Range at high speeds?

[Tom32]

I saw the article about ~70mph Taycan test doing ~300miles, but has anyone stumbled upon some test/info or tried themselves how range would be affected at higher speeds, let's say 125 mph (200km/h)? I'm wondering how much percentage wise that affects the range.

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[KoSoVaR]

I saw the article about ~70mph Taycan test doing ~300miles, but has anyone stumbled upon some test/info or tried themselves how range would be affected at higher speeds, let's say 125 mph (200km/h)? I'm wondering how much percentage wise that affects the range.

Here you go!

Based on 5 years with a few Model X performance versions, it’s a big hit on the battery. I’d say on a 100kWh pack you start to see 1mile per 1%, or 100 mile range going in to higher speeds.

It doesn’t seem to be a linear efficiency loss. Once you get past the efficiency speed (70Mph), it goes downhill very fast.

 

[kort]

I find it very hard to buy the 300 mile range @70 mph. on a recent trip, running between 70 and 77 MPH, I barely eked out 200+ miles consumption was between 3.1 and 3.4 mile per kwh.
at 125 mph you will consume far more and go far less.
when road tripping there is a balance you need to have between speed and range.

 

[Jrkennedy37]

I find it very hard to buy the 300 mile range @70 mph. on a recent trip, running between 70 and 77 MPH, I barely eked out 200+ miles consumption was between 3.1 and 3.4 mile per kwh.
at 125 mph you will consume far more and go far less.
when road tripping there is a balance you need to have between speed and range.

3.1 is 260 mile range
3.4 is 290 mile range

The reality is a roadtrip only allows you to charge to 80-90% so you’re looking at stretches 200-240 mile without putting yourself at significant risk while traveling 70-85mph. Above that is being stubborn, not rational.

 

[daveo4EV]

after 40 mph most of the power is due to aero-drag - aero-drag has a V^Squared component - it is NOT linear - it is increasingly expensive for each mph you go over about 40-45 mph - up until then it's mostly the physics cost to move mass - after than its _ALL_ aero and it is is not linear…

if you want to extend range drive slower - it makes a huge difference

when I owned a Model S P85D there is segment on I-5 south from Harris Ranch to the base of the grapevine -between superchargers - if you go 80 mph you cna make it with about 5% battery left - but if you go 68 mph it takes 8 min longer, but you arrive with 20% battery - arriving with 20% battery means you are there for 10 min less time than arriving with 5% battery - so it's actually 2 min faster to drive 68 mph if you include charging time due to increased consumption.

speed is the range killer - and more importantly if you go slower you can drive further and have fewer charging stops - so you can turn a 2 stop segment into 1 one stop segment and actually have a higher average speed for the entire segment.

if the taycan can go 300 miles @ 70 mph it can go 400 miles at 40 mph - and 80 miles at like 140 mph - but the battery will overheat and the software will chop power long before you go 80 miles…

 

[herminal]

Actually it has been tested that around 160-180kph is the best cruising speed for EV’s, permitted there are enough fast chargers around and the car in question can charge at high speeds.

you could drive at 90kph but the driving time would double and charging from 10-80% takes only 20 mins.

the faster the car can charge the more advantageous it is to drive faster

for example : 1 hour at 200kph and a 30 min charge session then again 200hph for 1 hour means average speed of 160kph and 400km covered in 2.5 hours.

at 100kph you would only cover 250km in 2.5 hours..

Seems obvious to me that driving slow is the dumb thing to do ?

driving vmax on the other hand, not a good idea.. only 120km range.

 

[SwissTaycan]

Can we start a new post: Fun at high speeds?

 

[WuffvonTrips]

I saw the article about ~70mph Taycan test doing ~300miles, but has anyone stumbled upon some test/info or tried themselves how range would be affected at higher speeds, let's say 125 mph (200km/h)? I'm wondering how much percentage wise that affects the range.

Assuming that the vast majority of the required power would be needed to overcome aero drag, the range at 125 mph would be 31% of the range at 70mph. (drag force being proportional to the square of velocity)

 

[mcr21]

after 40 mph most of the power is due to aero-drag - aero-drag has a V^Squared component - it is NOT linear - it is increasingly expensive for each mph you go over about 40-45 mph - up until then it's mostly the physics cost to move mass - after than its _ALL_ aero and it is is not linear…

if you want to extend range drive slower - it makes a huge difference

when I owned a Model S P85D there is segment on I-5 south from Harris Ranch to the base of the grapevine -between superchargers - if you go 80 mph you cna make it with about 5% battery left - but if you go 68 mph it takes 8 min longer, but you arrive with 20% battery - arriving with 20% battery means you are there for 10 min less time than arriving with 5% battery - so it's actually 2 min faster to drive 68 mph if you include charging time due to increased consumption.

speed is the range killer - and more importantly if you go slower you can drive further and have fewer charging stops - so you can turn a 2 stop segment into 1 one stop segment and actually have a higher average speed for the entire segment.

if the taycan can go 300 miles @ 70 mph it can go 400 miles at 40 mph - and 80 miles at like 140 mph - but the battery will overheat and the software will chop power long before you go 80 miles…

Overall range is probably one of the last considerations for most Taycan buyers, but if you do end up in a pickle during a longer road trip (happened to me once this summer in the hilly parts of Southern France en route to Barcelona), driving slow and coasting whenever possible definitely make a big difference

 

[Jrkennedy37]

if the taycan can go 300 miles @ 70 mph it can go 400 miles at 40 mph - and 80 miles at like 140 mph - but the battery will overheat and the software will chop power long before you go 80 miles…

Actually it has been tested that around 160-180kph is the best cruising speed for EV’s, permitted there are enough fast chargers around and the car in question can charge at high speeds.

Anecdote from my service guy so take with grain of salt - of the two full battery replacements he’s done, the first was on a car delivered a few hours earlier that was immediately taken on a high speed run from Dallas down to San Antonio. The car keeps all records of what happened so they were able to see the driver was pushing 160 mph for long periods down I-35 (this was early covid so roads were empty) interspersed with fast charges. He never gave the battery a chance to cool down in between and ruined it.

 

[Chris8536]

I go 90 SF to LA and you’re already at 200 mi range. Averaging 70 ive never gotten more than 220. Don’t know how anyone got 309

 

[herminal]

Anecdote from my service guy so take with grain of salt - of the two full battery replacements he’s done, the first was on a car delivered a few hours earlier that was immediately taken on a high speed run from Dallas down to San Antonio. The car keeps all records of what happened so they were able to see the driver was pushing 160 mph for long periods down I-35 (this was early covid so roads were empty) interspersed with fast charges. He never gave the battery a chance to cool down in between and ruined it.

LOL that seems ludicrous and bad development… I know for a fact that the battery gets cooled and/or heated to get best charging speeds. If the battery gets too hot the charging will slow down.. if the battery gets too hot will driving the power will be reduced to cool down the battery.. so normally the battery can’t get too hot

 

[daveo4EV]

I can use 50% battery @ Laguna Seca in about 8 laps - that's 17.904 miles + some distance to get on/off the track

at speeds great than 100 mph I would suggest the Taycan is less than 100 miles range - maybe even less than 75 miles range.

in my Model 3 when going faster than 100 mph I could watch the battery percentage drop in real time…about every 1/4 mile…

 

[Jhenson29]

tldr; 146 miles

I didn't double check any of this so there's a non-zero chance of errors, which I will correct if pointed out or if I find myself.

Some basics
If energy is 83.7 kWh (user-accessible battery capacity) and distance is equal to 300 miles, we can say that the car used 0.279 kWh per mile or 27.9 kWh per 100 miles.

Because work (energy use) is equal to force times distance, energy per distance is a unit of force. i.e. the 27.9 kWh/100mi tells us something about the force required to move the car (although not entirely because not all of the energy was used for force).

Note that one kWh/100mi is equal to about 22.4 N, but I actually like kWh/100mi better for this exercise, so we'll keep it. And this is 17.3 kWh/100km going 482.8 km at 112.6 kph for the metric people playing along at home.

Drag is a drag...
The dominant change in force for a change in speed will be drag. The drag force is equal to the coefficient of friction times the area times the fluid density times the speed squared.

Porsche has published the drag coefficient as 0.22 Cd and the frontal area as 2.33 m^2.
Air density is 1.2 kg/m^3.

Other standard units are meters per second and, with an additional scalar of 0.5, the equation yields newtons. But we don't want N or m/s. We want kWh/100mi and mph.

So, we'll plug in the numbers for air and the Taycan, add some other scalars to convert units to our (my) preference, and we have the below:

Drag force in kWh/100mi for a given mph:
mph^2 * 0.00273

And the metric folk: kWh/100km for a given kph:
kph^2 * 0.00066

Okay, so now we can say, at 70mph, the drag force is 70*70*0.00273 or about 13.3kWh/100mi. (8.3kwh/100km).

So, of the 27.9kWh/100mi consumption rate, 13.3kWh/100mi is from drag.

This leaves 14.6kWh/100mi that we won't change as speed changes*.
(9.1 kW/100km)

Now, finally, for the OP's question, how does the range change at 125mph?

125*125*0.00273 = 42.7 kWH/100mi ? (26.7 kWh/100km)
This is the new drag force to replace the 13.3kWh/100mi at 70mph.

Add the 14.6 kWh/100mi and we're at 57.3 kWh/100mi. (35.8 kWh/100km)

Going back to battery energy of 83.7 kWh divided by 57.3, and times 100, we get....

146 miles (234 km)

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*This 14.6kWh/100mi does likely change some with speed. For example, there are some time dependent energy uses such as AC that improve this number at higher speed. Rolling resistance may change some as tire temperature changes from the different speed. But as others have pointed out, the drag is by far the largest factor...and also most straightforward to just calculate.

 

[Gru]

almost 40 kWh/100 km driving at (almost) 100mph during 24h: range won’t exceed 130 miles…

record

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