Heating lithium in winter

[GlennWest]

I read a lot about batteries with heaters, heating area for batteries. Inverters put off heat. Enough they need fans. Seeing as lithium doesn't off gas, would they supply enough heat to keep battery from freezing temps. Put them close together. 

[Randyretired]

When the inverters are working hard they put off a fair amount of heat.  Enough that I crack open the front compartment on warm days.  My batteries are in an insulated compartment that has some vents to the interior.  The inverter is in the next compartment also vented to the batteries. That seemes to keep them plenty warm enough but I haven't been in temps below 20F.  I put some warming pads under the batteries but so far haven't needed them.  My BMS's also have cold temp disconnect.

[oldjohnt]

Sure Inverters produce substantial heat WHEN OPERATING but computing how much heat and the temp to which they can raise/maintain a certain compartment depends on a ton of factors such as size, insulation, ambient temp, etc. etc. I installed T stat controlled vent fans in the compartment where my batteries and Inverter are stored for cooling but I havent tried to calculate any quantity of heat an Inverter might supply to a given compartment. Thermodynamics was NOT my best subject back in the day lol.

 I've seen gents install T stat controlled pet bed warmers and all other sorts to keep battery compartments warm enough to allow charging Lithium, but the internal automatic BMS controlled heating systems would sure be the easiest solution. A temp controlled "heater" (similar to my cooling vent fans) inside the compartment wouldn't be hard to install...Hopefully the batteries BMS already has adequate low temp cut off. 

 John T