Originally Posted by jmdlcar
Why can't the 2 battery be wire in Parallel? Leave the internal and solder 2 wires inside and mount the plug so you can just plugin the external battery when needed for longer record time. That way there no switch and no jumper or no mistake made.You won't have to reset the time.
The voltage mismatch between external battery and internal battery at instant of connection can try to force too much current into the tiny camera battery. While it has an excess current protection circuit, I don't know if it's bi-directional... it's mainly for short circuit protection of the battery. Why risk it?
The best way is to feed +5V USB level power in through the camera USB port, but it seems so many want to bypass it with a single external lipo cell.