Keeping LiFePO4 Batteries Warm in the Winter. 

How to keep your lithium iron phosphate batteries warm in the winter.
Lithium batteries should not be charged below freezing (32°F, 0°C) discharged below 0°F.
This is an inexpensive and very efficient solution to keep those expensive lithium batteries alive during cold temps.
12V Electric Blanket:
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12V Power Outlet with USB:
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