EV (electric vehicle) News and Discussion

Forums › Transport (cars, bikes and boats) › EV (electric vehicle) News and Discussion

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#2940665 11-Jul-2022 11:53

wellygary: Something like

"But its OK for Warren Buffett to profit from owning around 8% of BYD ??"

If you're going to play the "evil capitalist" card, you might want to do better than Warren Buffet. He has promised to donate over 99% of his wealth.

Perhaps Elon would be a better example, with his union busting and pushing his employee toward Karoshi

Reuters: Warren Buffett donates $4 billion to charity

...Since 2006, the 91-year-old Buffett has donated more than half of his Berkshire shares, with the donations worth about $45.5 billion at the time they were made....

wellygary

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#2940731 11-Jul-2022 15:15

kingdragonfly:
wellygary: Something like

"But its OK for Warren Buffett to profit from owning around 8% of BYD ??"

If you're going to play the "evil capitalist" card, you might want to do better than Warren Buffet. He has promised to donate over 99% of his wealth.

No it wasn't in respect to Mt Buffet being an evil capitalist, - but highlighting the inconsistences of US government restrictions regarding BYD

it was a response to comments to the OP raising US criticism of BYD's practices and why they would never be allowed to be sold in the US,

My comment was a way of saying

"So its OK for the US to ban US consumers to purchase BYD because of their business practices, but its OK for US investors Buffett was the specific, but it was a reference to US investors in general being allowed to invest and make profit from the company....

Batman

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#2940851 11-Jul-2022 22:57

just thought of a way to increase efficiency of EV -

why don't they have another gear that kicks in at say 70km/h (or 80, 90), then when you cruise at 100kph the electric motor is at its most efficient

if you see here the only cars that exceed their EPA range when cruising on the highway at 75 mph (i think that's what it says)

is the only 2 cars with a second gear that kicks in at high speed

Taycan, eTron

https://www.caranddriver.com/shopping-advice/a32603216/ev-range-explained/

is it that hard to have a second gear?

* i wouldn't believe every number is directly comparable with another eg how is a model Y better than model 3 - must be different conditions like wind, temperature, hills etc but just a general trend

* also wondering if someone like Bjorn Nyland can confirm these seemingly magical numbers

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#2940852 11-Jul-2022 23:04

following that i now have a question that nobody seems to know the answer to

how to increase efficiency on climbing hills -

have high power motor so it doesn't work so hard when climbing?

+ high regen abilities when descending

Batman

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#2940854 11-Jul-2022 23:10

when shopping for an EV i don't give a toss about 0-100, WLTP, EPA, other than how efficient it cruises at 100kph on the plains of Canterbury

and how efficient it climbs the crazy hills of Otago in the winter

jonathan18

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#2940855 11-Jul-2022 23:12

@batman has your device lost its shift key and other punctuation related keys

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Linuxluver

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#2940856 11-Jul-2022 23:12

Batman:
following that i now have a question that nobody seems to know the answer to

how to increase efficiency on climbing hills -

have high power motor so it doesn't work so hard when climbing?

+ high regen abilities when descending

If you're not in a hurry, show down. One way to slow down is follow a truck up the hill.

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DS248

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#2940857 11-Jul-2022 23:18

The Audi e-tron GT and Porsche Taycan do have a 2-speed gearbox on the rear axle. And possibly a few other makes/models?

But not generally justified/needed. Added weight and complexity generally out weight any (small) benefit.

Edit: Oh, I see batman added to his post after I started this reply ... and mentioned re the e-tron GT and Taycan

Batman

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#2940864 12-Jul-2022 06:45

Linuxluver:
Batman:

following that i now have a question that nobody seems to know the answer to

how to increase efficiency on climbing hills -

have high power motor so it doesn't work so hard when climbing?

+ high regen abilities when descending

If you're not in a hurry, show down. One way to slow down is follow a truck up the hill.

no idea how that's relevant

my questions is - which consumes less kwh/km climbing an Otago hill at 70-90kph (i don't want to go up a hill at 40kph on the open road to get the most out of the battery - that will just make the trip unbearable for me and the trail of cars following behind. also drafting at 40kph isn't going to help much)

ok back to 70-90kph -

say Ioniq 5 150kW motor, not so aero, 2.5 tonnes fully loaded RWD

Telsa model Y (some people say 250kW motor - i seriously doubt the figure but for argument sake let's say it is) 250kW motor, better aero, 2.3 tonnes loaded

is there efficiency gains if the motor isn't working so hard ...

or is 150kw more than enough to haul 2.5 tonnes - at 70kph? 90kph?

i think it's a relevant question when all my cars cost me between $7000-$40,000 in my life and now you have to fork out $70,000-$120,000. it's a headache

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#2940865 12-Jul-2022 06:47

DS248:

The Audi e-tron GT and Porsche Taycan do have a 2-speed gearbox on the rear axle. And possibly a few other makes/models?

But not generally justified/needed. Added weight and complexity generally out weight any (small) benefit.

from the charts it's not a "small" benefit!

compare Taycan vs Kona / Model 3

(if the chart is correct - the article does say Model 3 was tested in the cold, doesn't say anything about other cars)

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#2940905 12-Jul-2022 09:13

As a general rule, under all conditions, slower is more efficient. Drag is proportional to the cube of velocity; power is (sort of, it isn't a straight line for a real motor) proportional to current. If you want to double your speed you will need ~8x the power, so ~8x the current. But resistive loss in the power train is proportional to the square of the current so at double the speed you waste on the order of 64x as much energy due to resistance, directly impacting your range. EDIT: of course I forgot to add that you get there in half the time, so the total loss is "only" 32x as much.

Gears don't really change it that much with an electric motor which has a much wider range of speed where power is approximately linear. So as others have said - that's why most EVs don't have a multi-speed transmission. The benefits just don't outweigh the extra complexity and weight. Combustion engines require complex transmissions because of their narrow speed range.

In any case ... if you try driving at 75mph in NZ, it won't be the range of the car that crimps your style.

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#2940914 12-Jul-2022 09:48

Batman:

Linuxluver:

If you're not in a hurry, show down. One way to slow down is follow a truck up the hill.

no idea how that's relevant

It's the only thing that's relevant. You're attempting to beat physics.

Going up a hill will require you to spend energy to gain gravitational potential energy, and to beat the friction/drag force from your tyres and aerodynamics.

Nothing you can do about the hill itself, so the only way to use less energy is to minimise that drag/friction, by slowing down (as Salty has pointed out).

Different cars will have different CdA products which helps with the drag, better tyres will help drop your rolling resistance, and having a bigger drive train will reduce losses that result from the high power draw, but they all pale in comparison to just driving slower. By orders of magnitude.

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#2941112 12-Jul-2022 12:52

ok so more kw/hp motor doesn't help. cheers

one day i'm going to compare the EV6 RWD and the Model Y RWD and do the hills at different speeds and see what happens ...

mkissin

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#2941114 12-Jul-2022 13:00

Batman:

ok so more kw/hp motor doesn't help. cheers

one day i'm going to compare the EV6 RWD and the Model Y RWD and do the hills at different speeds and see what happens ...

That would be super interesting if you were able to collect useful data, so I hope you do!

Interpret the data would require you having the CdA for each car, which manufacturers almost never give out. This is different to the just the Cd (drag coefficient) number, which they do often spout in marketing material, but which is largely meaningless without the A bit (the frontal area).

You'd also want the rolling resistance of the tyres, and so on and so forth. Basically, you need a wind tunnel and a dyno.

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#2941116 12-Jul-2022 13:07

Apologies if already posted, but I found this short video of Rory Reid’s on the downsides of EV battery swapping interesting viewing.

A few weeks back I watched a fairly fawning video of another UK YT car person visiting the Neo battery swapping station in Norway, who seemed quite taken with the idea - Reid’s critique of the approach seems far more realistic.

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