Wow, we need to find another way to heat EVs

[MissT]

Driving in the winter here in Ontario and doing 120kph for maybe half to two thirds of the trip my car Tezlab shows about 68% efficiency.

 

[vanzandtj]

That sunroof insulation might be a good deal - keeping the cabin both warmer in the winter and cooler in the summer. (I assume it's designed to withstand the summer heat?) I never pay attention to view upwards anyway. I don't think I'd want the battery insulation, though. It would further reduce the ground clearance, and increase the load on the cooling system in the summer.

 

[navguy12]

I was going to post about this topic last week after driving from Boulder/Denver area to Steamboat Springs (roughly 160 miles one way with significant elevation changes) in unusually cold conditions for Colorado (temperatures dipped as low as -4 while we were driving). It was our first EV roadtrip (Model 3 LR AWD) in the worst possible conditions and a few things were obvious to me:

- Frameless windows are not helping. Not only I could feel the cold coming through the top of the window frame into the cabin but also as ice started to form on the bottom of the window I could not get the window to close 100% to fully seal the cabin once I opened the door to get out for a supercharging stop.

- Glass roof is not helping either. When I touched the roof from inside it was extremely cold despite keeping the cabin around 68 degrees, all the cabin heat rising up met this freezing piece of glass making the heater work harder just to keep up with the heat loss.

- Wipers are useless without a heating element that a 20k Corolla has. After the first time I had to spray, most of the wiper surface end up freezing and making them smudge the windshield instead of cleaning it.

- I constantly had to direct heat to the windshield to avoid it from fogging and freezing, a heated windshield would have cut down my heater use significantly

- The lack of heated steering wheel is annoying. Yes, I did wear gloves but they are not as grippy as my skin so not terribly safe to drive in slippery conditions with gloves on.

FWIW: after my 6.5 minute test drive of You You's Model 3 in Jan 2018 at -23c temps, I knew I would have to come up with a standard operating procedure for the HVAC whilst driving my (then future) TM3 in the winter.

With two winters under my belt, this is how I keep things set up:

• airflow to windscreen, floor and main vents aimed at upper side windows,
• fan speed to one (1),
• fresh air only,
• AC off, and
• temperature set to 19C.

Works like a charm, although the sunload sensor will sometimes insist on making the system dump cold air into the cabin to chase the set point (I have a digital thermometer sensing what comes out the floor vents to inform me of the amount of heat being pushed into the car).

 

[Fast32]

I make a once a year trip from Iowa to Az. approx. 1600 miles. this starts at the end of Oct. and I return early Dec., so Day time temps vary from 50s F to about the low 30s F. I have a Signature "S" 85 in near perfect condition and the battery is still within 6% or so.
Reading all of the interesting information listed above is just that, meaning we can't change anything except our own driving habitats.
Coming from a history of performance ICE vehicles with lot of gauges, I monitor my battery usage probably more than some, meaning the % left on the battery and the average energy Wh/mi used for a given trip or distance. These help keep me to maintain a good (rate of usage) or attaining my target end %, I do a couple of easy tasks. (1) I set the cars GPS to my next destination (usually the next supercharger) and note the ending battery % left for the next destination. I try to charge up to where it is at least 30% or more...sometimes that last little bit can take for ever. We've all been there...2% more or sit for 15 min. Now that % reading is the cars projected amount of battery life left if all goes according to plan...So as I start out I continue to watch that ending percentage, it will begin to to fluctuate, meaning lose or gain a percent or two. So to maintain my target ending %, I adjust my cruising speed and I kick the heater on and off if needed. This may seen very elementary to some, but I have even been able to gain on the ending % most of the time. This practice is take some experimenting and can in general, help you get a feel for how the car reacts to changing driving conditions.

 

[Nocturnal]

- Glass roof is not helping either. When I touched the roof from inside it was extremely cold despite keeping the cabin around 68 degrees, all the cabin heat rising up met this freezing piece of glass making the heater work harder just to keep up with the heat loss.

- Wipers are useless without a heating element that a 20k Corolla has. After the first time I had to spray, most of the wiper surface end up freezing and making them smudge the windshield instead of cleaning it.

- I constantly had to direct heat to the windshield to avoid it from fogging and freezing, a heated windshield would have cut down my heater use significantly

I didn't even realize that cars had that as an option now. I've had the same experience in wet, but cold weather.

Regarding the glass roof, it doesn't help us, but the new Tesla patent for an insulated glass roof will help future vehicles.

 

[Redbird]

SR+ 90 mile trip. Temps below freezing

First road trip - ok, mini road trip. I was expecting some range loss but was surprised by almost 50%. 77 of the 90 miles was on the highway so not sure of the impact of cruising at 77.

Way out - day: 27 degrees, sun shining
Charged to 230 miles, little over 90%. Got there with 93 miles left, about 37%. Used about 140 of range to go 90 miles.

Way back - night: 22 deg car cooooold
Level 2 charged to 188. Energy graph said I would get home with 11%, actual was 14%, so did not need to spare the heat, radio or speed.

The trip worked as the level two was close and I had 3+ hours before my return. Also had a super charger 20 min away. If I wanted to leave after an hour, not sure I could make that work in the winter time With just the level 2. Will do the trip again in spring and summer, will be interesting to see the differences

Car drove great, fun ride!

but heating is a range killer. More than I expected. I think we might need better solutions or bigger batteries. Can’t wait for battery day.

 

[Redbird]

Generally I find that down to 0 C is fairly good but we had a bit of minus 36-38 in January and that ate a lot of range. At those temperatures the seat warmer is insufficient. Maybe Tesla should include a stadium blanket in its lineup of swag1

 

[colojohn]

I'll chime in on this, I ran some tests while sitting in traffic near the Eisenhower tunnel. (Ok, that's a lie, I was completely stopped, traffic is an understatement).
Anyway, the only thing that jumped out for discernible power use was the rear window heater, it draws about 300w if I remember correctly. The seat heater was hard to measure, but maybe half that on high.
I didn't test the max heat option, but I can test that later. I did have manual air controls on, I think it was like 20ºF outside, 69º inside, fan speed 3 or 4, with floor, windshield and vent on, no AC. It was also hard to see that show up.
Obviously couldn't measure any battery heating, but my take away from this and warmer drives at high speed is that speed is the big eater here. Max defrost also uses tons of power, but at 80mph at 40-45º ish, it seemed like I was getting less than 200miles on my LRAWD3.

 

[JLuszczek]

An ethanol heater that is properly integrated into the system, by which I mean it injects heated air right into the vents and it exhausts to the outside would be a perfectly sensible solution. All the kWh's that go toward resistive heating are mostly not CO2-free and they are better utilized when they propel the car. Some real engineering firm could build an aftermarket unit that drops in the frunk and connects to existing ducts.
I would definitely not attempt to use a propane space heater inside the cabin, but I would spend a Grand on an aftermarket system that saves me 40% of range in winter.

 

[dcdttu]

A diesel fueled heater for the cabin and battery similar to the ones used in planes and boats would be great with a small fuel tank. Lots of heat and less CO2 emissions than using the battery in almost all cases.

Considering the simple act of refining crude oil into gas uses more electricity than many EVs use to actually drive, this is woefully incorrect.

 

[DR61]

An ethanol heater that is properly integrated into the system, by which I mean it injects heated air right into the vents and it exhausts to the outside would be a perfectly sensible solution.

Interestingly, Volvo did this with their C30 EV back in 2011. I don't know about their newer models.
Volvo C30 Electric equipped with three climate systems; bioethanol heater

 

[Stratusbill]

Huuuuuggggeeeeee impact at "cruising at 77". Its not linear power usage its more like exponential. "cruising at 60" is much much much much (much much much much) more efficient, from a power usage, not counting heat. It will take you longer to get there going 60 than 77 so not sure how that math works out, but people really discount the effect speed has on range, and it is HUUUUUGGGGGGGEEEEEEEEEEEEEEEEEEE

Drag is proportional to the square of velocity. 77 is 28% greater than 60, so it requires 64.7% more energy. I would say just HUUGGEE.

 

[milleron]

I agree that heat pumps are not a solution to more range in extreme cold.

However, the vast majority of people do not deal with regular extreme cold.
People are much more likely to deal with a lot of cold, and occasional extreme cold, or a lot of what-I-used-to-call-cold, and some cold.

The normal patterns in temperate to cold climates is where a heat pump would help, because it'd raise the typical efficiency and range, lowering operating cost and increasing utility.

However, the question is, how much would the heat pump cost? Because the money could be spent on extra battery capacity. Extra battery capacity increases range when you don't need heat, and increases your fast charging rate.

To me, there is no single solution.
Resistive and capacity for hotter climates.
Heat pump for mild and cold climates.
Fuel heater for extremely cold climates (and I don't include my Central Maine climate in that, a heat pump would be a better balance). Longer term I would favor ethanol heating over diesel, since it's cleaner (with good heaters), we produce a ton of it and will always produce it, and we could do with saving the diesel for the hardest uses to replace.

In fact, no heat is really necessary for mild-to-moderately cold climates. I don't live in Canada where they get subzero (Fº) temps, but I live in the Rust Belt where winters can be severe. I've had my Model S through 3 winters, now, and I've yet to even turn on the heat at all other than when I'm forced to run the defroster, which, even then, I use only intermittently. I do sometimes use the steering-wheel heat and, rarely, the seat heater, but I've been very comfortable driving in temps below 20º -- I just wear a few layers, and it's not even chilly, emphasis on not even. In the age of global warming and BEVs, I do not consider this even a minor inconvenience. It's absolutely trivial. Let's all man up and turn off the damned heat in the winter. Doing that in central Ohio, charging prior to departing, heating the cabin just prior to departure on shore power, and driving at the speed limit leave me with a winter-time average of 247 wh/mile which TeslaFi considers to be about 110% efficient. (I'd estimate that about ⅓ of this winter driving is on the freeway at 60-65 mph, the rest, at an average speed of 35-40 mph.)

 

[ellett]

1. Before you leave, while still plugged in, heat the cabin for a half hour or so, so the heat permeates the seats, dash and the rest of the cabin. That way, when you leave, your heater won't be fighting an uphill battle to heat a cold interior. Run the heat up to something like 85° Fahrenheit /30° Celsius.
2. Plan your charging so it finishes right before you leave, to make sure the battery is warm. That doesn't do anything for your comfort, but it maximizes battery efficiency/range.
3. Use the heater, but keep the temperature low, maybe 50° Fahrenheit / 10° Celsius, whatever is comfortable with a heavy sweater
4. Use the seat heaters, which are much more efficient than the vabinheater.
5. If you SuperCharge mid-trip, heat the car interior back up to 85° Fahrenheit /30° Celsius while charging.

And, yes, too bad the M3 doesn't have a heated steering wheel. Elon says a heated wheel isn't good with "vegetarian leather".

Scheduling charging is a function of the Tesla, and scheduling preheating the cabin can be automated using something like TeslaTasks, so you don't have to keep track of everything manually as you're prepping for your trip.

 

[Manitoba Keith]

Speed Kills - Battery. Look at the graphs here Tesla Range Table - Teslike.com Pick you car and battery
The difference between 55 and 75 is OVER 100 miles of range on my LR DM !
Want more range - SLOW DOWN. It really is that simple. Sure, very cold weather will suck 35-40% of the batteries range, but no where near as much as driving 75 instead of 65 or 55 will. When I am in very cold and need more range, I slow to 55 and have at times slowed to 40 (arrived with 2 miles left!). As for heat, look at the Energy Graph while driving and see what the heater uses.

 

[insaneoctane]

Huuuuuggggeeeeee impact at "cruising at 77". Its not linear power usage its more like exponential. "cruising at 60" is much much much much (much much much much) more efficient, from a power usage, not counting heat. It will take you longer to get there going 60 than 77 so not sure how that math works out, but people really discount the effect speed has on range, and it is HUUUUUGGGGGGGEEEEEEEEEEEEEEEEEEE

Just started reading the thread, so sorry if someone downstream already said this.....but, yes, 77 MPH is a factor. Some time last year, I calculated the maximum range as 20MPH. Here's the fraction of that you get as you go faster.....

MPH    % of max range
20    100%
30    94%
35    88%
40    81%
45    75%
50    68%
55    62%
60    57%
65    52%
70    47%
75    43%
80    39%
85    36%
90    33%

 

[bwestlak]

Yup. Found out the hard way. Did a ~266 mile trip (each way). I was getting closer to 200 on a charge than the rated 299 when cruising around 77.

The other thing to keep in mind is the energy use for heating is not linear either. You cannot use the energy usage for the first 20 miles to extrapolate the last 20 miles the heating energy needed is not the same. Getting the KWh per mile to settle down by limiting speed and keeping the heat constant will give you a better picture of your actual range. Over a full charge I have never experienced a 50% loss of range in any Tesla.

 

[WdstockWizard]

...and the heat pump would be powered with....? I’m thinking the battery that makes you go!

 

[WdstockWizard]

I

A diesel fueled heater for the cabin and battery similar to the ones used in planes and boats would be great with a small fuel tank. Lots of heat and less CO2 emissions than using the battery in almost all cases.

I just know you’re kidding. Isn’t the idea of an EV to get away from fossil fuel? Duh!

 

[JIson16]

Cold range loss was my biggest surprise. At 0C (32F), I am losing about 35%. At -20C (-4F) about 45%. Planning highway trips gets important. M3LR Dual Motor.