LiFePO4 and temperatures specifically COLD and FREEZING

One of the biggest problems with using LifePO4 cells in an unheated power shed is temperature stability. More from the cold than the heat in my climate, although heat can also be a problem. A few months ago I got nearly 600AH of cells at 51.2 volts (48 volt system) I've been dragging my feet on hooking them up because they can be stored at cooler temps but they can NOT be charged below freezing. Well of course we are in the coldest Jan. in years right now as I am contemplating how to keep my new batteries from freezing when I do hook them up. Then a couple days ago I had the thought to use water pipe tape / cable that turns on at 38f and off 50f.



So I thought I'd post about here incase anyone is having the same or similar issues.  

I'm not sure how much space the batteries take up, but I know people that keep their well house above freezing by putting a 60w incandescent bulb in a well insulated small space.