Windy road trip 40MPH Headwinds

[On the Road with Ralph]

For the next several trips to Glendora, we charged to >85% at Needles.

I used to hate stopping at the EA site in Needles because it was usually throttled/derated, that in turn led to a wait line. As soon as I could, I switched to the Tesla stations (usually the one on the south side of town) - never a line, MUCH cheaper than EA, and I could grab either lunch or dinner at the Indian restaurant next door.

Barstow is one of those places where EA is a bad joke (Quartzsite is another). Tesla has 230 charging stalls in the Barstow area; EA has eight (and they rarely all work).

Wishlist: A DCFC station in Seligman.

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[SpaceEVDriver]

I used to hate stopping at the EA site in Needles because it was usually throttled/derated, that in turn led to a wait line. As soon as I could, I switched to the Tesla stations (usually the one on the south side of town) - never a line, MUCH cheaper than EA, and I could grab either lunch or dinner at the Indian restaurant next door.

Barstow is one of those places where EA is a bad joke (Quartzsite is another). Tesla has 230 charging stalls in the Barstow area; EA has eight (and they rarely all work).

Wishlist: A DCFC station in Seligman.

I detest the brand T stations in Needles. The one on the East side is in a dead strip mall with just a gas station with a gross restroom nearby. The other is okay, but the lot is very tight and I can't use it when I'm towing.

The Rivian chargers in Barstow are my go-to, despite their price premium. They're reliable, much, much faster than the brand-T and seem to be unused most of the time.

 

[On the Road with Ralph]

The Rivian chargers in Barstow are my go-to, despite their price premium. They're reliable, much, much faster than the brand-T and seem to be unused most of the time.

I can appreciate why you like the Rivian station - it has a pull-through. FYI, tho - the 120 stall Tesla station on Main Street has pull-thrus plus it is so huge that there are usually gaps large enough to park parallel to the curb. Also, it has the faster V4 dispensers.

I think it is interesting that your experience has found the Tesla chargers are slow. For the most part, I don’t notice any meaningful difference between them and a fully functioning EA Hypercharger. Maybe a slightly lower initial peak - I’ve seen 181 on EA Gen4 units, and only 168 or so on a Tesla. But after the first ten minutes, it is all the same on my SR Pro.

 

[SpaceEVDriver]

I can appreciate why you like the Rivian station - it has a pull-through. FYI, tho - the 120 stall Tesla station on Main Street has pull-thrus plus it is so huge that there are usually gaps large enough to park parallel to the curb. Also, it has the faster V4 dispensers.

I think it is interesting that your experience has found the Tesla chargers are slow. For the most part, I don’t notice any meaningful difference between them and a fully functioning EA Hypercharger. Maybe a slightly lower initial peak - I’ve seen 181 on EA Gen4 units, and only 168 or so on a Tesla. But after the first ten minutes, it is all the same on my SR Pro.

Yeah. I've used the superchargers in Barstow, but...

• They're slower (usually average about 100-120 kW on my ER vs 140 kW at the RAN vs 140 kW at the EA)
• They're farther from food
• I'm not a fan of the company that owns those chargers

 

[WaterboyNorCal]

I bought by 2024 Flash back in November of 2024, but today was the first time I took it on a longer road trip. I was heading from just west of Kansas City to Rogers, AR a distance of only 236 miles. My original plan was to stop in Joplin, MO and hit a Supercharger to top off the battery before making the final hour or so down to Rogers.

I charged my truck at home to full 100% capacity this morning. They already had the red flag warnings up for extreme winds from the south and they were gusting to 45-50MPH at times. So much for battery efficiency on this trip. I set the cruise at 72MPH and just battled the wind. I could tell that I wasn’t going to make Joplin, MO over 20% so I decided to hit the Tesla SuperCharger at Nevada, MO. First segment of the trip, 1.4mi/KWh. Took the battery from 54% to 80% adding 37 KWh and got back on the road.

Went ahead and hit the planned SuperCharger stop in Joplin, MO. This segment the winds were absolutely fierce and gusty. 1.2mi/KWh. Took the battery from 41% to 80% adding 55 KWh and made the final trek. Pulled into the SuperCharger about 3 miles from my destination to top things off. 1.4mi/KWh on that segment. 48% back up to 80% Adding 46 KWh.

No issues at any location getting charged, was even taking on energy at 180+ KWh for a few minutes at the stop in Nevada, MO. I honestly can‘t think of another time that I bucked a headwind that strong for that long. In my old Coyote V8 F-150 that would have been about a 10-12 MPG trip if I was lucky and would have burned a lot of dinosaur juice.

I hope the wind isn’t busting out of the north on the trip home, but I know where the chargers are now!

Just curious- was there a reason that you had to start your DCFC sessions at such high SOCs? You would have had more efficient stops by charging ~20% to ~50% rather than 50-80% due to much higher charge rates at the lower SOC. I get that sometimes we are hamstrung by DCFC placements; was that the case here?
Also, as others have pointed out, speed is your enemy and especially in the cold and/or against a headwind. Slowing to 65mph would help a lot with efficiency, and could even result in a shorter trip if it helped with DCFC strategy by allowing some longer runs…

 

[VTbuckeye]

Just curious- was there a reason that you had to start your DCFC sessions at such high SOCs? You would have had more efficient stops by charging ~20% to ~50% rather than 50-80% due to much higher charge rates at the lower SOC. I get that sometimes we are hamstrung by DCFC placements; was that the case here?
Also, as others have pointed out, speed is your enemy and especially in the cold and/or against a headwind. Slowing to 65mph would help a lot with efficiency, and could even result in a shorter trip if it helped with DCFC strategy by allowing some longer runs…

I know that it has been a while, but state of charge Tom had an old charging video of the lightning starting at various states of charge going up to 80. There is a hard limit at 80 percent that drips charging down to under 60kW. If the battery is in the correct temperature range, no matter the initial SOC the lightning will charge for 5 to 10 minutes at boosted amperage (450??). Amp X Volts = charge rate, so in theory if you need 30 percent then the fastest 30 percent increase should be from 50 to 80 (maximum Amp rate times the highest Voltage). I don't dcfc enough to have a lot of experience with various charging strategies (usually it is from 20ish to 80ish and I'm not concerned with getting too much charge).

 

[inchman254]

Yeah.

For a direct headwind, energy cost to go a distance is proportional to (vehicle speed + wind speed)^3. For a head-on crosswind, you also have the vehicle's side surface area replacing the front surface area and the coefficient of drag grows to be larger than 1.0 in the drag term of the energy equation.

Don't want to nit-pick but It's squared, not cubed.

And part of the drag cost includes rolling resistance which is close to a constant per [distance]. Mileage would be about 1 mi/kWh higher without rolling resistance. And there are some other losses not related to wind. So the proportional growth in drag due to wind resistance only applies to about 50% of the overall drag/losses at normal speeds. It's easier to pull out the rolling part if units are in kWh/[distance] but few of those here (other than Canadians) use that format.

I did learn something from your reference to crosswinds, though. I thought this was impossible but, after some research, it turns out that up to a 45 degree head/crosswind, the total effect of the headwind plus the turning correction required to keep the car on the road can be up to 10% higher than if the wind was a direct headwind. Beyond 45 degrees, the total effect is below 1x, but the negative overall effect is still about 40% of the wind value at 90 degrees when you would instinctively think it had zero effect. It turns out that a tailwind/crosswind is not even slightly beneficial till the wind is 30 degrees past abeam.

I just did a 3000 mile road trip and couldn't figure out why my consumption was higher than I expected on the days with a crosswind.... now I know. Thanks!

 

[SpaceEVDriver]

Don't want to nit-pick but It's squared, not cubed.

Nope.

E = 1/2 mv^2 is for no external resistances (other than mass/inertia). You have to accelerate the air molecules out of the way, and they must be accelerated up to the velocity of the vehicle. When you integrate over the distance traveled, the final equation has a v^3. I can lay it all out if desired, but it’s a long discussion.

And part of the drag cost includes rolling resistance which is close to a constant per [distance]. Mileage would be about 1 mi/kWh higher without rolling resistance. And there are some other losses not related to wind. So the proportional growth in drag due to wind resistance only applies to about 50% of the overall drag/losses at normal speeds. It's easier to pull out the rolling part if units are in kWh/[distance] but few of those here (other than Canadians) use that format.

This is true, but the energy required to move the vehicle once air resistance matters is still proportional to v^3. You just have a multiplier in front and a non-velocity-related additive term. This is why I used “proportional” in my statement.

 

[WaterboyNorCal]

I know that it has been a while, but state of charge Tom had an old charging video of the lightning starting at various states of charge going up to 80. There is a hard limit at 80 percent that drips charging down to under 60kW. If the battery is in the correct temperature range, no matter the initial SOC the lightning will charge for 5 to 10 minutes at boosted amperage (450??). Amp X Volts = charge rate, so in theory if you need 30 percent then the fastest 30 percent increase should be from 50 to 80 (maximum Amp rate times the highest Voltage). I don't dcfc enough to have a lot of experience with various charging strategies (usually it is from 20ish to 80ish and I'm not concerned with getting too much charge).

I don’t believe this is correct. At least not in my experience. Yes, there is an initial boost when using a DCFC, but it is NOT SOC-agnostic. In my experience, if you are above ~50% SOC, you will not see maximum charging speeds. I have seen the most consistent high charging “boost” between 10% and 40% SOC.

 

[davehu]

....
Went ahead and hit the planned SuperCharger stop in Joplin, MO. This segment the winds were absolutely fierce and gusty. 1.2mi/KWh. Took the battery from 41% to 80% adding 55 KWh and made the final trek. Pulled into the SuperCharger about 3 miles from my destination to top things off. 1.4mi/KWh on that segment. 48% back up to 80% Adding 46 KWh.
...
[/QUOTE]
1.2m/kwh! just think of the great story you could tell if you were heading east that day!

 

[inchman254]

Nope.

E = 1/2 mv^2 is for no external resistances (other than mass/inertia). You have to accelerate the air molecules out of the way, and they must be accelerated up to the velocity of the vehicle. When you integrate over the distance traveled, the final equation has a v^3. I can lay it all out if desired, but it’s a long discussion.

This is true, but the energy required to move the vehicle is still proportional to v^3. You just have a multiplier in front and a non-velocity-related additive term. This is why I used “proportional” in my statement.

I'll try to ignore the condescending Nope.

You might find a speed range comparison where the v^3 thing might work or come close to a real life answer, but it would probably be hiding rolling resistance and other energy losses in that last v. If it works for you as a rule of thumb, then have at it. It would err on the side of safety so that's good, but it's not mathematically supportable and not worth a Nope.

For those who just like to get in their truck and drive.... move on... nothing to see here.

I'm happy to lay it out. I'll try to keep it from being too long. There is no need to integrate mathematically. We are talking about steady state.

To put it in directly intuitive context, think about a vehicle travelling at 30 mph (airspeed) compared to one travelling at 60 mph. Let's look at the proportionality if it was cubed... 60^3/30^3.... 24 times more drag. Even comparing 80 from 60... 2.4 times the drag with cubes. We see numbers going from 2.4 mi/kWh to 1.8 mi/kWh... not to 1.0 mi/kWh with that speed change.

Even the squared calculation doesn't work unless you first remove the rolling drag, then add it back in. The OP, with a 40 mph headwind at 72, would see 6x as much drag using cubed due to the headwind, reducing his mileage to 0.4 (probably closer to 0.7 if rolling resistance were taken into consideration.., but you get the point and it's clear that cubed is not the answer). (And, while the winds were Gusting to 40 or 50, the average would have been lower.)

Not all of the air molecules need to be accelerated up to the speed of the vehicle. They only need to change velocity (speed and/or direction) to incur a force from the truck. A very few will accelerate close to the speed of the vehicle if they have no where to go, others will move out of the way, others will accelerate somewhat but not match the speed of the vehicle. But they all must have a force applied to change speed or direction and that force starts with the truck.

Drag is not energy, it is a FORCE. Energy in our context is force * distance. Yes, kinetic energy = 1/2 mv^2, but that's not what we're talking about here. Kinetic energy applies to regen, not proportional energy use in steady state due to drag.

According to this NASA link , the equation for drag due to wind resistance is:

D = Cd * A * .5 * r * V^2. There is no cube.

Since the coefficient of drag (Cd), the surface area (A) and air density (r)ho, are the same when comparing two speeds in the same medium, the change of drag with speed is proportional to Vee SQUARED.

The easiest way to demonstrate this is using metric. A kilo is 2 pounds and a meter is 1 yard.

For units, Cd is dimensionless, A is m^2, r is kg/m^3, and V is m/sec.

This results in m^2 * kg /m^3 * m^2/sec^2 .
Combining like units results in m^4*kg/m^3*sec^2.
Simplifying, this it becomes kg*m/sec^2 or Newtons... a force. The imperial equivalent of Newtons is poundal (kinda like pound-force).

ENERGY = force * distance. It would be hard to disagree with the fact that a specific drag force applied over 100 miles would use twice as much ENERGY as that same force over 50 miles.

So, for ENERGY, we multiply the drag force by distance, m. The units are now m* (kg*m/sec^2) or kg*m^2/sec^2 or Newton-meters or Joules. (Notice that these energy units are the same as the energy units for the 1/2mv^2 form of energy).

A Joule is a watt-second. We might recognize this unitization as similar to kWh... a unit of ENERGY (but really small in comparison... 3,600,000 J per kWh).

To do this in imperial, the units would be lb-ft^2/sec^2 which can be converted to Joules or Watt-seconds or kWh.

There is no m^3 or miles^3 anywhere in the above except for a brief moment during unit simplification and, even then, it is in the denominator.

I am open to rebuttal.

 

[BSull]

Just completed a 5281 mile cross country loop, I will post a more detailed trip report in a separate posting. Average for the entire trip was 2.0. On interstate the highest I saw was 2.4 @ 75 (tailwinds do exist), the lowest 1.4 @ 75(headwinds do also). I used Tesla, EA, Shell Recharge, EVGO and one level 2 at a hotel.

 

[EVO]

I bought by 2024 Flash back in November of 2024, but today was the first time I took it on a longer road trip. I was heading from just west of Kansas City to Rogers, AR a distance of only 236 miles. My original plan was to stop in Joplin, MO and hit a Supercharger to top off the battery before making the final hour or so down to Rogers.

I charged my truck at home to full 100% capacity this morning. They already had the red flag warnings up for extreme winds from the south and they were gusting to 45-50MPH at times. So much for battery efficiency on this trip. I set the cruise at 72MPH and just battled the wind. I could tell that I wasn’t going to make Joplin, MO over 20% so I decided to hit the Tesla SuperCharger at Nevada, MO. First segment of the trip, 1.4mi/KWh. Took the battery from 54% to 80% adding 37 KWh and got back on the road.

Went ahead and hit the planned SuperCharger stop in Joplin, MO. This segment the winds were absolutely fierce and gusty. 1.2mi/KWh. Took the battery from 41% to 80% adding 55 KWh and made the final trek. Pulled into the SuperCharger about 3 miles from my destination to top things off. 1.4mi/KWh on that segment. 48% back up to 80% Adding 46 KWh.

No issues at any location getting charged, was even taking on energy at 180+ KWh for a few minutes at the stop in Nevada, MO. I honestly can‘t think of another time that I bucked a headwind that strong for that long. In my old Coyote V8 F-150 that would have been about a 10-12 MPG trip if I was lucky and would have burned a lot of dinosaur juice.

I hope the wind isn’t busting out of the north on the trip home, but I know where the chargers are now!

 

[SpaceEVDriver]

I'll try to ignore the condescending Nope.

You might find a speed range comparison where the v^3 thing might work or come close to a real life answer, but it would probably be hiding rolling resistance and other energy losses in that last v. If it works for you as a rule of thumb, then have at it. It would err on the side of safety so that's good, but it's not mathematically supportable and not worth a Nope.

For those who just like to get in their truck and drive.... move on... nothing to see here.

I'm happy to lay it out. I'll try to keep it from being too long. There is no need to integrate mathematically. We are talking about steady state.

To put it in directly intuitive context, think about a vehicle travelling at 30 mph (airspeed) compared to one travelling at 60 mph. Let's look at the proportionality if it was cubed... 60^3/30^3.... 24 times more drag. Even comparing 80 from 60... 2.4 times the drag with cubes. We see numbers going from 2.4 mi/kWh to 1.8 mi/kWh... not to 1.0 mi/kWh with that speed change.

Even the squared calculation doesn't work unless you first remove the rolling drag, then add it back in. The OP, with a 40 mph headwind at 72, would see 6x as much drag using cubed due to the headwind, reducing his mileage to 0.4 (probably closer to 0.7 if rolling resistance were taken into consideration.., but you get the point and it's clear that cubed is not the answer). (And, while the winds were Gusting to 40 or 50, the average would have been lower.)

Not all of the air molecules need to be accelerated up to the speed of the vehicle. They only need to change velocity (speed and/or direction) to incur a force from the truck. A very few will accelerate close to the speed of the vehicle if they have no where to go, others will move out of the way, others will accelerate somewhat but not match the speed of the vehicle. But they all must have a force applied to change speed or direction and that force starts with the truck.

Drag is not energy, it is a FORCE. Energy in our context is force * distance. Yes, kinetic energy = 1/2 mv^2, but that's not what we're talking about here. Kinetic energy applies to regen, not proportional energy use in steady state due to drag.

According to this NASA link , the equation for drag due to wind resistance is:

D = Cd * A * .5 * r * V^2. There is no cube.

Since the coefficient of drag (Cd), the surface area (A) and air density (r)ho, are the same when comparing two speeds in the same medium, the change of drag with speed is proportional to Vee SQUARED.

The easiest way to demonstrate this is using metric. A kilo is 2 pounds and a meter is 1 yard.

For units, Cd is dimensionless, A is m^2, r is kg/m^3, and V is m/sec.

This results in m^2 * kg /m^3 * m^2/sec^2 .
Combining like units results in m^4*kg/m^3*sec^2.
Simplifying, this it becomes kg*m/sec^2 or Newtons... a force. The imperial equivalent of Newtons is poundal (kinda like pound-force).

ENERGY = force * distance. It would be hard to disagree with the fact that a specific drag force applied over 100 miles would use twice as much ENERGY as that same force over 50 miles.

So, for ENERGY, we multiply the drag force by distance, m. The units are now m* (kg*m/sec^2) or kg*m^2/sec^2 or Newton-meters or Joules. (Notice that these energy units are the same as the energy units for the 1/2mv^2 form of energy).

A Joule is a watt-second. We might recognize this unitization as similar to kWh... a unit of ENERGY (but really small in comparison... 3,600,000 J per kWh).

To do this in imperial, the units would be lb-ft^2/sec^2 which can be converted to Joules or Watt-seconds or kWh.

There is no m^3 or miles^3 anywhere in the above except for a brief moment during unit simplification and, even then, it is in the denominator.

I am open to rebuttal.

The “nope” wasn’t meant to be condescending. My apologies for that.

 

[SD39U]

Just curious- was there a reason that you had to start your DCFC sessions at such high SOCs? You would have had more efficient stops by charging ~20% to ~50% rather than 50-80% due to much higher charge rates at the lower SOC. I get that sometimes we are hamstrung by DCFC placements; was that the case here?
Also, as others have pointed out, speed is your enemy and especially in the cold and/or against a headwind. Slowing to 65mph would help a lot with efficiency, and could even result in a shorter trip if it helped with DCFC strategy by allowing some longer runs…

That was the challenge. Stop in Nevada or stop in Joplin. SW Missouri isn’t very populated with DCFC’s (or population either) so I had to do what I had to do.

I planned it all out ahead of time.

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