Video camera power

UPDATE:- So some good progress with powering the device with original small battery and a 18650 supplying 5vdc through a cheap booster.  This time the camera functioned till i removed it from freezer after 2hrs20. I was able to still control all functions and stop the recording. Upon checking the sd card had data for all the time span as well.

UPDATE:- Ok so mixed results. Under 18650 power i managed just over an hour before the camera looks to have stopped writing to the SD card. It was still showing LED wise that it was recording but data stopped being written to the card after 1hr 17. Trying in the freezer this time it would seem that at -28Cish the battery was still reading 4.15volts. Condensation was a factor and think might have caused a few issues with recording. Going to rerun tests and see what results are this time.

So with the video cameras we are looking to use they are normally powered by usb 5vdc and only have a tiny battery for things like powering the clock and keeping the system alive for a few minutes after power is pulled. the battery actually within the make and model we are using is only 180mah. First job was to split the camera apart and see the location of the battery and figure out how we can power it for longer with out having to supply 5vdc through the usb socket. The pictures below give an idea of the setup in taking apart and also the battery itself. It was easy once i figured out the first step.

Once i had the camera open i was able to desolder the existing battery and connect up to a bench power supply. From this i was able to supply a stable 3.9volts to the camera and see what power drain detected in the different modes. Camera standby 20ma Camera record screen on 30ma Camera record no screen 27ma this suggest that a 18650 battery would be a good power source for extended records times. The next step is to test to see how well it can operate at low temperatures that it might experience. One positive is that we can separate power source so worse case a hand warmer can be used to keep power source warm while camera is external.