Considering using the MNPowerFlo16 for an off grid system in a cold location - easily -20°C on occasion in the winter. The spec sheet and manual both say that the battery is heated but there are no details about how the heating system works. Seems prudent to know more about the heating function before jumping in. Is heating active only while the battery is being charged? Or does it attempt to keep the battery warmed up all of the time. The spec sheet seems to indicate a 400-watt heater, that could eat through the 16 kWh battery capacity in short order.
Not sure how this one works, but every other lithium battery bms I have heard of will only turn the heater on when charging if the battery temp is below freezing. That way it doesn't drain the battery since the sun has to be up to charge.
For my own setup here in Wisconsin I have lithium batteries in an unheated room and I built a simple insulated box around them and put in a small AC heater that is controlled by an inkbird temperature controller. It keeps them warm enough all the time for discharging or charging.
Larry
I have some of them in unheated but attached garages in the mountains of Colorado, which can dip below freezing at times inside the garage, but I view the heater more as suitable for that kind of situation (or installing in like Arkansas, where it could get into the 20's or teens maybe a few days a winter). Not for surrounded by -20C all the time. 400 watts (I heard 300 watts) is not very much to keep an uninsulated metal box warm inside if it's that cold around it. I'm not sure if you could put it inside a heavily insulated box or something like that perhaps... to make the 400 watts go a lot farther.
Also, the heater is only activated if the batteries are trying to charge. So, at nighttime, the heater does not run. This prevents bricking the batteries by drawing them out into the heater till they are dead just trying to keep themselves warm... but means that it's possible for them to get below 32F overnight, and thus the charging will be shunted into the heater (at 400 watts) til it warms up above 32F. That means potentially wasting a bit of incoming sun if you have a big array, because it can't heat it with the full array capacity.
If you are grid tied, I would use a supplemental heater to the space, or to an insulated battery box, that can run purely based on thermostat rather than thermostat plus incoming charging. If you are off grid, I would seriously look at your insolation during the cold times and whether you have enough incoming solar to keep the battery warm or not, and potentially adding extra heaters triggered by availability of sunshine to heat them faster when the sun first comes out in the morning, if you do get winter sun. Adding insulation can probably help a lot with total required heat as well (since we can't add insolation.... :P
For my own system, it's off grid, with the equipment all in an unheated shipping container, and it gets down to -20F outside at times, and the current battery bank (Nickle iron) has gotten down to -2F during a cold spell (makes them super squishy in voltage at that temp). When I switch to LFP, I'm going to have to do some really serious insulation, as my winter insolation is well under 1 PSH in December typically -- freezing fog...no sun... Really not sure if it's feasible to keep them warm without a non-electric heat source, but I'll let you know next winter. Thinking like an R-60+ battery box, plus heaters run during the daytime.