Jamez wrote:You guys have had yours longer and dug into it further, but on 3 separate occasions I have returned to the car 8 hours later during -16C ambient temperature to have between 2 to 5 km's range lost.
Yes, this was probably because the battery simply got COLDER between those two points in time.
It is a matter of physics and chemistry that batteries do not perform as well as they get colder. Further, there is one thing that performs worse than a cold battery: An even colder battery.
The effect I'm talking about is dynamic
: the energy potential of a battery is not a "static" thing, changing only when energy is explicitly consumed. Instead, as the battery temperature decreases, the car will measure less and less voltage at the battery, compute less energy available, and thus estimate a shorter range. Conversely, if the battery temperature increases between two points in time, the measured voltage will increase, the car will compute increased energy available, and estimate a longer range.
Again, this isn't a function of some absolute amount of energy somehow being "moved" out of (or into) the battery... it is an intrinsic function of the battery just getting colder (or warmer), chemistry and physical properties changing, and the resulting decrease (or increase) in the battery's potential for releasing energy.
Managing battery performance in extreme weather is one of the things that the "GO Time" feature is for... to give the car time (and extra power) to heat (or cool) the battery just before you want to drive, adjusting the battery temperature closer to an optimal level, and improving its performance.