It got down to 5 degrees Fahrenheit last night and I'm charging my El-cheapo lifepo4 now at 20 amps..But I keep them under the dinette seat with the door open and an indoor outdoor thermometer laying next to my two batteries,so I can monitor the temp from in the house...
I couldn't replace my truck camper battery with a Lifepo4 unless I moved it inside or put heat to it...The going price for a cheap 100ah lifepo4 battery on Amazon is $319 with a couple just under 300...
Jayco