Range at altitude

[xxiii]

Another thing that occurred to me to wonder about:

Is there a significant change in range (or range loss) at 80mph (or any speed), at sea level, and say, 4500 feet (where I live)?

The atmosphere is thinner, so drag should be less, and therefore 80 shouldn't be quite as bad, but is the difference non-trivial? (given that people get excited when a software update changes the total range from 260 to 262 miles, which admittedly is important when you can see the charging station ahead just as your meter goes from 1% to 0%...)

Given that the shape and presence of door handles is enough to worry about, I would think this actually is a significant factor.

And are we going to find out that some manufacturers do all their range testing in the Himalayas?

Next YouTube comparison: range in the rocky mountains (if they can find somewhere flat that's long enough), vs range on the pacific coast highway.

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[Teleks]

I can't say much about how much the thinner air reduces drag. Probably the physics behind it is pretty trivial and one could calculate that. But I think it wouldn't be very much.

I think the much more important point here though is that there is generally no negative effect of altitude on EVs, which is not at all the case for ICE vehicles. Combustion engines do significantly loose efficiency with increasing altitude due to the lower air pressure and less oxygen.

 

[RickMachE]

There is an impact from climbing to that altitude. Once there, I'm sure someone here will show the formula (Sheldon, you around?) that shows that the inverse of Pi to the nth position shows a correlation with the flagometer and yes, you get slightly more range.

 

[Fremont Kid]

Yes, the effect is fairly trivial. Extend range by driving slower to reduce drag. The laws of physics aren't suspended at higher altitudes.
Performance at higher altitudes became a hot topic when Bob Beamon long jumped 29' 2 1/4" at the Mexico City Olympics which is at 7,000 ft. However, discus and javelin records were not set there. Also, people had been competing at high altitude sites for decades w/o other phenomenal results. Bob just hit the perfect jump. Thanks for tolerating my stroll down memory lane of the most singular athletic achievement in Olympic history. If you have never seen, find on YouTube. Won't be disappointed.

 

[Mach-Lee]

Drag is proportional to air density. At 4500', the air density is about 85% of sea level. That translates to roughly 10% more range at highway speed.

The door handles are strategically located in the wake of the mirrors so they don't have a big effect on drag.

 

[The Electric Duo]

I can't say much about how much the thinner air reduces drag. Probably the physics behind it is pretty trivial and one could calculate that. But I think it wouldn't be very much.

I think the much more important point here though is that there is generally no negative effect of altitude on EVs, which is not at all the case for ICE vehicles. Combustion engines do significantly loose efficiency with increasing altitude due to the lower air pressure and less oxygen.

I did some Googling about that when we drove to the top of Mount Evans (over 14,000 feet). The general rule of thumb is 3% HP loss for ever 1,000 feet of elevation gain. So at the top of Mt Evans, that is a 42% loss for an ICE car!

But even at Denver altitude, it makes a big difference. The Mach-E GT PE has 480 HP at sea level and in Denver. The Mustang Dark Horse will have 500 HP at sea level and 420 in Denver (mile high marijuana joke not intended). ?

 

[Kamuelaflyer]

There is an impact from climbing to that altitude. Once there, I'm sure someone here will show the formula (Sheldon, you around?) that shows that the inverse of Pi to the nth position shows a correlation with the flagometer and yes, you get slightly more range.

This. I live at 4400 ft on the side of a dormant volcano. My trip to the grocery store this morning was 17 miles each way. The drive to the store resulted in a 1% soc decrease (80% to 79%). The return to altitude was 9% on the same route. AWD ER driving the speed limit (50 mph and 35 mph) cause it’s Sunday morning and people are functionally asleep while driving.

Whatever minuscule amount of drag decrease I get for driving around here at 4400 feet plus is lost in the energy used getting here.

 

[Thor2j]

I can tell you a few things living at 8000 feet elevation. My GT non PE did 0-60 in 3.56 seconds at 8500 feet verified by draggy.
When I drive my raptor on a 3 hour trip at 75 mph in the mountains I get over 20 mpg. When I drove at same speeds in Florida I got 16.5.

Thin air makes huge difference.

 

[xxiii]

[...]no negative effect of altitude on EVs, which is not at all the case for ICE vehicles.[...]

Except they do get to get away with using lower octane gas, at least. (Apparently this is controversial now as well, as I search it just now).

 

[Teleks]

@Thor2j : Interesting!

I guess my comment was wrong about both, drag and ICE efficiency. For ICE I guess it's not the efficiency (mpg) that's affected, but just the power, like @Mach-E VLOG mentioned. I'm surprised efficiency is not compromised though!

Edit: Or not! Maybe I was right haha. As @Thor2j explains below, the Raptor is turbocharged, which means it's affected differently by altitude!

 

[xxiii]

[...]Combustion engines do significantly loose efficiency with increasing altitude due to the lower air pressure and less oxygen.

Is this why my ICE car never achieves its EPA rating? (my driving and whatever loopholes exist in the rating process notwithstanding)
(4500' where I live)

 

[Thor2j]

Is this why my ICE car never achieves its EPA rating? (my driving and whatever loopholes exist in the rating process notwithstanding)
(4500' where I live)

My ICE vehicle far exceeds it's advertised mpg driving between 8 and 12k feet.

 

[Thor2j]

I did some Googling about that when we drove to the top of Mount Evans (over 14,000 feet). The general rule of thumb is 3% HP loss for ever 1,000 feet of elevation gain. So at the top of Mt Evans, that is a 42% loss for an ICE car!

But even at Denver altitude, it makes a big difference. The Mach-E GT PE has 480 HP at sea level and in Denver. The Mustang Dark Horse will have 500 HP at sea level and 420 in Denver (mile high marijuana joke not intended). ?

This loss in power for ice vehicle applies mainly to naturally aspirated motors, turbo charged and supercharged motors have far less loss.

 

[xxiii]

My ICE vehicle far exceeds it's advertised mpg driving between 8 and 12k feet.

Guess it's my driving then.

 

[Teleks]

Very interesting topic and much more complex than I originally thought haha.

To summarize:
-Drag might play a big role. As @Thor2j says, his ICE Raptor is more efficient at high altitudes
-Generally combustion engines are less powerful at high altitudes. Very well known phenomena and rule of thumb is 3% power loss per 1000 ft of elevation. From what I found this also affects efficiency, i.e. mpgs in a negative way.
-However, this does not apply for turbo charged engines. They don't need the atmosphere to compress the air - the turbo does it for them. From what I found, they are basically entirely unaffected. Which explains why Thor2j doesn't have a problem with his Raptor

So @xxiii , it might not be your driving!

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