I've never doubted them whatsoever, but yesterday they came into play. We (me and my CFI) flew underneath a Bravo shelf to land at a Charlie (KSFB). Daytime flight on the way over and we were intending a nighttime flight for the way back. I'm in the middle of my XC's right now as well as about to get into night ops. So we did some dead reckoning and pilotage on the way over with a lot of focus on the radios. Flight over was great. We parked, got out, actually took the crew car (nice Mercedes) and picked up my CFI's daughter for the return flight. Got in the plane, going through the Startup Checklist and one of the early items is turning on the alternator and watching for positive charging to occur on the ammeter and... nothing. We tried a few more times and shutdown and restarted again - nothing. Being it was a night flight returning home (45 minutes), we called it. My wife ended up driving all the way over and picked us all up and back home we went. Great wife! Long evening/night! I did have a backup radio in my bag and me and my CFI both were running Foreflight with a Sentry... so there were some options but nothing worth taking a chance on. Great training flight!