Is the battery's built-in heater enough?

[taxesarewaytoohigh]

We are attempting to design and build a solar system for our small off-grid house in Wisconsin that will allow us to leave for several weeks in the deep of winter when the temps can be expected to drop to -35F or lower. The plumbing can be drained, and we would leave the building unheated. There really wouldn’t be any load on the battery. Our son (also off-grid) lives close enough to brush snow off the panels if needed. The obvious answer would be to put the battery in another location, but we’re planning that this will be our only home, at least for a few years.

We are considering using the EG4 6000XP all in one inverter and an EG4 Indoor Wall Mount 48v 280AH 14.3KwH LifePO4 Battery, which has a heater. The utility area with the battery and inverter is about 8' x 12' above grade, adjoins the living area, and is well insulated. We plan about 2.5Kw of solar.

We are assuming that there will be at least enough PV power generated to run the battery heater if we leave the PV array, the inverter / charger and the battery turned on. Is that a safe assumption?

Would we be endangering our system in some way by leaving it unheated and letting it heat itself from the PV system?

Obviously, there would be enough electricity available to put some heat into this room.... what is the least risky way to do that unattended?

Or should we consider a small direct-vent propane heater for the utility area?

 

[blackbear199]

no expert but looking at the specs the battery also has low temp cut off it should be safe even if the heater should fail or not keep it warm enough.
worse that should happen is the bms shuts it down untill its within specs to take a charge.