My first winter (range experiences)

Short answer: Yes and Yes it gets worse.

Long(er) answer: The car will use a relatively huge amount of energy if it has been "cold-soaked" but once you are underway and the systems are at operating temperature, the energy consumption will drop to near summer levels. I will sometimes make a 200 km or so trip in one haul and the initial big spike plus the long cruise at "normal" consumption levels will average out to around 10 or 15% above what I would see in ideal summer conditions. On the other hand, if it's Saturday and I am making small trips running errands and so forth, my energy use can be as much as 5 times higher than in the summer. This is because I use big energy heating things up only to let it sit and get cold again, then repeat.

Hope this helps.

For what it's worth, the temperatures you describe happened recently in Victoria. (Yes, we all complained bitterly. ). I typically drive very short distances, like 5 km at a time. When doing that, I'll see figures like 400 Wh/km. It takes a lot of heat to warm the cabin up! From roughly 0 C to 20 C at an outside temperature of 0 C takes roughly 3 kWh, or 15 km of "rated range".

If you want to avoid charge/discharge cycles, and extend your range, pre-heating the car while it's plugged in is a very good idea.

(You think this is bad in a Model S, try it in a Leaf! 10% of the battery capacity used up just to heat the cabin. That's a lot of overhead.)

PoweredByRain said:

If you want to avoid charge/discharge cycles, and extend your range, pre-heating the car while it's plugged in is a very good idea.

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Yes, and also what I do is try and time my charging session so that it ends just before I leave. That way the battery is warm from charging and you don't have to waste power warming it back up again (either shore power or battery power if unplugged).

Doug_G said:

I completely agree on the first part, but you should be aware that "near summer levels" can mean "80% of summer levels" in very cold conditions, e.g. -20C, and it gets worse as it gets colder. The effect is primarily due to the density of cold air. (On the bright side, drafting trucks becomes even more effective at colder temperatures.)

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Yeah, you're right. I was thinking of, say, -5 to -10 conditions where the energy use starts out high, THEN levels off to near summer levels so that the OVERALL TRIP is maybe 15 or 20% higher than summer.

At super cold (Ottawa?) temperatures, other weird things happen too. The first time I pulled off the highway at those temps, the steering was really stiff as I turned sharply at the end of the off-ramp. I assume it's because there's no ICE up there to keep the power steering equipment warm. Sometimes re-gen limits (and even power limits) NEVER go away.

FrozenCanuck said:

Questions:

1. Does this seem to jive with what others are getting?

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(Don't let the Texas fool you)

When it is freezing here, and I park outside, I lose about the same you do. I cannot speak for -20, but I lose about 8 miles (~13km) per work day - a work day being about 9-10 hours. Same with driving.

As long as you are aware of this, no foul. But it did catch me once by surprise in 2012. Right before new years - the first time I experienced it.

WJ

I don't have direct experience with Model S, but something I've finally figured out from my Roadster, is that when thinking about cabin heating, it's better to think of that as a constant power draw, rather than a % change in energy draw over the trip. The reason being that when the cabin heater is on, you're drawing electricity at a reasonably constant rate, WHETHER THE CAR IS MOVING OR NOT. The % of draw when not moving is huge (roughly 100%), and when cruising on the freeway, very low.

That constant draw is also why I think the Leaf gets bitten so hard. In the Roadster, I figure it's about 2 kw (6 amps at 375 volts), or a reduction of 6-8 miles of range per hour that the cabin heater is operating. If I'm driving 60, then that's a 10% reduction in efficiency. But if I'm driving 20 in traffic, now it's more like 33%.

Hence the importance of thinking about cabin heat as a constant draw, rather than something that alters with how you're driving.


It's interesting to me how much about energy efficiency that we learn about as we drive electric vehicles. I know way more in the last couple years from the Roadster, than 20+ years before with the gas car.

Judging ranges in various conditions can be rather tricky, particularly if the trip includes significant climbs. The most dramatic differences that I have seen to date are on trips from Merritt, BC to Kelowna, BC over the Connector.

In the summer (20C and dry roads) the 75 km climb from Merritt to the Pennask summit uses 125 to 130 km of rated range. The drop from Pennask summit into Peachland adds 20 km to the rated range. The entire 135 km leg from Merritt to my home in Kelowna costs 130 to 135 km of rated range.

Turn down the heat to -15C, add winter tires, and a skiff of snow in the area around Pennask summit, and the Merritt to Pennask leg costs 150 km of rated range while the drop into Peachland adds only 10 km to the rated range. The 135 km leg from Merritt to home ends up costing 180 km of rated range. That's 35 to 40% more than in the summer. And that's in rather good (winter) conditions at a 10 km/hr slower speed.

This reminds me of a question I've been meaning to ask:

How bad is it to just get in a cold-soaked Model S and go? I know that such behavior can be hard on ICEs if you don't let them warm up first.

Obviously, there will be downsides to doing this (limited regen and power, cold seats, etc) but any risk of drivetrain or other serious damage?

Sometimes I forget to pre-condition the car before I need to leave.

I'm talking real winter too (-15 to -30C).

Mayhemm said:

How bad is it to just get in a cold-soaked Model S and go? I know that such behavior can be hard on ICEs if you don't let them warm up first.

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Because the car will limit power and regen, I don't see a problem. The worst I would expect is that if you turn on the defroster full blast, you'll crack the windshield.

Doug_G said:

I've jumped in a cold soaked car and drove away many times. No regen and substantial power limits, as expected. Otherwise no issues whatsoever.

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The effect of "no regen", of course, is increased brake wear. Whether this makes a big difference or not, I don't know, but I do know that during the summer I pretty much use the brakes only to slow from 8 km/h to 0 !