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Constant Driving Speed of a BEV Versus its Range

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From what I remember the most efficient speed for travel is around 25 MPH for an EV, in terms of Wh/m. At freeway speeds, if you want maximum efficiency then drive as slow as you can.

As a practical matter during long interstate trips we drive our old normal +5 - +9 MPH above the speed limit. If we find the charge remaining at destination dropping to 10% or below we slow down, starting with 3 MPH slower than our current speed. That's usually enough to increase the charge remaining at destination. Reducing your speed is a great safety margin that you can control very simply. Beyond that we might follow semi at our normal following distance to further reduce our wind drag. We drive an X, so aerodynamic drag is fairly high, and increases quickly with speed as noted in the above posts.

The advantage of this speed effect is that if you get caught in slow traffic, your range may actually increase. Some of our longest driving stints were made possible by slow Los Angeles traffic! We may be able to skip a supercharger unexpectedly. So no worries about traffic.

You can experiment with A Better Route Planner settings to see if a faster or slower driving speed plus more or less charging time will get you somewhere faster. Back when I last looked at it, the fastest overall time was to drive as fast as possible. That also assumes you charge to a reasonable percentage of capacity, not 100%. It's an interminable wait if you have to charge above 70% to 80%.
 
Very few seem to value time in this thread. Speed wins if one values time over long distances. Using the lower half of battery also provides quicker charging.

Dozens and dozens of solo 1200 mile days. Very easy. Driving 45 doesn't work so well getting to that mile marker however.

Driving 385 miles on a 335 mile 100d isn't as fun as it seems. I think hypermiling went out around the long range cars came out. Like wow one can pee in a bottle and be proud of it.
 
From what I remember the most efficient speed for travel is around 25 MPH for an EV, in terms of Wh/m. At freeway speeds, if you want maximum efficiency then drive as slow as you can.
[ninja'ed by @outdoors]

I agree. That speed is best for energy efficiency. For time efficiency on road trips, Kyle Conner and others (some above) recommend driving fast, pulling into the charger with 5% or less state of charge, and only charging to about 40% or less. Usually just enough to get the next charger with 5%. As he approaches a charger Kyle will adjust his speed to get the expected state of charge down to 2% or so.

This because the charging speed decreases precipitously as the state of charge increases.
 
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[ninja'ed by @outdoors]

I agree. That speed is best for energy efficiency. For time efficiency on road trips, Kyle Conner and others (some above) recommend driving fast, pulling into the charger with 5% or less state of charge, and only charging to about 40% or less. Usually just enough to get the next charger with 5%. As he approaches a charger Kyle will adjust his speed to get the expected state of charge down to 2% or so.

This because the charging speed decreases precipitously as the state of charge increases.
Depends on car. Be careful below 14% or so. Sometimes one loses time as that isn't as fast. It has to ramp. Has gotten better on 3 and Y.

Like pouring a beer fast. You have to stop half wayish.That's how batteries work as well.
 
I believe, the good folks here value time. We only have limited time, and we all value time. As we are always scrambling to find time, we have to make time to enjoy the adventures of this life. That is why, speed is more important than range. How about the idea that every moment of life can be a balance of quality and quantity? A dynamic equanimity is enjoyable, valuable, and venerable all at the same time!
 
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The most efficient freeway speed for a BEV varies depending on the model and the driving conditions. The general consensus is that the energy efficiency starts going down fast at higher speeds as the electric motor's power requirements keep going up. Where can we find a right balance of speed vs efficiency? Today, my wife and I took a ride on my 2023 Tesla MYLR7 at a constant speed of 45 miles per hour. I know, it sounds strange, but yes we did. It was a fun drive, and this largely flat stretch of the freeway was posted at 55 mph. So we were able to legally do 45 mph (The minimum speed on freeways is typically 15 mph below the posted speed limit). We drove a 30 mile stretch at 45 mph. My energy consumption was averaging around 165 wh/mile in the Tesla energy application. At this rate of energy consumption, I averaged out my range mileage data points and came to a total range estimate of about 470 miles. Now, if all other variables of driving dynamics were constant, I'm curious to find out how the range is affected by the vehicle speed. Has anyone compiled a spreadsheet and chartered a graph of their MY/3 at various constant speeds (45, 55, 65,or 75 mph) versus range? Or, we can crowd source it on the TMC forum right here, and report it on this thread. Any MY/3 volunteers?
All I can say is drive under the speed limit, don't drive with a lead foot and try and hypermile, when coming to a stop, red light coast, no brakes. See my
stats.
 
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My sweet spot in 160,000 highway miles is 75mph. That usually puts me 5mph over in some states; 5mph under in others; spot on in the remainder. Still, for me the way I plan and charge it works and I have experimented over the years. I personally think my 2016 MS 90D does better than the 2021 MYLR but I am nearly positive that is unsupportable bias.
I found my 2012 P90 (RWD) Model S (7 seater) had a lifetime efficiency of 286 (150k miles) .... my MYLR7 Y with 40k miles has about 278 wh/mi lifetime... i feel like the S did better than the Y at highway speeds however.. as-in.. it did not seem to suffer as much from high speeds as the Y does but the Y can get more range if you slow roll it

the few times ive rented a 3 it seems better than both in all aspects ... i feel like i can go 80mph in a 3 and still do better than 70mph in my Y (but only have rental car experience)

there was a wise poster on the old tesla forums that said ~77mi/hr was his sweet spot for fastest travel time on road trips in his S ... i imagine exactly which car you have can slightly change your sweet spot (if by sweet spot u mean fastest travel time on long trips)
 
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I believe, a common theme is emerging here:

Based on all that my experience is 75mph is the right speed for me. Five miles an hour more or less over the course of a 12 hour day is 60 miles +/-. If you're worried about range and making it to the next charger, then by all means slow down.
My sweet spot in 160,000 highway miles is 75mph. That usually puts me 5mph over in some states; 5mph under in others; spot on in the remainder. Still, for me the way I plan and charge it works and I have experimented over the years.
and then somewhere around 75 mph was the best speed. Personally,

Today, I experimented myself on a 84 miles round trip, mostly highway driving at 70 to 79 mph. The average energy consumption was 262 Wh/mile, a total of 22 kWh for the trip. Therefore, the "sweet spot" is determined to be 75 mph. Thanks everyone for sharing your real world experience.
 
Huh? Your getting 262 Wh/ Mile at 75?? How. I just tried that, and was easily over 285.
The average consumption can depend on my factors. Your numbers are certainly not bad. Depending upon the weather, headwinds, and other factors, it can be over 300 Wh/mi. Mine was a 84 miles RT average in Chill mode. I was on TACC most of the way, daytime driving, Sunny, 89°F outside, 74°F inside, two average adults, including driver, and no additional load.

Here are my additional findings from another thread:
Wow! A wonderful read indeed. Thank you @LostVector for your painstaking work here. Here are my findings:

1. Tesla Long Range version EVs, Model 3 and Y, both carry 4,416 cells, Panasonic NCA 2170, arranged in 96 groups of 46, and weighs 1,060 pounds (480 kg) in a 0.40 m³ volume; a battery pack density of 150 Wh/kg (540 kJ/kg).

2. For NCA and NCM chemistries, less you discharge your battery, more cycles you’ll get from your battery.

3. Shallow charge and discharge (55-35 or 55-30 SoC), if feasible for routine driving, is the best option for a long battery life.

4. The energy consumption is reasonably good (between 250-280 Wh/mi) for highway driving between 65-74 mph. Above these mph range numbers, the energy consumption goes up dramatically.

5. Normally, an idle Tesla consumes 6-10% of its battery every day. If you put it in Sentry Mode or Dog Mode, it's closer to 1% every hour.

6. Tesla Sleep Mode drains the car’s battery more slowly than if it was “awake." The Sleep Mode consumes just 1% of the battery every day. It does this by switching off any unnecessary systems, including the one that communicates with the Tesla app.

7. Tesla recommends driving or charging your car at least once a week to keep it running smoothly.
 
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The discussion is turning academic! However, the real-world observations are what matters. Based on my experience so far with my Tesla MYLR7 2023, I'm expecting no more 25 to 30 miles of driving range for every 10% battery consumption. If my SoC range is 80%, I can travel 150 to 200 mi, before hitting the 20% SoC, the orange colored, initial low battery warning.

I don't think it's very flattering. Do you all agree with this assessment?

PS: I'm using a new and improved battery charging regimen.
My Charging Best Practices:
BEV - Maintaining Li-ion Battery.png

Maintaining Li-ion (NCM & NCA) Batteries - Real-world Recommendations for BEVs. The illustrated partial recharge cycle recommendations were revised recently in light of my extensive conversations with experts and long-time Tesla owners. LFP batteries should be charged to 100% at least once every week.
 
10% of the battery equating to 25 to 30 miles of highway driving sound right. When traveling don't be concerned if the battery SOC is 10% when you stop to charge. That is an additional ~25 miles of usable range. Lower your highway speed by 5 MPH for an additional 8% or more increase in efficiency and range. Those two changes will net you ~45 miles of additional range.

If you still require additional reassurance and range you can lower your speed by another 5 MPH and turn off the AC (just use the HVAC fan) for an additional 13% increase in efficiency and ~32 miles in additional range (~77 miles total additional range).

It is better to use these range extending techniques early in a trip leg, gradually increase your speed if you want as you get closer to your next charging location or destination. The Energy Screen will track your consumption and projected range and arrival state of charge.
 
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