no special smell in the flight deck; cycled through the alternators' circuit breakers. Nothing changed. I then reached for my hand-held radio; and plugged my headset to it. I used foreflight on my Ipad to confirm my situational awareness as I was purposefully losing altitude and head direct to ZZZ. I made continuous calls to ZZZ Tower until I finally was able to establish communication with them; and informed them that I was with a full electric failure and without comms; talking to them through a handheld. I requested a low approach as my landing gear indicators were inoperative without electricity; though I did have the nose wheel confirmation in the mirror; and know that the hydraulic pump is driven by the left engine; and that I could always use the emergency pump and/or the CO2 cartridge; but figured that obtaining a confirmation from Tower regarding my landing gear was still safest. I flew 100 ft. above Runway XX; then performed left-close traffic pattern for a normal landing on Runway XX.