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Batteries and sub zero temperatures

The battery will remail at appr 20 degrees Celcius at all times, the internal build-up of the battery will ensure this, I am told. However I wonder what will happen if I leave the car outside in sub zero temperatures for a prolonged amount of time. I am from a country where we regularly have -20 C for months on end. Will the battery ensure satisfactory temperatures for how long? How much juice is used to keep the internal climate of the battery in sub-zero conditions?

I know there have been tests in sub-zero climates, but I have heard little or none at all about this. Any suggestions on where to find relevant information?

This is a concern of mine, too. I know that they did some testing, but from what I could glean, it only was for about three or five days, and I'm not sure how much of that time was below zero. My plan is to keep the car plugged in as much as possible during these bouts of cold. (It will not be housed in a garage.) My concern isn't so much about the battery, except that I know range will be affected, but more about the touchscreen and its functionality in the cold. While the battery has protection from the cold, I don't know about the touchscreen that makes the entire vehicle operational. I'm sure this is all well taken care of, but at the same time, I remember the dire warnings of not keeping digital equipment exposed to the cold. Please, someone appease my fears--without getting too technical; that just goes in one eye and out the other!

My take on this is:

In cold weather the touch screen may be slow or even unresponsive until the car interior warms up. The actually functionality behind the screens should be fine. In the Prius with it's 13 or 14 ECU, that's how it's touch screen works and the Model S is just a bigger touch screen. In fact, the Model S should actually work better because of the heat generated during charging and the heating control that you can do through the Tesla app. You may even be able to keep the cabin at 18C all the time it is plugged in.

If you left the car outside in Grande Prairie or Saskatoon in February without being plugged in for days at a time there could be a problem, but I'd expect it to be with the battery rather than the electronics. Plugged in there really should be no problem with the battery or the electronics.

jerry3;
Rather supprised to hear of any electronics "slowing" from cold. Circuitry works better and faster in cold, right down to liquid nitrogen or helium temps, AFAIK! Maybe display elements are different, as they must emit thermal photons.

The electronics are fine in cold, it's the touch capacitance portion that doesn't register as well in cold temps (or through gloves :P). It shouldn't be too hard to program the internal temperature to be maintained above the freezing point, especially if the car is plugged in overnight (as it should be IMHO).

Even without being plugged in, the battery should be able to maintain the battery temperature for a couple weeks at least IMHO. The climate controls don't eat near as much power as the motor does afterall.

Brian,

Like Vawlkus says, it's the display that's the problem. Pressing a steering wheel button to change the screen can take a few seconds when cold. No doubt the ECU is wondering when the display is going to get with it.

Vawlkus,

-30 or -40 cools things down pretty fast. In the Land-Rover Series III you could let the engine idle to run the heater while you were waiting, but a skidoo suit, plus the heater, was really needed to be comfortable.

Regarding cold and electronics, the main issue is circuit boards and different expansion coefficients. Metal grows and shrinks in temperature changes, so that loosens things up that are meant to be rigid. I wouldn't worry about it, though. If you're *really* concerned, toss a dark blanket over the dashboard when you park it. Or, since you are parking it outside, get a car cover for it. You could even store it in the boot.

@Vawlkus Even without being plugged in, the battery should be able to maintain the battery temperature for a couple weeks at least IMHO. The climate controls don't eat near as much power as the motor does afterall.

I wonder how long it takes for batteries to cool down after heated to driving condition without needing the additional heating in lets say -20C. It is after all a rather big mass of liquid-cooled instead of air-cooled heated material which should be insulated quite well. Not weeks for sure, but it could be several hours before it would need any heating. I have no idea about the level of insulation against heat loss thru the bottom of the car though.

If it is several hours, then cold temperature should not cause any extra kWh loss in lets say grocery shopping after the initial heating has happened.

The battery heaters and coolers function whether the car is being driven or not. If the battery starts to get cold, the heaters come on to keep it warm. Same thing if the battery gets to hot. If the car is plugged it, the battery maintenance systems will draw from that. If the car isn't plugged in, then the system will pull power from the battery. Because the draw isn't as high as the motor, just sitting in a driveway a battery has enough power to easily maintain the batteries climate control for days at least, if not weeks.


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