Coming home from Oshkosh this August, we climbed to 11,500, VFR direct Gary, Indiana, and then to Lunken (the Gary “jog” allowed us to hug the shore of Lake Michigan). It was a beautiful night, and we were smoking — the GPS indicating 180 knots groundspeed as we flew along the Chicago lakefront. Even though we were well above Chicago’s airspace and the weather was great, the retired airline pilot snoozing in the back seat woke up and opined that maybe we should be talking to somebody. It’s against my principles to talk to anybody when you don’t have to, but I also believe you’ve gotta keep everybody riding in the airplane happy. So we called Chicago Center and squawked the code we were given, but even though the “reply” light was blinking, the controller wasn’t picking us up. He told us to “ident,” and when I pressed the button, the transponder died, the cockpit lights dimmed and the Garmin 430 went off the air. But the KX-155 still worked, and we were nearing Gary, so I told Chicago we’d cancel the VFR radar advisories … thanks and goodbye! I tried resetting the master switch and the circuit breakers but saw the ammeter was showing a discharge. Thanks to my vast store of electrical expertise, I intuited that the generator had failed and whatever was working was running off the ship’s battery. So I turned all the radios and lights off except a Garmin 696 mounted on the panel and plugged into ship’s power. My rationale was to let it use up the ship’s battery, if necessary, so there’d be enough internal battery power in the box to get us home on this very black but very beautiful night.