Oh the joy that tales of the battery life of the M10 brings to me
There must be some way we can find the Sony design team who are responsible for this machine and organise a meet up where we can all file past them and collectively shake their hands and bow in reverence.
Anyway, I was just thinking the same thing as Stan and wonder if anyone knows the upper voltage limit to the 3V input. The actual voltage of a fully charged 3.2V cell could be around the 4.2V mark so that would need to be taken into account.