Electric cars and cooling drag

[aerohead]

Originally Posted by JulianEdgar

Well, where is your citation to support that? There aren’t any! I go on published evidence, not guesswork.

To a pedantic non-engineer it could appear that way.
Fifteen years ago was the last time I paid a professional engineer a consulting fee.
At that time, $ 135 / hour was the going rate, which included a 1-hour minimum.
The reason some professionals have refused to help you, or have remained mute when queried about your upcoming book, is that you may be unaware of what you're asking them to volunteer, with respect to their real costs.
It's unfortunate that you didn't complete a mechanical engineering program. It would have provided the insights which escape you.
I'd recommend you add someone to your team / network. Someone like Louis Duncan might set you straight.

[aerohead]

Originally Posted by AeroMcAeroFace

Exactly, at 1mph, almost all drag is rolling resistance. This statement is of no use.

"No one has been able to show any data on BEV cooling drag as a percentage of total drag that rebuts what I wrote in the first post."

Julian, while I agree, it may be worth specifying aerodynamic drag, because total drag is both linear (rolling resistance) and exponential (aerodynamic).

aerohead is correct when he writes that at some velocity 1.4% of total drag is cooling, however that includes rolling resistance. Ignoring rolling resistance is essential to get correct numbers.

Quit now while you have a slim chance to save face.

[aerohead]

Originally Posted by JulianEdgar

Not at all. I saw a statement often made here that didn’t seem to be supported by the facts, and drew people’s attention to that.

No one has been able to show any data on BEV cooling drag as a percentage of total drag that rebuts what I wrote in the first post.

Instead, there’s been a few good posts.... a huge amount of irrelevant and / or misinformation posted. Par for the course here.

That's engineering. Something you don't do. And something your sources don't fully account for.
It's utter folly to present an argument that's unsupportable.
I recommend a deep dive into the topic before you spew anymore quarter-baked ideas into the public domain. Irrelevant and misleading by default.
As an aside, you might want to contact British Petroleum, Royal Dutch Shell, and CALTEX. Their lobbyists would pay handsomely for materials such as yours.

[JulianEdgar]

Originally Posted by aerohead

That's engineering. Something you don't do. And something your sources don't fully account for.
It's utter folly to present an argument that's unsupportable.
I recommend a deep dive into the topic before you spew anymore quarter-baked ideas into the public domain. Irrelevant and misleading by default.
As an aside, you might want to contact British Petroleum, Royal Dutch Shell, and CALTEX. Their lobbyists would pay handsomely for materials such as yours.

No one has been able to show any data on BEV cooling drag as a percentage of total drag that rebuts what I wrote in the first post.

Aerohead is simply back to posting his own theories, fighting tooth and nail to deny that he has been writing quite misleading material about this topic.

I have met people like him before: people who could never write anything that was properly published and subject to expert review. After such a review, there’d be nothing left to publish!

Ah, the joys of misinformation on web discussion groups.

[aerohead]

You don't recognize rebuttal when it visits. Why waste any more time. We keep waiting for data on cooling systems. Do you actually have any?

[JulianEdgar]

Originally Posted by aerohead

You don't recognize rebuttal when it visits. Why waste any more time. We keep waiting for data on cooling systems. Do you actually have any?

Yes. I am the only person here who has quoted citations from the technical literature that shows percentage cooling drag of BEVs (ie percentage of total aerodynamic drag).

You’ve posted a wide range of irrelevant material, your own theories, and various amounts of typical Aerohead misinformation.

So, situation as normal for your contributions.

[ME_Andy]

I'll drop a couple more data points.

Car - Gas Cd / EV Cd
2019 Kona 0.34 / 0.29 (different wheels & underbody)
2014 Spark 0.357 / 0.326
2014 Cruze/Volt 0.30 / 0.28

[JulianEdgar]

Originally Posted by ME_Andy

I'll drop a couple more data points.

Car - Gas Cd / EV Cd
2019 Kona 0.34 / 0.29 (different wheels & underbody)
2014 Spark 0.357 / 0.326
2014 Cruze/Volt 0.30 / 0.28

That information does not tell us what the cooling drag proportion of total Cd is for the listed cars. So basically it’s irrelevant - unless you are suggesting that the change in Cd between the ICE and BEV models is due solely to the change in cooling drag (which it isn’t). The Cruise / Volt comparison is particularly ridiculous - the two cars have completely different shapes.

Again, just sewing the seeds of confusion.

[planetaire]

Hi

I use since 10 years a toyota prius in electric mode only. I close the front totally except in summer when temperature is say 30°C or more. When the front grill est blocked, the drag needed due to colling is zero Newton and zero percent of the total drag.
At the opposite, previously, 11 - 12 years ago I drove the same car in hybrid mode, I can very rarely close the front grill, the engine could quickly goes over 95°C.
So I am sure that in electric mode this car need much less cooling then in gazoline mode.

A second point is that pourcentage is not the value I would prefer, Newton is more suitable because for a car having a gazoline version and an electric version, the Cd of the electric model is lower (E-niro... for exemple). So using a pourcentage of a number lower is not a very good way if the purpose is to compare two type of energy.

A third point is that actual ev car have a grill shutter (Ioniq, ID3, ID4...). If you want to know the cooling drag, Newton or %, you need to know when this grill is open or not.

[JulianEdgar]

Originally Posted by planetaire

Hi

I use since 10 years a toyota prius in electric mode only. I close the front totally except in summer when temperature is say 30°C or more. When the front grill est blocked, the drag needed due to colling is zero Newton and zero percent of the total drag.
At the opposite, previously, 11 - 12 years ago I drove the same car in hybrid mode, I can very rarely close the front grill, the engine could quickly goes over 95°C.
So I am sure that in electric mode this car need much less cooling then in gazoline mode.

A second point is that pourcentage is not the value I would prefer, Newton is more suitable because for a car having a gazoline version and an electric version, the Cd of the electric model is lower (E-niro... for exemple). So using a pourcentage of a number lower is not a very good way if the purpose is to compare two type of energy.

A third point is that actual ev car have a grill shutter (Ioniq, ID3, ID4...). If you want to know the cooling drag, Newton or %, you need to know when this grill is open or not.

1. Closing off the cooling in low-power electric mode in a Prius tells us nothing relevant to this discussion (which is about BEVs), does it?

2. Cd values (or percentages of total Cd) are used for cooling systems because it is a coefficient. If we used Newtons, we'd need to specify speed. We can easily work out the force for any car for which we have speed, area and cooling drag Cd.

3. Shutters apply equally to all cars these days - ICE, Hybrid, BEV. Cooling drag is with the shutters open ie the cooling system working.