Nice experiment man! Don't forget to write down the results you get for yourself and for public knowledge as well 
Specifications usually mention 0 deg C as a minimum, because equipment is not tested below that, but this doesn't mean it won't work. Maybe you can even give feedback to the manufacturer saying that you tested it for X time and worked / did not work.
As for your cables, others said as well, look into them. Burned cables are no good. Also, 4A/mm2 can be taken as the rough measure on how much current you can push through a copper cable. Don't go above it when operating continuously.
Specifications usually mention 0 deg C as a minimum, because equipment is not tested below that, but this doesn't mean it won't work. Maybe you can even give feedback to the manufacturer saying that you tested it for X time and worked / did not work.
As for your cables, others said as well, look into them. Burned cables are no good. Also, 4A/mm2 can be taken as the rough measure on how much current you can push through a copper cable. Don't go above it when operating continuously.