BEV mass and Regeneration efficiency

[Piotrsko]

DIFFERENT class of people

[Vman455]

Originally Posted by aerohead

7) It's quite damning to your hypothesis.

I haven't offered a hypothesis; I've merely quoted graphs from the paper you linked in response to your very odd assertions that don't follow from what the authors actually wrote. If you have data from Volvo that shows they deliberately made an EV heavier in order to improve its efficiency, I'm sure we would all love to see it.

[Isaac Zachary]

A freight train is more efficient than a scooter. That doesn't mean I should buy one so I can commute to work in it and expect to get better fuel mileage than in a scooter.

[freebeard]

The delta will be down in the noise. Is this the best we can do for argumentation?

The weak link in the chain is PV cell efficiency. Exceed the Shockley-Quiesser limit and the equations all stand on their heads.

[redpoint5]

I either don't understand the assertion, or my comment about a system that captures less than 100% of the input energy is less efficient than not spending that energy is correct.

It would be nice to have more than 25% solar>electricity conversion. It would be nice to have a fusion reaction that can harvest the energy in productive ways. Thorium might be a good bridge technology. The future will be amazingly unpredictable.

[freebeard]

It's okay to be correct.

Fusion: science.slashdot.org: 'Burning' Hydrogen Plasma In the World's Largest Laser Sets Fusion Records (livescience.com)

Last year, scientists at the Lawrence Livermore National Laboratory in Northern California announced the record release of 1.3 megajoules of energy for 100 trillionths of a second at the National Ignition Facility (NIF), Live Science reported at the time. In two new research papers, NIF scientists show the achievement was due to the precision engineering of the tiny cavity and fuel capsule at the heart of the world's most powerful laser system, where the fusion took place.

Although the fuel capsule was only about a millimeter (0.04 inch) across, and the fusion reaction lasted only the briefest sliver of time, its output was equal to about 10% of all the energy from sunlight that hits Earth every instant, the researchers reported.

Wow, a 100 trillionths of a second! But today: hardware.slashdot.org: Former Nuclear Regulatory Commission Chair Argues Nuclear Power Isn't a Climate Solution (theverge.com)

"Former heads of nuclear regulatory bodies across Europe and the US put out a statement this week voicing their opposition to nuclear energy as a climate solution," reports The Verge's Justine Calma.
[snip]
Jaczko goes on to note how many of the nuclear plants when he was chairman were supposed to come online but have experienced delays and exceptional cost overruns. Two of the four new design reactors that were licensed when he was chairman, which were supposed to be starting production in 2016 and 2017, were canceled, "and that involved federal indictments for fraud among the heads of the company running that reactor development."

Fraud? Like with Solyndra?

[aerohead]

Originally Posted by Isaac Zachary

Of course, and this has already been brought out, more efficiency doesn't mean better total efficiency or better miles per kWh, etc. A lighter Model 3 will get better miles per kWh even if regen efficiency drops.

A Model 3 also ususally hauls only one person and not much more, and has a limit of 5 (or is it 4?) passengers and some 900lbs total weight of cargo and passengers (although I'm sure you could add more than that). But if you could lighten it and replace that mass with even more passengers and/or cargo, then miles per kWh per passenger or lb of cargo would also increase considerably.

This whole thing reminds me of the BSFC efficiency of an ICE being at around 80% load. But if you drive around constantly at 80% load you'd actually get worse fuel mileage.

1) In the context of the master's thesis, adding mass to the 'small suv' increased its ' total efficiency.'
2) This is predicated upon the New European Driving Cycle ( NEDC ).
3) The explanation requires looking into the reported 'strange behavior...connected to the regenerative braking which is dependent on available wheel power', mentioned by the authors.
4) If you have dynamometer data for the Tesla, on the same driving cycle, at a lower mass, that would make for great supporting evidence on your part. Otherwise, it's an unknown quantity.
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5) Volvo increased the 2015 small suv, from 1572-kg, to 2165-kg, and total efficiency increased 16.8%.
6) It out-accelerates its ICE stablemate
7) It uses 32% of the ICE's energy.
8) It has 3.7X range of the ICE variant.
9) It has 1109 miles range on the ICE's 'pack.'
10) The ICE variant has 57-miles range on the BEV's 'tank.'
11) It has 'Strong regenerative braking.' Duncan Brady, MOTOR TREND
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12) Regenerative breaking efficiency proportionality needs to be factored.
13) Inertia Resistance proportionality needs to be factored.
14) Rolling resistance proportionality needs to be factored.
These are contributing actors in the 'strange'.

[aerostealth]

I was watching TFL Trucks last night and they were testing a Rivian electric truck towing a flat bed trailer with a large pickup truck on the carrier up to the Ike Gap (from Boulder, CO) and back. I won't post a link here because these guys are seriously aero-ignorant but they had a result I found interesting.

Going downgrade and setting their cruise control to 60 mph they only gained a couple kWh and a few miles of range from the regenerative braking. They were very puzzled by this result. The following occurred to me.

1: Regenerative braking energy returns at speed is a function of aerodynamic drag and rolling resistance.

2: A lower drag shape with all the same parameters (frontal area and mass) would allow more regenerative braking energy returns.

3: That it should be possible to map and graph the potential for regenerative braking energy returns as a function of CDA, mass, and speed.

[aerohead]

Originally Posted by Vman455

I haven't offered a hypothesis; I've merely quoted graphs from the paper you linked in response to your very odd assertions that don't follow from what the authors actually wrote. If you have data from Volvo that shows they deliberately made an EV heavier in order to improve its efficiency, I'm sure we would all love to see it.

1) None of the graphs depict the performance of the 'Small SUV' at a different mass. They are not germane.
2) For data, please see #47 (permalink)

[aerohead]

Originally Posted by redpoint5

I either don't understand the assertion, or my comment about a system that captures less than 100% of the input energy is less efficient than not spending that energy is correct.

It would be nice to have more than 25% solar>electricity conversion. It would be nice to have a fusion reaction that can harvest the energy in productive ways. Thorium might be a good bridge technology. The future will be amazingly unpredictable.

In order to understand the 'strange' behavior, requires an understanding of the proportionality between gains from regen, and losses due to inertial and rolling-resistance penalties.
For a delta-10% mass increase, the small suv experiences an 8.1% regen efficiency increase, while only a 1-2% loss to inertia and R-R, for a net gain of approx. 6.6%.
Aerodynamics does not participate.