You can power each camera using an external power pack such as the TeckNet Power Bank 12000mAh external battery power bank, though there are smaller and cheaper battery options available, I purchased mine from Amazon.co.uk which cost just under £17 GBP including delivery. I fitted a Mobius Action Cam to my car and used this power pack which lasts for two days in work hours before needing to be recharged. I also installed a Sandisk class 10 128GB micro SD card which records for days before overwriting the oldest video footage depending upon how long the Mobius is powered up for.
The beauty of the Mobius is that it is so small, so compact, (smaller than a packet of cigarettes) and it's so reliable. You can even buy direct from the manufacturer on Ebay, and they do have a good reputation for after-sales service which is quite outstanding.
I just checked out the Mobius. Looks like a clever and quite stealthy camera. If I can make it run just like a DOD dash camera, connected to the 12V (guess it doesn't pull as much power as a DOD cam?), and have it record for at least 24 hours in a go, this could be the solution to bust the bad guy.
Or do I have to use external power only to power the Mobius?
You say it records for days.. Guess the resolution is very low then? I need continuous filming.