Confirmation: fastest way to drive a Tesla

bwilson4web

bwilson4web

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On a trip to Colorado, they point out that many short, fast charging sessions are the fastest way to make miles in a Tesla. By charging at the peak rate, the Tesla makes more time than wasting time in the slower, charge taper.

Bob Wilson
 
Yep, watched that one last night, good info.

One thing that jumped out at me, they have no reservations to speeding. I'm not talking +10 mph either, there are several times the speedometer shows 100+. Kind of crazy to talk about the car being less efficient while going those kinds of speeds. I've been on some of those roads across Missouri and Kansas, they arent built for 100+mph travel. But, just my opinion.
 
Yeah, the best strategy for traveling long distances as quickly as possible, using the Supercharger network in a Tesla car -- base on actual experience, not just theory or armchair engineering -- is to run the car down to about 10% before hitting the next Supercharger, and then charging just enough to make it to the next planned stop, plus 10% for a safety margin.

Tesla cars charge fastest when they battery pack is as depleted (near 0%) as possible.

Speeds of over 100 MPH, really??? The energy drain per mile at that speed must be something terrific! (Well okay, obviously less since it's metric... ;)) ...since aero drag goes up as the square of speed. I wonder what the point of diminishing return is; the speed above which you actually lose time because you have to spend more time charging to make up for the excess energy loss.
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Pushmi-Pullyu said:
. . . <good stuff> . . .

Speeds of over 100 MPH, really??? The energy drain per mile at that speed must be something terrific! (Well okay, obviously less since it's metric... ;)) ...since aero drag goes up as the square of speed. I wonder what the point of diminishing return is; the speed above which you actually lose time because you have to spend more time charging to make up for the excess energy loss.
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The energy required increases by the cube of the speed so it is really draining. But their driving strategy is to hit every SuperCharger in the 5-10% range. I find 5% (~10 mi) is my lowest limit because when it falls below 5%, it starts shutting things down like HVAC. Their speed is more a function of distance between SuperChargers and a couple of times they reported 'accidental' over charging. You know, walking the dogs, getting something to eat . . . taking a 'nap'.

Bob Wilson
 
bwilson4web said:
The energy required increases by the cube of the speed so it is really draining.
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I've always found that quite confusing. Drag only increases as the square of speed -- or so I see claimed at multiple websites -- but the energy required to propel the car goes up as the cube of speed.

Maybe that makes sense to you, Bob; you're an engineer, but I'm not.

Perhaps the energy required goes up faster than the drag, as speed increases, because some of the energy goes to increased momentum, or kinetic energy? But no, that would only take increased energy to reach the higher speed, not to maintain it.

Anyway, none of that addresses the main question I have, which is what the optimal speed is for driving a Tesla car down the highway, using only Superchargers to extend the range. My guess is that speeds in excess of 100 MPH would be less efficient in terms of average speed (including stops for recharging), but that's just a guess and I'm certainly willing to be told I'm wrong.

But yes, I realize it's at least partly dependent on the distance between Supercharger stations, so there may not be a generalized answer to that question.
 
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Drag is a force although in this case, a function of speed, the distance over time.

Energy is the force over distance. So distance occurs twice and when you do the algebra, the cube of the speed.

I’m at a bar with a date, my wife. I’ll follow up with more details.

Bob Wilson
 
Pushmi-Pullyu said:
I've always found that quite confusing. Drag only increases as the square of speed -- or so I see claimed at multiple websites -- but the energy required to propel the car goes up as the cube of speed.

Maybe that makes sense to you, Bob; you're an engineer, but I'm not.

Perhaps the energy required goes up faster than the drag, as speed increases, because some of the energy goes to increased momentum, or kinetic energy? But no, that would only take increased energy to reach the higher speed, not to maintain it.

Anyway, none of that addresses the main question I have, which is what the optimal speed is for driving a Tesla car down the highway, using only Superchargers to extend the range. My guess is that speeds in excess of 100 MPH would be less efficient in terms of average speed (including stops for recharging), but that's just a guess and I'm certainly willing to be told I'm wrong.

But yes, I realize it's at least partly dependent on the distance between Supercharger stations, so there may not be a generalized answer to that question.
Click to expand...

Some guys on the autobahn drove almost 2000 miles in 24 hours in a LR M3. They hit 100-110mph whenever they could and charged from 10-50%. I would think if your going for best possible speed over multiple charge stops 100-120mph would be best for model 3. If you had a V3 supercharger then it would be even faster. I’m not even going to try doing the math but it shouldn’t be hard for an engineer/student to figure out.


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HagerHedgie said:
Some guys on the autobahn drove almost 2000 miles in 24 hours in a LR M3. They hit 100-110mph whenever they could and charged from 10-50%. I would think if your going for best possible speed over multiple charge stops 100-120mph would be best for model 3. If you had a V3 supercharger then it would be even faster. I’m not even going to try doing the math but it shouldn’t be hard for an engineer/student to figure out.
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There are several approaches:
  1. benchmark - plot the consumption vs speed and use 63 mph as the base speed:
    mph_miles.jpg
    The the expected distance to next charging station. Select a target speed that reaches that next station starting with 100% SOC. Scale the chart distance by the SOC you will accept and the problem is solved. Note this graph is car specific, Standard Range Plus Model 3, March 26, 2019. However, a future firmware release will requires a new benchmark.
  2. use built-in trip estimator - this has a line showing how many miles/SOC will be in the car driving at 63 mph. Add extra charge and then drive like heck while monitoring the actual consumption line. Adjust speed up or down to arrive with a minimum range left like 10 miles.
  3. use charging benchmark - there has already been a change in the EV charging profile which is firmware dependent:
    Super_210.jpg
    All of the range estimates are at 63 mph. Based on the two-tier charging model, charge down to a 40 kW rate, ~30 min. Regardless, of speed goal, 15-30 minutes is the sweet stopping point.

Bob Wilson
 
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bwilson4web said:
There are several approaches:
  1. benchmark - plot the consumption vs speed and use 63 mph as the base speed:
    mph_miles.jpg
    The the expected distance to next charging station. Select a target speed that reaches that next station starting with 100% SOC. Scale the chart distance by the SOC you will accept and the problem is solved. Note this graph is car specific, Standard Range Plus Model 3, March 26, 2019. However, a future firmware release will requires a new benchmark.
  2. use built-in trip estimator - this has a line showing how many miles/SOC will be in the car driving at 63 mph. Add extra charge and then drive like heck while monitoring the actual consumption line. Adjust speed up or down to arrive with a minimum range left like 10 miles.
  3. use charging benchmark - there has already been a change in the EV charging profile which is firmware dependent:
    Super_210.jpg
    All of the range estimates are at 63 mph. Based on the two-tier charging model, charge down to a 40 kW rate, ~30 min. Regardless, of speed goal, 15-30 minutes is the sweet stopping point.

Bob Wilson
Click to expand...

If your going for speed 15-30 min stops are definitely ideal. I was wondering what the ideal driving speed would be. In real world conditions you’re probably not saving much time going more than 80 to 90 because you really lose range quick the faster you go.


Sent from my iPhone using Inside EVs
 
HagerHedgie said:
If your going for speed 15-30 min stops are definitely ideal. I was wondering what the ideal driving speed would be. In real world conditions you’re probably not saving much time going more than 80 to 90 because you really lose range quick the faster you go.
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My model that I benchmarked shows an indicated 73 mph gives 60 mph block-to-block. I plan to validate the model at 77 mph over 1,000 km (625 mi) giving 65 mph block-to-block. But I've ordered the CANbus-to-OBD kit for detailed metrics. I also want to run it on a 'Standard Day' to make sure the numbers are accurate.

Bob Wilson
 
bwilson4web said:
My model that I benchmarked shows an indicated 73 mph gives 60 mph block-to-block. I plan to validate the model at 77 mph over 1,000 km (625 mi) giving 65 mph block-to-block. But I've ordered the CANbus-to-OBD kit for detailed metrics. I also want to run it on a 'Standard Day' to make sure the numbers are accurate.

Bob Wilson
Click to expand...

It sounds like a calculus problem I could’ve figured out 20 years ago but trying different speeds in 5 mph increments would work. I’d like to see somebody test one at an oval with a supercharger.


Sent from my iPhone using Inside EVs
 
It is a simple problem. Imagine a circle with two perfectly placed SuperChargers. Now stretch that circle so each side is ~50-100 yards apart. Put Interstate signs on each side and drive at USA traffic speed. For example, Athens AL and Dickson TN.

Bob Wilson
 
bwilson4web said:
It is a simple problem. Imagine a circle with two perfectly placed SuperChargers. Now stretch that circle so each side is ~50-100 yards apart. Put Interstate signs on each side and drive at USA traffic speed. For example, Athens AL and Dickson TN.

Bob Wilson
Click to expand...

I was thinking more along the lines of max average speed disregarding speed limits.
If your sticking to sensible speeds than 10-15 minutes of charging, starting around 10% SOC would be ideal. As soon as the charge rate drops under 100kw get back on the road.


Sent from my iPhone using Inside EVs
 
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