"Practical" range on road trips is about 50% of EPA estimate for most EVs

[Golfhack]

This is why the increased range of the Lucid is so key. Let me explain.

I have a Lucid Air Touring with 19" wheels (aerocaps removed). I have just over 15K miles and my lifetime efficiency is 3.6 miles/kWhr. This translates to a range of 331 miles (3.6 x 92kWh battery size) or about 78% of the EPA estimated range of 425 miles. Real world driving means 75-80 mph on the highway, occasional cold temps, occasional launches/spirited driving. Given all these variables I am very happy with my efficiency and range. So why do I say that real world "practical" range on a road trip is 50%, not 78%? Because you never go all the way to 0% and when charging at a DC fast charger, it is inefficient to charge past 80% or so. Personally, I never go below 15% SOC and typically stop fast charging when I reach 80%. Therefore, I use only 65% of my battery capacity. 65% of 78% is 51%. In my car, this translates to 215 miles. For me, this is plenty, but it is far less than the EPA number of 425 miles and highlights the importance of understanding "practical range" for EV owners. It makes me value my Lucid all the more. A friend of mine has a MachE with an EPA rated range of 250 miles. His "practical" range on a road trip is only 125 miles and makes long road trips for him somewhat difficult since he has to stop for 30 minutes every 2 hours. In my Lucid, I stop for 30 minutes every 3.5 hours.

I didn't really understand this when I first bought my Lucid but I think it's important for new (and old) EV owners to know.

 

[xponents]

This is why the increased range of the Lucid is so key. Let me explain.

I have a Lucid Air Touring with 19" wheels (aerocaps removed). I have just over 15K miles and my lifetime efficiency is 3.6 miles/kWhr. This translates to a range of 331 miles (3.6 x 92kWh battery size) or about 78% of the EPA estimated range of 425 miles. Real world driving means 75-80 mph on the highway, occasional cold temps, occasional launches/spirited driving. Given all these variables I am very happy with my efficiency and range. So why do I say that real world "practical" range on a road trip is 50%, not 78%? Because you never go all the way to 0% and when charging at a DC fast charger, it is inefficient to charge past 80% or so. Personally, I never go below 15% SOC and typically stop fast charging when I reach 80%. Therefore, I use only 65% of my battery capacity. 65% of 78% is 51%. In my car, this translates to 215 miles. For me, this is plenty, but it is far less than the EPA number of 425 miles and highlights the importance of understanding "practical range" for EV owners. It makes me value my Lucid all the more. A friend of mine has a MachE with an EPA rated range of 250 miles. His "practical" range on a road trip is only 125 miles and makes long road trips for him somewhat difficult since he has to stop for 30 minutes every 2 hours. In my Lucid, I stop for 30 minutes every 3.5 hours.

I didn't really understand this when I first bought my Lucid but I think it's important for new (and old) EV owners to know.

Agreed. If you can decrease your speed even 2 mph range will greatly increase as drag increases by the cube of mph.

 

[kurious]

I think it's the square of mph not the cube (an aeronautical engineer corrected me once) but the point is solid, go slower to go farther on the same fuel or charge. I've read that most cars' most aerodynamically (and fuel-) efficient speed is ~40-50mph. I wonder how that applies to the Air with super-low coefficient of drag. I assume it's most efficient speed is maybe 48-55mph but just guessing.

 

[xponents]

I think it's the square of mph not the cube (an aeronautical engineer corrected me once) but the point is solid, go slower to go farther on the same fuel or charge. I've read that most cars' most aerodynamically (and fuel-) efficient speed is ~40-50mph. I wonder how that applies to the Air with super-low coefficient of drag. I assume it's most efficient speed is maybe 48-55mph but just guessing.

My bad, others on the forum had said it is the cube(edit: google also does, I think you may be mistaken)

Lucid told some people that about 28 mph is the most efficient speed, but realistically going 55~65 should give you close to if not the same as EPA range. Also keep in mind temperature(outside and inside, battery cooling + hvac respectively) and elevation are major impacts.

 

[kurious]

Here's a good article explaining the velocity-squared term. There are many more.
If you have a credible article showing cubed please share.

Drag Coefficient And Velocity: Relation,Different Aspects And Facts - TechieScience

The drag is a force associated with the object in motion in a fluid environment. Drag force is specified by a dimensionless entity called drag coefficient,

lambdageeks.com

 

[xponents]

Here's a good article explaining the velocity-squared term. There are many more.
If you have a credible article showing cubed please share.

Drag Coefficient And Velocity: Relation,Different Aspects And Facts - TechieScience

The drag is a force associated with the object in motion in a fluid environment. Drag force is specified by a dimensionless entity called drag coefficient,

lambdageeks.com

It looks like it is very complex: I am aware it isn’t exactly “credible,” I will search more

 

[DeaneG]

Fortunately, I "have a degree in science".
Aero drag force increases with the square of speed.
Power to propel an object at a given speed increases with the cube of speed. (~ increased force with speed* increased speed)
Energy to move an object a given distance increases with the square of speed (~ increased power with speed * decreased time)

 

[DeaneG]

...A friend of mine has a MachE with an EPA rated range of 250 miles. His "practical" range on a road trip is only 125 miles and makes long road trips for him somewhat difficult since he has to stop for 30 minutes every 2 hours. In my Lucid, I stop for 30 minutes every 3.5 hours.

Agree completely. Here are our roughly typical trip leg lengths at ~75mph freeway speed in our two very different EVs:

Volvo XC40 EV: 150 miles for first leg, (starting at 100%), 90-100 miles for each additional leg for fastest charging

Lucid Grand Touring: 320 miles first leg (starting at 100%), ~220 miles for each additional leg for fastest charging

 

[xponents]

Fortunately, I "have a degree in science".
Aero drag force increases with the square of speed.
Power to propel an object at a given speed increases with the cube of speed. (~ increased force with speed* increased speed)
Energy to move an object a given distance increases with the square of speed (~ increased power with speed * decreased time)

Glad this could be cleared up, thank you! Maybe an addition to the FAQS?

 

[DeaneG]

The result is that at high enough speeds range decreases roughly with the square of speed. This simplistic square-law answer is modified in practice somewhat by motor efficiency charges with speed, tire losses, etc.

 

[Instinctive]

At the end of the day that's all well and good, but for the average American road tripper (I think I'm much more in this demo than the cutting edge innovator style early adopters this forum tends to be predominantly) I don't really care that the charge lasts longer at a bit lower speed. I'm comparing it to a gas car that I can drive at an average of 75-80 miles for 300+ miles and be very confident I can get it pretty darn low and find a place to stop for 10 minutes and be on my way with snacks, a bio break, and a full tank. So "you can drive slower to get closer to the range" isn't useful advice.

It's a clear drawback of all EVs, not just this one. And the Air does a great job of getting real, longer range, and real, better ability to charge faster. That's why I've considered it...alongside the fact that it is WAY better for local driving with home charging easy peasy.

 

[kurious]

Me too! Fast and carefree are the normal M.O. and joy of this car.
I like to understand the efficiency envelope for the rare situation where I may find myself needing to go farther on whatever charge I have at the time. I think most of us have encountered this with gasoline-powered cars at one point or another, rolling into a gas station "on fumes" in the tank.

 

[Steveinarizona]

Agreed. If you can decrease your speed even 2 mph range will greatly increase as drag increases by the cube of mph.

But that's no fun.

 

[xponents]

But that's no fun.

I am a new jersey resident, and it is alien to me how high the speed limits are in much of the west US. For us, going 65 is already above the speed limit, and would likely net an Air about 4.4-4.6 mi/kwh(about 490-515 miles of range on a 19 GT). Then I read how people go in the 90s and sometimes 100s and I get confused, as that does not exist here.

It is no fun getting gapped by a Toyota Sienna with 6 kids and a rabid BMW driver honking and flashing the highs 1 foot behind your bumper though, I agree.

 

[Knucklehead]

I am a new jersey resident, and it is alien to me how high the speed limits are in much of the west US. For us, going 65 is already above the speed limit, and would likely net an Air about 4.4-4.6 mi/kwh(about 490-515 miles of range on a 19 GT). Then I read how people go in the 90s and sometimes 100s and I get confused, as that does not exist here.

It is no fun getting gapped by a Toyota Sienna with 6 kids and a rabid BMW driver honking and flashing the highs 1 foot behind your bumper though, I agree.

Last time I drove on the NJ Turnpike, people were driving a lot faster than 65.

 

[xponents]

Last time I drove on the NJ Turnpike, people were driving a lot faster than 65.

What part of NJ do you live in?

And various people go different speeds.. just that my family goes at 65 although I beg for 95. What speed do you go at?

 

[Haggy]

This is why the increased range of the Lucid is so key. Let me explain.
. So why do I say that real world "practical" range on a road trip is 50%, not 78%? Because you never go all the way to 0% and when charging at a DC fast charger, it is inefficient to charge past 80% or so.

You could say that with an ICEV, the "practical" range is up to the point where you'd want to get gasoline, which might be 1/4 or 1/8 tank. I'd rather go by real world needs. There's not going to be a charging stop exactly at the point where you drop to a certain state of charge. So I'm likely to charge where I'd stop to eat. I haven't had the Lucid long enough, but with a Tesla, it generally meant having enough range to continue the trip long before I was done eating. And it's doubtful that I'd postpone charging for another 100 miles or more just because I have the range, if I'm in need of a meal.

As for 80% maximum charge, you have to figure that if people start a trip from home, they can start at 100% relatively easily without wasting their own time. So it comes down to the length of the trip. If I can start a trip close to 100% but I have to start the return trip with 80%, it averages out to more than 80%.

So if I start at 100%, drive at 70-75 mph depending on the freeway, get at least 80% of rated range, then that's over 400 miles of range for me. I'll stop to eat long before that. So it will come down to how well charging stations live up to their theoretical capability. If I could attain 200 miles of range in 12 minutes, then that's about 720 miles of usable range, stopping when I would have stopped rather than at the point where I'd theoretically have to stop. And on the return trip, if I need a charge, charging only enough so that I can get home with 10% remaining range would give me a cushion. The 20%-80% rule is true in general, but it should be no problem going down to 10% and then plugging in at home right away. In real life, I'd stop longer than that to eat. But if I can't find a restaurant near a charging station, with the Lucid I could still likely stop to eat and not charge, and rely on charging at a rest stop IF charging comes close to the theoretical speed, and I start the charge with low range and preconditioning.

 

[Daniel2022AT]

I try to drive 74mph (generally, Midwest and south) and with traffic that can drop to under 65-70 around Chicago, Indianapolis, Louisville, Nashville, Atlanta, etc etc. where heavy traffic is unavoidable. I get about 4.0-4.2 mi/kWh. Using the 10-80% SOC rule, my math is .7x.85 = .6.

That gives me a solid 250 miles of range in my Touring. First leg of the trip starting from 100% SOC yields a range of over 300 which gives great flexibility in trip planning.

What a great vehicle for road trips.

 

[Tesla2.0]

I am a new jersey resident, and it is alien to me how high the speed limits are in much of the west US. For us, going 65 is already above the speed limit, and would likely net an Air about 4.4-4.6 mi/kwh(about 490-515 miles of range on a 19 GT). Then I read how people go in the 90s and sometimes 100s and I get confused, as that does not exist here.

Texas interstate is mostly 75 or 80 mph, some segments is even 85 mph. State Trooper won’t stop for citation unless a car is going above 10+mph in speed limit. Therefore, it is norm to go 90mph in many of Texas highway. My 21” AGT have high highway miles, so to me, this is good 90mph for 3.0x112= 336, 336/456 (18 months degradation) = 0.736, so 2.5 hrs to stop restroom at high speed is very good use case compare to most Tesla I have rented at high speed every 1.5 hours to charge.

 

[Instinctive]

Texas interstate is mostly 75 or 80 mph, some segments is even 85 mph. State Trooper won’t stop for citation unless a car is going above 10+mph in speed limit. Therefore, it is norm to go 90mph in many of Texas highway. My 21” AGT have high highway miles, so to me, this is good 90mph for 3.0x112= 336, 336/456 (18 months degradation) = 0.736, so 2.5 hrs to stop restroom at high speed is very good use case compare to most Tesla I have rented at high speed every 1.5 hours to charge.

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Why only 2.5 hours? Is that to stay in the 20-80% range?

Thank you - this is really helpful for us EV newbies who will be trying eventually to do things like DFW to Durango, CO and such lol