The 250mAh died really fast, so in went 380mAh.  It barely fit in the transmitter, with much coaxing.  There might still be room in the receiver for a bigger battery. 

The 15 year old 580 EX II finally died from some unknown semiconductor, transformer, or capacitor failure.  It wasn't the tube this time.  It no longer charged its capacitor above 5V.  It was decided to replace it with a much cheaper Godox TT685 but still use the home made radio to control it instead of Godox's own radio.

The trick with the Godox is it has an aiming light which turns on when the ID pin is high.  The wireless firmware needed to turn off ID when taking a picture.  Sadly, the aiming light is very short range & has a parallax error at short range but it's better than nothing.


The leading idea for a superior aiming light has been firing the flash at lowest power, once per second, when ID was high.  This would entail a new enclosure with another button.  Expanding the receiver would be better than expanding the camera.

The modeling light trigger would have to coincide with the metering packets so it wouldn't conflict with the flash trigger.