BEV mass and Regeneration efficiency

[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) Your comment is unproven, so does not qualify as 'theory.'
2) That leaves 'hypothesis' which must stand the rigor of experiment.
3) For about the sixth time, none of the charts in the thesis represent the 'small' SUV at a modified mass.
4) I do have data from Volvo. They added 593-kg to the V40.
5) It's still 'small'.
6) It now has ' Strong regenerative braking.'

[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.

No one's going to understand until they do the math.

[aerohead]

Originally Posted by Isaac Zachary

I think everything should be taken into account, aerodynamics and all.

As stated earlier, just because you get better efficiency in one aspect doesn't mean the overall efficiency will increase or distance per fuel unit spent per person/unit-of-mass will increase either.

• If your vehicle were a solid lead mass, then the amount of energy that could be lost to braking would be much greater than the amount of energy lost to aerodynamic drag. Say the difference is about 90% of inertial energy would be lost during braking and the other 10% to air drag and rolling resistance. If regen is 90% efficient then the total amount of inertial energy that could be recuperated during braking is 81%.
• If your vehicle has the total mass of a feather, then the amount of energy that could be lost to braking is hardly anything and nearly all of it will be lost to aerodynamic drag. If the difference is 50% of your inertial energy is lost to aerodynamic drag and rolling resistance, then it doesn't matter if regen is 100% efficient. You will never recuperate more than the remaining 50%.
• Mind you both vehicles will need to eventually accelerate. The one withe the mass of solid lead will need a whole lot more energy to accelerate. The one mass of a feather will need a whole lot less.
• As aerodynamics and rolling resistance are improved the more all the inertial energy will need a braking effect in order to change it. If a car has 0 aerodynamic drag and 0 rolling resistance, all the inertial energy will have to be either lost or recuperated by some form of braking.
• Something else to take into account is electric motor and controller efficiency curves. A high performance system may be less efficient at low regen currents than higher ones. As a result, it becomes more efficient when there's more mass to slow down. But the same result could be achieved by lowering mass and the performance of the motor and controller. Acceleration would be essencially the same since the power to weight ration would be essencially the same.

Everything was taken into account, including aerodynamics.
After you've run all the numbers, the dust will settle and you'll have a clear look at the situation.

[aerohead]

Originally Posted by redpoint5

Nothing was ever explained. We just get footnote non-responses like we didn't even formulate a question. Totally unreadable and non-sequitur to the question.

I've been waiting all this time for VMAN 455 to return with his mathematics.
Since I'm always wrong, it's obvious that VMAN knows far more than I'll ever aspire to, and has obviously already done all the calculations to verify my 'wrongness.'
Once he returns, it will be a simple matter to just present his quanta, and all will be settled.
He's the lynchpin on this one.
I'm sure he has an explanation for his absence.

[aerohead]

Originally Posted by Isaac Zachary

This is false. There is no Goldilocks mass. I read the thesis from front to back and could not find a thing that says that. There is no optimal inertia. That is my opinion, for whatever that counts.

Did you do all the calculations?
What you're looking for will be in the numbers.
Even Einstein needed a chalkboard to keep square with the world.
It's a Richard Feynman kinda thing.
If you can get to Volvo, jump on a work station, plug in some values, and run the program.
There's a reason why they added 593-kg to the V40 as their 'solution.'
You'll find it in the numbers, hiding in plain view.

[aerohead]

Originally Posted by Isaac Zachary

I examined the testing cycles and did the math and came up with the same conclusion that there is no "goldilocks" mass in a BEV. The evidence I see points to lighter as being more efficient overall, even though it is true that less kinetic energy can be recuperated from regen making it appear to be less efficient when it really isn't.

Do you want to discuss the statistical weighting of the different cycles and how Volvo derived the final aggregate efficiency from all of them?

[redpoint5]

Just realized it was Wednesday! What happened to the Tuesday/Friday experiment?

[aerohead]

Since I have to walk five blocks to and from Copy-Pro, where I 'do' EcoModder.com, the weather has a lot to do with scheduling.
And it's been really fickle lately, making visits a bit random.
I'm driving a friends vehicle and they'd threatened hail and a slight chance of tornados, which scared me off.
I'd rather have their vehicle destroyed at their place, rather than on my watch.

[aerohead]

I just published a table of CURB WEIGHT for Hybrids and BEVs which may help us navigate the 'strange' , small BEV efficiency vs mass and available wheel power talking points.
https://ecomodder.com/forum/showthre...evs-40018.html

[aerohead]

Originally Posted by aerohead

Do you want to discuss the statistical weighting of the different cycles and how Volvo derived the final aggregate efficiency from all of them?

1) The thesis authors foreshadow the existence of a more favorable mass when they relate the 'medium-sized' Volvo S80's mass with respect to more advantageous regenerative braking in relation to the Volvo V40, on page-26.
2) Poor regenerative braking is a criticism related to the V40.
3) Only the 'mass' of the S80 is established towards a 'solution.'
4) That's the set-up.
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5) From there, we better know something about regenerative braking.
6) We better know something about Inertia Resistance.
7) We better know the acceleration rates and average velocities associated with the test cycles.
8) Test results encompass amplitudes, spatial, and temporal distributions which may not resonate with an individual's first order reality experience of automobile dynamics, however they remain the gold-standard for official testing and vehicle certification for legal sales.
9) We better know the boundaries of the official test protocols automotive engineers must frame their research and actions based upon the prescribed results.
10) We better know something about the statistical weighting between the various test cycles and how those weightings will affect the final numerical representation of the specific vehicle when the percentages of all the cycles are combined.
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11) Then, we need to walk outside. We need to leave the clinical sterility and hermetically-sealed environment of academia and the classroom, and take a glance at the real world.
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12) Volvo engineers do not exist within a vacuum.
13) They have a suite of technologies at their disposal to address the concerns raised by EcoModder members.
14) After completing my calculations I experienced deep belly laughs surrounding the 'hair on fire' reactions to the notion of additional mass. You'd think we'd all have to chew off one of our legs, caught is some sort of weight trap of our own making.
The answers are hiding in plain view.
' You can see a lot by looking.' Yogi Barra
PS ' Feed a man a fish and he eats for a day. Teach a man to fish and he eats for a lifetime.'