Cold Weather - Battery loses many KM while parked during the day!
I have noticed that my 85KW battery loses 20 to 40+ KM (Rated Range) while parked at work (Not Plugged in) during the day in cold weather ~5 Deg C! I did not expect the battery to lose in the order of 40 KM Rated Range just sitting in the lot with every thing off! What are the continuous loads on the battery when the car is Off? Are there additional items I should be turning off when the car is parked? One day when it was ~12 Deg C I returned to work from a long trip with 75 KM Rated Range remaining => when I came out 6 hours later the Rated Range had dropped to 24 KM... Not enough to get home! (35 KM) I was very supprised and worried, but was able to find a level 2 EVSE about 7 KMs away, so i plugged in for about 90 minutes and had dinner, then went home!
Anyone else experiencing this daytime Rated Range KM loss? Any ideas how to mitigate it? (Other than warm weather or plugging in during the day, which is not yet an option where I work)
Thanks!
Correction to above that is -5 Deg C & -12 Deg C (below Zero)
My car is garaged both at home and work (about 55-60 degrees F), so haven't experienced what you are going through. However, from some accounts it sounded as if the rated range reads erroneously low when the battery is cold, and you actually 'recover' some of it as the battery warms up. I could be wrong; others may have more first-hand experience with this.
I live in Toronto Canada...
I don't believe the car heats the battery when it is Off => It only starts to heat it once you turn the car on. you can see a large peak on the energy usage display when you first start driving for about 15 KM (Please correct me if I am wrong - It would explain for the large KM reduction)
Thanks!
There has been a lot of discusson of this on TMC. The consensus there is that the battery actually does not lose that much range when it is "cold soaked" but the algorithm that calculates remaining range misreads the amount of charge left when it's parked in the cold, and reports a bigger loss. When you drive the car at the end of the day do you notice that the range does not go down as quickly as when leave in the morning? People have noticed that once the car is moving and the battery warms up, the remaining range doesn't decrease as quickly, recovering the a lot of the range that was lost when parked in the cold. What is really happening is that driving warms the battery and the algorithm that estimates range becomes more accurate.
Actually I thought I noticed that the Rated Range was decreasing slower today on the way home (lost 37KM during the day) so as you suggest maybe the Rated Range calculation is misleading when the battery is cold... requires more study / monitoring so I can better judge what is left... don't want to get stuck!
Thanks!
You're welcome and forgive the typos. WE NEED EDIT!
@CurrieG, on the other hand, don't count on the battery recovering range as you drive. If the display indicates that you have 24 km left, and you need to travel 35 km, play it safe and assume the display is correct. You did the right thing by stopping and charging before trying to drive home.
I have noticed a "cold spike" in energy usage for a cold battery that last for 5-20 miles depending on the temperature. once the battery gets warm the rated range will stick until it catches up to the battery usage. I once drove home from work and the range started at 170, dropped quickly to 155 after about 5 miles then stayed on 155 for the next 20 miles, then started going down at a more reasonable slower rate. There are lots of threads with good info that you can find by volkerizing. But basically warm battery good, cold battery bad and prewarming the cabin will not warm the battery unless you are hooked up to a charger.
I have had the same problem (in MI) on the very coldest days, and this was what the NT Times guy had happen as well. I posted it on the Musk response to the NYT article thread. I get the impression that it is disproportionately severe at temps below about 20-25 deg F; it hasn't seemed nearly as bad above that. Not sure if this makes sense from a physics perspective. Unfortunately, Tesla has yet to provide a definitive explanation with technical details that make the issue totally clear. I understand the concept of the battery warming up and the range increasing, but on my coldest trip the regen limiter never came close to disappearing even after 50 miles, so it didn't seem that the battery ever became that much warmer to "recover" the "lost" miles. I'm also not sure if the energy to warm the battery is "extra" to that powering the car or not. If it is, then there is at least some truly lost range from sitting in the cold. This issue is obviously critical in very cold weather when planning only moderate length trips that would ordinarily be well within rated range, particularly when the car will be sitting without charging available and no overnight stop for a charging opportunity is involved. We need some very specific guidelines!
My ICE mileage decreases by about 15% when the weather is 20 degrees F or colder.
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