A 3.7V type 18650 battery with in-built USB recharger...? How cool is that? It seems it's only slightly longer (67mm instead of 65) but has a great capacity. Maybe such a battery can be tweaked to connect to the USB of the board and have it charged while connected.
I would not suggest those, the highest 18650 capacity is 3400mah from phillip NCR cells that are pretty expensive. Those are probably some 14500 cells inside a 18650 body with a usb lipo charger, probably a 900mah actuall capacity.
Canobi: I'm also having trouble with converted audio as well. For some reason the WT software won't accept anything above 8Khz, anyone else had this problem?
thats weird, i just open my wavs in audacity, manually change the project rate to 22000 hz and save the new wavs