Lithium Battery Warming System

I put together a battery heating system to keep my LiFePO4 batteries above freezing so I can charge during cold=weather camping. Basically there are 2 heating pads under each battery connected to an adjustable temperature controller that turns the heating pads on or off depending on the temperature of the battery container (based on a temperature sensor). I set it up so there is a separate heating system for each battery (I have 2 100AH  batteries wired in parallel).  I surrounded the batteries and heating pads with some rigid foam insulation. Testing so far shows that the heating pads do not get so hot that I need to worry about melting anything and the system draws approximately 2 amps when the pads in both systems are actively heating -- heating cycles on and off once desired temperatures are reached.  There is an on-off switch for each system so I can fully shut it down when not needed. Here are some images to show what I did. I will continue evaluating how well it works once colder weather gets here.