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Strong headwinds and high speed actual range

gilscales

Active Member
Jul 16, 2016
1,684
1,905
Long Beach, CA
I was heading back from Henderson, NV to Long Beach, CA yesterday and thought I would share the trip with you to give new road trippers an insight to the model 3 with 19" sport wheels (40 psi on tires) in adverse conditions (some mine and some mother nature)

I left with 297 miles rated range and plugged my home address in at 265 miles away, the nav unit did not calculate any stops but I knew that I would most likely need to stop as Traffic flow was at least 80 mph

When I left we were traveling almost head on into 30 to 40 mph winds (those winds were present about 90% of the trip) and I set auto pilot to flow with the traffic so we were really moving, rated range was disappearing much faster than actual miles driven which I did expect and after quite a while the nav re routed me to the Yermo supercharger, I decided that we would rather stop at the Rancho Cucamonga supercharger so we could have a bite to eat at a decent restaurant at about the right time for dinner, nav unit said we should have plenty of range so I kept traveling at high speed into strong headwinds.

About 6 miles before we got to the top of Cajon pass we had 38 miles rated and 30 miles to the supercharger, I knew we were cutting it close but the downhill run would save us, then we hit 5 to 15 mph traffic all the way to the top of the pass and I started to worry a little as we were consuming 400 Wh/mi or more in this uphill traffic, we hit the top of the pass with 29 range and 24 to go actual, with auto pilot still on we coasted downhill almost the entire rest of the way still in heavy traffic and arrived with 26 rated miles left so 3 miles rated range burned traveling the last 24 miles.

All together we traveled 217 actual miles on 271 rated miles of range in 100 degree temps, strong headwinds and very high speeds the whole way on 19" sport wheels with 40 psi in the tires (cold) so with all that we still managed over 80% of rated range and I was very happy with that.

When we stopped at the Rancho supercharger I charged for only 15 minutes and got back 106 miles rated range! I cannot imagine how the V3 Supercharger is going to be!
io47tCJ5TeG1uuV9hN6lyQ.jpg
 

idoco

Member
May 7, 2013
555
609
Outside Philly
We had the same situation crossing Kansas last month. If it's windy and range is an issue I like using TeslaWinds in the browser.

In the picture below we are going at 74mph but using energy equivalent to going 100mph! If I know that I could normally have to go 74 mph without weather to make the trip I'll adjust my speed so that the airspeed would be 74 mph. Of course this means the ground speed will be about 50 mph:-(

winddisplay3.jpeg
 

EkBuZ

Member
Mar 9, 2016
72
36
North Dakota, USA
You gotta love downhills and drafting in heavy traffic. For another data point, I was going into a 30+ mph sustained headwind in North Dakota. The road was mostly flat, with a slight uphill, and nobody around to break the wind. With Aero wheels, while going 78 mph I was using ~400 Watt/mi. That would equate to max range of 190 miles.
 

SageBrush

REJECT Fascism
May 7, 2015
12,404
15,347
New Mexico
When I left we were traveling almost head on into 30 to 40 mph winds (those winds were present about 90% of the trip)
Nah *

But impressive story regardless

*
118 mph (80 mph + 38 mph headwind) is ~ 56 kW just to overcome Aero drag and rolling friction. Range would be < 120 miles
 

gilscales

Active Member
Jul 16, 2016
1,684
1,905
Long Beach, CA
Nah *

But impressive story regardless

*
118 mph (80 mph + 38 mph headwind) is ~ 56 kW just to overcome Aero drag and rolling friction. Range would be < 120 miles

Ok, I admit the headwinds were a guess but i did see at least 4 or 5 flags flying on the way home and they were all standing straight out and almost right at our direction of travel, we did hit some traffic now and then but mostly 80 mph as that is where i set my max speed, for a while i was getting over to let people pass as i just didn't feel like i would make it to my supercharger choice traveling any faster plus theres the speeding ticket thing.
 

gilscales

Active Member
Jul 16, 2016
1,684
1,905
Long Beach, CA
I looked at historic weather data to see if I was exaggerating and in Henderson, NV at 1:55 p.m. on 5/30/18 near the time I left wind speed was 28.8 mph with 36.8 mph gusts, SSE direction, I really did try to remember everything and accurately report my findings for what I thought would be good useful info, Someone suggested I plug this trip into EVTO and it had me coming up short by 5 miles instead of arriving with 26, all I can say is maybe my average speed was low enough at the end to change things quite a bit as there was traffic 6 miles before the Cajon summit and most of the remaining 24 miles down hill on the other side averaging 5 to 15 mph, plug that into your calculator @SageBrush and see what you come up with?
 

Candleflame

Active Member
Mar 9, 2015
2,960
1,380
QLD, Australia
What the heck, there’s an app for wind speed for your Tesla?? Need

makes a big difference on gas cars too. I remember one day I drove from Germany to the UK and managed to squeeze 1200km range out of my 63L diesel tank which included driving at over 240kmh on the autobahn. on the back journey i only got like 900km out of one tank.
 

daniel

Active Member
May 7, 2009
4,906
3,719
Kihei, HI
I was heading back from Henderson, NV to Long Beach, CA yesterday <...snip...> so with all that we still managed over 80% of rated range and I was very happy with that.

Were you using air conditioning in that 100° heat?

Your report is great news for me, because I have a road trip this summer with a 243-mile leg. But I'm not anticipating high winds, and I can drive 55 mph. It could be warm, though, and I'd like to use A/C if it is. I've heard/read that it's more efficient to use A/C than to open windows. And even at 55 mph open windows are not comfortable.
 

SageBrush

REJECT Fascism
May 7, 2015
12,404
15,347
New Mexico
plug that into your calculator @SageBrush and see what you come up with?
No calculator here, just the physics of aero drag and rolling friction and some barely remembered HS trig.
Wind is *really* tricky. It can change direction and speed a lot in an hour or two, your car does the same or more, and figuring out wind vectors takes some work *. Don't take offense at my comment -- I don't doubt the impressive fuel economy of the car. I only wished to point out that a 38 mph headwind on top of 80 mph driving cannot be sustained for long with a 75 kWh battery.

*
By the way, SSE is about 158 degrees and by eyeballing it looks like your general direction home was 225 degrees for a difference of 67 degrees between wind direction and your travel direction. Or did you mean that the wind came from the SSE ? In the first case the wind would actually have helped; in the second case of 113 degrees, the wind vector is wind_speed * sinus (23 degrees) = wind_speed * 0.4. If this arithmetic is correct then the corrected headwind is 28*0.4 = 11 mph, your aero speed is 91 mph and the aero drag is 535 Newtons, or 21.5 kW at an odometer speed of 80 mph. That sounds ballpark to me.

I think. I was too lazy to draw this out so my figuring with thumbs and fingers may have errors.
 
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Electroman

Supporting Member
Aug 18, 2012
6,260
6,414
TX
Were you using air conditioning in that 100° heat?

Yesterday I drove back home at 103F with AC comfortably set to 74F and the speeds ranging from 70mph on small sections but mostly heavy traffic that was lumbering between 25 to 55. The 40 mile stretch took around an hour

And my efficiency was a whopping... <drum roll> 222 wh/mile for that trip, which is actually better than the EPA. I consumed 2 miles less than I traveled. For the most part the efficiency was around 210 and it increased to 222 only during the last few miles of stop and go traffic on lights. AC had very little impact on the efficiency. I think the thinner air compensates quite nicely for the AC at higher temps
 
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gilscales

Active Member
Jul 16, 2016
1,684
1,905
Long Beach, CA
Were you using air conditioning in that 100° heat?

Your report is great news for me, because I have a road trip this summer with a 243-mile leg. But I'm not anticipating high winds, and I can drive 55 mph. It could be warm, though, and I'd like to use A/C if it is. I've heard/read that it's more efficient to use A/C than to open windows. And even at 55 mph open windows are not comfortable.

Yes the a/c was on the entire trip
 
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gilscales

Active Member
Jul 16, 2016
1,684
1,905
Long Beach, CA
No calculator here, just the physics of aero drag and rolling friction and some barely remembered HS trig.
Wind is *really* tricky. It can change direction and speed a lot in an hour or two, your car does the same or more, and figuring out wind vectors takes some work *. Don't take offense at my comment -- I don't doubt the impressive fuel economy of the car. I only wished to point out that a 38 mph headwind on top of 80 mph driving cannot be sustained for long with a 75 kWh battery.

*
By the way, SSE is about 158 degrees and by eyeballing it looks like your general direction home was 225 degrees for a difference of 67 degrees between wind direction and your travel direction. Or did you mean that the wind came from the SSE ? In the first case the wind would actually have helped; in the second case of 113 degrees, the wind vector is wind_speed * sinus (23 degrees) = wind_speed * 0.4. If this arithmetic is correct then the corrected headwind is 28*0.4 = 11 mph, your aero speed is 91 mph and the aero drag is 535 Newtons, or 21.5 kW at an odometer speed of 80 mph. That sounds ballpark to me.

I think. I was too lazy to draw this out so my figuring with thumbs and fingers may have errors.


Looking at my quote from you it does sound like I was offended, that was not the case and I did not mean to come off like that, when I looked up the weather it just said SSE so I assume that meant the direction of travel of the wind?

I just remembered passing a few flags flying hard and looking from my viewpoint it seemed mostly head on but I'm sure that varied a lot, I did feel the car being pushed around by the wind so I don't expect that it was always head on, I was just really impressed by the trip under such adverse conditions and wanted to share that while the details were fresh in my mind but my details are probably less detailed and more guesswork
 
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daniel

Active Member
May 7, 2009
4,906
3,719
Kihei, HI
Yes the a/c was on the entire trip

Thanks for that. I'm feeling much more confident about my trip. My past experience with both the Zap Xebra and the Roadster never included A/C. The Xebra didn't have it, but did have a heater; and in the Roadster I never used A/C because I just put the mesh top on in hot weather and enjoyed the natural air. (I really love the mesh top in warm weather!) Both cars showed real reduction in range when the heater was used, and I had no idea how much energy A/C consumes.
 

SageBrush

REJECT Fascism
May 7, 2015
12,404
15,347
New Mexico
I looked up the weather it just said SSE so I assume that meant the direction of travel of the wind?
I'm not sure if a convention is followed by all the weather services. I use Wunderground, which reports the direction the wind is coming from. If e.g. the wind direction is reported South then the wind will be in your face when you face South.
 

bmah

Moderator
Mar 17, 2015
4,056
7,420
Lafayette, CA, USA
I'm not sure if a convention is followed by all the weather services. I use Wunderground, which reports the direction the wind is coming from. If e.g. the wind direction is reported South then the wind will be in your face when you face South.

I thought that was a pretty accepted convention...I've never heard wind direction reported any other way.

When we had the TMC meet-up at the Kettleman City Supercharger back in February, it was on a unusually windy day, and IIRC pretty much everyone from the Bay Area (or points north) had to make an extra charging stop on the way home.

Bruce.
 

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