I am aware this thread has gone a little off course and developed a heavy "Solar Charger" feel, but hopefully it will be back on course soon.
Meanwhile here is another "Solar Charger" observation, albeit a not very interesting one, this time about charging the device.
While charging using the USB input, the output of the "Gold Solar Charger 2600mAh" battery slowly increases till it hits the maximum charge voltage of the LiPo (around 4.2V at which point the LiPo is fully charged), then something unexpected occurs.
The LiPo charge protection switches out the battery, as it is designed to do, because LiPo cells don't like over voltage, and cant be trickle charged. At this point, we see a sudden *increase* in output voltage.
Within the space of less than a second the output goes from 4.24V to 4.71V, the reason so far as I can tell is that since we no longer have the battery in the circuit, we are now connected directly to the USB charger +5V source via one schottky diode drop.
This would of course mean that if you left the camera running and attached to the nominally 3.7V output it could potentially be fed up to as much as 4.8V, but perhaps more importantly if the charger was unable to provide enough current to run the camera, then the charger might suddenly shut down (or worse still an internal protection fuse might pop in your charger, bear in mind that some USB +5V chargers are limited to 500mA or less, so there is a pretty high chance of this).
If the charger did switch off rapidly, this should simply result in the battery kicking back in, but it would also probably cause a fairly abrupt transient spike and or dip in the supply, perhaps enough to crash the camera or maybe cause it to shut down unexpectedly.
This problem would also affect any purely "solar panel connected to a LiPo" setup, and probably it would be worse, since the panel is not going to have a nice clean steady +5V, and furthermore it would be unlikely to be able to drive the camera directly (unless it was a whopping big panel).
We have a situation where once fully charged the LiPo and solar panel could start to oscillate on load, with the battery switching out, the load transferring to the panel, the panel overloading, the battery switching back in and so forth.
I suspect therefore it would be a good idea to add a suitable smoothing capacitor across the input to the camera to avoid potential issues. Furthermore if your solar panel is capable of producing much more than +5v in direct sunlight you would have to feed the battery charger through a regulator, or we are back to fighting with the magic smoke.


Two completely unnecessary pictures of my multimeter and some assorted clutter.