In the Antarctic winter batteries are always a problem. They get too fast too cold an loose a lot of capacity.
Thereforei rebuild 2 batteries adapters for my GoPro and my Canon EOS camera, to be able to use DC Power from 9 until 30 Volts or connect a 220V adaptor.
The GoPro worked really well with a 12V car batterie 6 days at -40C outside. the chassi isn’t real water resistant, there is a small hole for the cables but its small enough that snow or snow drift dint get in…
Be careful! You need to use Fuses for incoming and outgoing Power cables! In my case i used on the Camera side 500mA F (Fast characteristic) Fuses, what worked very well for my needs.
Please consider, i cant take responsebillity what you are building or doing with you camera gear. This side should be just a help to get idears whats possible to build.
If anybody need help to rebulid somethink like this, feel free to contact me!