Originally Posted by Bill Glover
Surely when connected to USB approx. 5V is applied (via the board) to the battery terminals, in order to charge it?
No. The USB connection goes thru a charging IC on the board.
I don't know what happens when 5V is applied to the "special" USB connection (record and charge), most probably thru resistors or a regulator. The battery circuitry is certainly not built for 5V. I haven't traced the "special" connection.