Surprise-surprise

[ny_quant]

A new AAA study finds that when the thermometer dropped to 20 degrees Fahrenheit, range fell by an average of 41 percent on the five models it tested… Some EV drivers recently found that range can drop by half when the mercury tumbles into negative territory.

https://www.cnbc.com/2019/02/06/aaa-confirms-what-tesla-bmw-nissan-ev-owners-suspected-of-cold-weather.html

Comments

[misha-b.livejournal.com]

Yes, that shows why accurate comparisons are tricky.

[agasfer.livejournal.com]

One more consideration, completely unaccounted for so far, is that in the cold it takes less energy to recharge the battery. To simplify the model, when the battery is charged, the energy is used to convert chemical A into chemical B (there are several chemicals involved, of course, but just to make it simple); then this energy is discharged into electric current when B converts back to A. If the battery is cold, you still have the same amount of chemical B in the battery, meaning, you have the same amount of energy stored. So why it gives back less energy in winter?

The reason is, if in the summertime the battery is discharged to 100% A and 0% B (ideally), in the cold it stops working at about, say, 75% A and 25% B. So, if you warm up the battery, it can go on discharging to 0% B, but in the cold it just stops working when not completely discharged. However, this also means you need to convert only 75% A back into B, not 100% A, when you recharge the battery again.

Thus, in the wintertime you have to recharge the battery more often but every time you are recharging you use less energy. This leaves the same reasons to use more energy in winter as with the combustion engine vehicles.