Found an interesting (one-time, i.e. disposable) battery cell the other day at Farnell:
These have the size of an AA cell, but they deliver 3.6V, so they can effectively replace 3 AA cells at once. The voltage is just right – this battery could be used with or without the JeeNode’s 3.3V voltage regulator.
The discharge graph is as follows:
I’ve ordered a few with wires attached to them, so they could be tied directly to the PWR & GND pins of the FTDI connector. Will report back once some “field tests” have been done.
Update – better discharge graph, see comments below.