The IMA cells will have strong internal resistance when extremely cold and will take a while to warm to become fully functional.
The SoC was 19-20bars on mine with forced charging at 4 bars after startup in the extreme cold i.e. -20C region. The 12V starter activated; coincidentally, I thought I bumped the key on ignition that day due to shivering. lol
After a brief warmup to get oil circulating etc, and soon on the road, Assist and Brake Regen were limited, gradually increasing yet held back from full function until the IMA battery cells warmed internally from light use, and externally via cabin temp air that circulates through the IMA battery case. The full range of operation came back after exercising the pack up and down some hills and after that forced charge was gone and it was maintaining 19bars.
Moving the seatback in front of the IMA air inlet forwards to allow better airflow may help warming.
After the -20C ordeal, what with all the charging at full SoC, it seemed to have acted like a tonic. The battery seems better now than before.
Other measures taken to enhance drivability in cold weather are as mentioned use of a
block heater for warm startup*;
cardboard placement in front of the radiator to preserve engine/cabin heat;
warm air routed to intake for more lean burn;
relocation of the ambient temp sensor to promote auto stop;
good grippy LRR winter tires to stay on the road at expense of fuel economy; and such.
*I haven't found need to use the block heater to start the vehicle as a necessity, but warming the coolant makes the windows clear right away for safety sake as well as saves some fuel.
Also to keep the windows clearer in extreme cold at highway speeds I don't use the cabin air recirculation feature of the climate control any more than i have to. I find in those conditions the windows stay a bit clearer of fog with the drier fresh outside air when underway on a long trip.
edit: hope it doesn't get this cold but careful not to hit a really cold windshield all of a sudden with a blast of hot air under extreme conditions to prevent cracking due to thermal expansion.
Extreme Cold Weather Driving???
