[criddell]

Your Psion 5 battery numbers sound about right. In comparison, a new Macbook Air can play 18 hours of video on a single charge. Thirty-five years ago, the Radio Shack Model 100 could run for that long on a set of 4 AAs. It should be possible to make an ultra-low power device that can run the Psion 5 apps (ie simple apps) that can go for weeks on a single set of batteries or charge.

I really miss the Psion 5 / Radio Shack Model 100 / eMate class of devices. I think they are still better in some respects than modern Android-phone-with-a-keyboard devices.