In our fifth wheel, our bank lives in a sectioned off portion of our passthrough bay, with a small furnace vent tapped into it. Additionally, we have a
200W electric heater that is powered by a
thermostatic outlet that turns on at 35F, and off at 45F. This ends up using very little energy - especially since our furnace is usually on low in cold temps. Victron's DVCC now allows you to set a a minimum charge temp, which we utilize as a failsafe.
For the truck camper, the bank sits in an interior cabinet, that is as temperature controlled as the rest of the living area. We monitor temps in there, but even in single digit outside temps have never seen it below around 50F. We could always add a heater like mentioned above, if necessary. The batteries themselves are always a few degrees warmer than ambient since they're actively being discharged (or charged, for that matter).
Having a low temp cutoff is critical if they're sitting on the tongue of your trailer, but otherwise, easy enough to work around. Low temp charging is mentioned often in argument against LiFePO4 on these forums, but I've long dismissed it as people trying to justify why they haven't upgraded or that their lead acid banks are somehow better. More or less the same way I see most posts in gas vs diesel threads.
