Question about battery efficiencies and cold weather

Well we made it though the shortest days of the year here in the Chicago area and Tempest battery seems to be holding up well with only being exposed every 4 days to about 2 hours of direct sun. The question now is that we are heading into stretches’ of below zero days if the weather patterns hold up from previous years. What is the efficiency of the batteries in the unit under these conditions?

The Tempest uses a LTO battery and they are pretty stable regarding temperature range

that is the normal range, outside they still work just a bit less efficient.

Thanks for the info…it’s good to see the battery designs are for Exstream temperature ranges.