Electric cars and cooling drag

[aerohead]

Originally Posted by AeroMcAeroFace

The parameters are cooling drag as either a proportion/percentage of aerodynamic drag or Cd change. This is ignoring other changes that may occur as a result of becoming an EV.

Comparing ICE and EV variants doesn't help, because it is more than just the cooling that has changed, the gearbox is different, they may use narrower tyres, different rims, there is no fuel tank or exhaust, the battery pack may form an undertray where previously there wasn't one etc.

There is no need to "fix" anything, aerodynamic drag is proportional to speed squared, that is why we have Cd

1) an example: are shutter positions, if present, accounted for?
2) is air conditioning 'conventional' or 'heat pump?'
3) is radiator and condenser series, or parallel?
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The act of presenting ICE and BEV variants allows an observer to 'focus' in on the existing variations which lead to the differences, in order to parse out the specifics. I see no harm, only the contrary.

[aerohead]

A basic understanding of BSFC and BSFC-e is critical to a deep, comprehensive, and rewarding understanding of the heat flux dynamics between the two flavors of vehicles.

[AeroMcAeroFace]

Originally Posted by aerohead

1) an example: are shutter positions, if present, accounted for?
2) is air conditioning 'conventional' or 'heat pump.'
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The act of presenting ICE and BEV variants allows an observer to 'focus' in on the existing variations which lead to the differences, in order to parse out the specifics. I see no harm, only the contrary.

Isn't the point though? When the focus is specifically targeting cooling drag it is impossible to compare a cars cooling drag by looking at its Cd in ICE and EV form. You can't get the specifics of where the change comes from, that cannot be extracted from the data and so how can it allow the observer to " 'focus' in on the specifics" ?

If I modify my car, and change the cooling system, the undertray, the wheels and the rims and then say "I have lowered drag by 10%", you don't know which mods did what amount of the change, some could be increasing drag, some could decrease.

I see the interest in the comparisons, and thanks for providing them, but I disagree completely that you can get specifics from a Cd change.

[aerohead]

Originally Posted by AeroMcAeroFace

Isn't the point though? When the focus is specifically targeting cooling drag it is impossible to compare a cars cooling drag by looking at its Cd in ICE and EV form. You can't get the specifics of where the change comes from, that cannot be extracted from the data and so how can it allow the observer to " 'focus' in on the specifics" ?

If I modify my car, and change the cooling system, the undertray, the wheels and the rims and then say "I have lowered drag by 10%", you don't know which mods did what amount of the change, some could be increasing drag, some could decrease.

I see the interest in the comparisons, and thanks for providing them, but I disagree completely that you can get specifics from a Cd change.

The comment that BEVs can have larger cooling needs than ICE vehicles requires some fleshing out.
My comments are meant to provide some context when considering a remark like that.
We're not far enough along yet in the conversation to consider modifications.

[freebeard]

2) is air conditioning 'conventional' or 'heat pump.'

What would be the working fluid to 'supercharge' the cooling system and run a hotter [glowing red ceramic Meredith Effect] radiator?

[aerohead]

Originally Posted by freebeard

What would be the working fluid to 'supercharge' the cooling system and run a hotter [glowing red ceramic Meredith Effect] radiator?

It may be that you'd be upping the working pressure of the cooling system in order to prevent the working fluid from flashing off.
It looks like you're in the 800-C, to 900-C range.

[aerohead]

Originally Posted by JulianEdgar

I've noticed that a few people here seem to believe that the cooling system drag of battery electric vehicles is very low, or even zero.

I don't think that is right.

In the research for my upcoming book on car aerodynamic history, I've looked at the percentage cooling drag of the Tesla Model S and the Porsche Taycan.

The Tesla's cooling drag calculates at 8 per cent, and the Taycan's at 16 per cent.

Obviously, these - and other modern cars - can decrease that when cooling isn't needed by closing shutters. But the fact remains that cooling drag on electric cars appears to be similar, or even greater, than on traditional internal combustion engine cars.

Seems like the only reasonable path to a conclusion like this would be a direct, side-by-side comparisons to ICE variants of the Tesla Model S and Porsche Taycan Turbo.

[Isaac Zachary]

I used to think cooling systems were cool but now I think they're a drag.

[JulianEdgar]

Originally Posted by AeroMcAeroFace

Isn't the point though? When the focus is specifically targeting cooling drag it is impossible to compare a cars cooling drag by looking at its Cd in ICE and EV form. You can't get the specifics of where the change comes from, that cannot be extracted from the data and so how can it allow the observer to " 'focus' in on the specifics" ?

If I modify my car, and change the cooling system, the undertray, the wheels and the rims and then say "I have lowered drag by 10%", you don't know which mods did what amount of the change, some could be increasing drag, some could decrease.

I see the interest in the comparisons, and thanks for providing them, but I disagree completely that you can get specifics from a Cd change.

Yes, it seems that some people struggle with the concept of what 'percentage cooling drag' means.

To make what I hope is an obvious point, even if cooling drag stayed the same, as overall Cd of cars drop, the percentage cooling drag will increase.

Most of the other data that is being quoted here is pointless since the discussion is (was?) about percentage cooling drag. And the available data shows that:

1) On current BEVs, percentage cooling drag is nowhere near zero.

2) In fact, the sample of two BEV cars for which we have percentage cooling data available shows the cooling drag to be quite high - and higher than many ICE cars.

If there is other data available on the percentage cooling drag of BEVs, I'd love to see it.

[aerohead]

Originally Posted by JulianEdgar

Yes, it seems that some people struggle with the concept of what 'percentage cooling drag' means.

To make what I hope is an obvious point, even if cooling drag stayed the same, as overall Cd of cars drop, the percentage cooling drag will increase.

Most of the other data that is being quoted here is pointless since the discussion is (was?) about percentage cooling drag. And the available data shows that:

1) On current BEVs, percentage cooling drag is nowhere near zero.

2) In fact, the sample of two BEV cars for which we have percentage cooling data available shows the cooling drag to be quite high - and higher than many ICE cars.

If there is other data available on the percentage cooling drag of BEVs, I'd love to see it.

I believe you're attempting to be useful, however the limited data you've provided is limited, contextual, and un-actionable.
If you can't fill in the blanks, then we're at an impasse.