Yes the firmware can be update on the SBMS0 you will just need a $5 StLink v2 programer.
I'm just to busy with production of SBMS0 and DSSR20/DSSR50 so I will not have time to work on the software now.
The better the thermal insulation the lower the energy consumed to keep the battery at set temperature.
The US system is fairly hard to use and non intuitive so I will give you the example in metric.
Say you have R10 insulation (US units) that will convert to R 1.76 in international units.
Then U value again international will be 1/1.76 = 0.57 W per square meter per degree Kelvin or celsius the same thing.
That means that a wall that has 1 square meter (about 10.7sqft) with US R10 insulation will lose 0.57W for each degree celsius difference.
So say you want battery at +10C and outside temperature is -10C then there is a 20C delta between one side of the box and the other and if total box outside surface is 1 square meter then 20C x 0.57W = 11.4W will be needed to maintain the battery temperature at +10C while outside is -10C
So let me use a more real example and say you want a 24V battery made with 8 of those popular 280Ah cells.
One of those cells is 205 * 174 * 72 mm so with 8 of them in series say connected on two rows of 4 cells to have a more square battery then size of that will be 205 * 348 * 288 mm
There is some space needed for clamping plates and connections so will round that to 300mm * 400mm * 400mm for the inside of the box (fairly generous I think just to have a bit more rounder numbers).
So there will be 4 sides that are 300 * 400mm and top and bottom 400 * 400mm
0.3m * 0.4m = 0.12m2 * 4 = 0.48m2 then top and bottom 0.4m * 0.4m = 0.16m2 * 2 = 0.32m2
Total area of the box (on the inside but we ignore the thickness for simplicity) is 0.8m2
So from the above example with R10 (US) insulation assuming no thermal bridging and assuming 20C delta in temperature 11.4W * 0.8 = 9.12W
So this box for this 280Ah 24V battery (or maybe 12V 560Ah) with R10 insulation will need 9.12W to maintain +10C inside while there is -10C outside
So say you had a 15W heater with thermostat control that heater will be ON and OFF so that average will be around 9.12W and thus consumption over a 24h period (assuming temperature outside remains -10C for those 24h) will be 218.88Wh
The battery is 25.6V * 280Ah = 7.168kWh so if fully charged at beginning and there is no charge source it can keep itself warm for a full month 32 days.
Now say the battery box is made of of 1" thick wood with about R1 insulation value then heat loss will be 10x larger than with R10 thus you will need 90.12W to maintain temperature so 2.188kWh in 24h and if there is no insulation then with 150 or 200W heat pads it will still not be able to maintain the battery temperature and battery will be drained from the heating element in maybe a day or so assuming it is full to start with.