Mitsubishi batteries do NOT like #winter charging!
"Compete charging may not be possible."
A Three day journey to the mountains made me realized some very concerning battery facts, that started from the observation that when the battery was fully charged only hold 38.3 Ah or 83% capacity!
At the time I put the blame on local cold weather, thinking that when I will return to normal temperature all will be well, but it wasn't!
In this 3 days I charged the car 3 times using the 10Ah provided charger. The lowest battery temperature during this period was 3°C. Minimal outside temperature was -2°C with mild winds. I did not noticed any warming of batteries until driving the car although this version of the car is equipped with a drive battery warming system!
Before the journey the max battery amperage was 42.4 Ah, after the journey, the max value that the battery was able to hold was 41,4 Ah! So, 1 Ah drop in 3 days, although the BMU value stayed the same and the charge was done above freezing!
In the owner manual it does NOT say to avoid charging the car below freezing, actually the opposite is presented: "When you have finished driving, charge the drive battery before the ambient temperature falls to -15 °C or lower." and "If low temperature is predicted, even if the drive battery is fully charged, connect the EV charging cable (normal charger). The drive battery will automatically be warmed. The Plug-in Hybrid EV system can be started within 1 hour after the EV charging cable is connected."
If you leave in a cold climate ...
I did some research and found out that lithium-ion batteries cannot be charged below 0°C. Although the pack appears to be charging normally, plating of metallic lithium can occur on the anode during a sub-freezing charge. This is permanent and cannot be removed with cycling. Batteries with lithium plating are more vulnerable to failure if exposed to stressful conditions.
Severe and permanent capacity loss on the order of several dozen percent or more, as well a similar and also permanent increase in internal resistance may occur after just one isolated 'cold charging' event, and is proportional to the speed at which the cell is charged.
Li ion can be fast charged from 5°C to 45°C. Below 5°C, the charge current should be reduced, and no charging is permitted at freezing temperatures because of the reduced diffusion rates on the anode. During charge, the internal cell resistance causes a slight temperature rise that compensates for some of the cold. The internal resistance of all batteries rises when cold, prolonging charge times noticeably.
Avoid charging the Li-ion battery of the Outlander PHEV that does not have a drive battery warming system below freezing!
Charging is indeed possible with most lithium-ion cells, but only at very low currents. At this low current, the charge time would stretch so much that is deemed impractical.