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Old 05-30-2024, 11:57 AM   #612 (permalink)
aerohead
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extreme scenario

Quote:
Originally Posted by redpoint5 View Post
If we disagree, it's probably about the definition of "significant".

I'll arbitrarily pick 3% as my threshold for what constitutes a significant difference with driving technique alone, and confine the dataset to the middle 80% of the normal bell-curve distribution, tossing out those who drive like the gas and brake are on/off switches, and likewise those who only drive steady speed on the freeway, and therefore technique doesn't play a factor.



If you're thinking about it, might as well speculate.



Even full self-driving fails to do this, ignoring the red light ahead and accelerating towards it despite sensing the red light.

It matters much less when you can get 80% of that back, though.



What percent difference do you speculate driving habits (same cruising speed and HVAC use) alone account for?




I have not, which is why I suggest the test, especially with a forum member so relatively nearby (I'll say hi to freebeard while I'm there).

Having difficulty measuring to 1% would only matter if that's how insignificant the difference is, which would reinforce my point.



I've only twice brought the Prius plug-in from zero EV range, back to full using regen (only ~3 kWh), and that was one of the instances. Ended up wasting a good deal of energy downshifting since once the battery was full, it was no longer slowing the vehicle.



My spidey senses tell me it would be a very extreme scenario where 40 of the 250 mile range is provided by regen. Now that I've made that assertion, I'll see if math tends to support it...

According to Fueleconomy.gov, the Bolt uses 28 kWh per 100 miles.

40 regen miles / 100 miles = 0.4
0.4 * 28 kWh = 11.2 kWh gained from regen

The way to think about that is to imagine 11.2 kW (15 horsepower) being regenerated for 1 full hour. Of course, slowing isn't just a one time event, but spread out over the full trip length, and capable of up to 70 kW (94 horsepower).

In a hypothetical scenario where one could achieve full regen for 1 continuous regen event that supplied the full 11.2 kWh of charge back to the battery, it would take nearly 10 minutes.

It seems unreasonable to me that the Bolt could, on average, gain 40 miles of range by regen. My guess would be closer to 4 miles of range, on average. Some trips would be zero, like steady freeway cruising, and others would be more than 4, like stop and go traffic.
The quanta he reported was constrained by five EPA test protocols legally mandated to be used for new car certification in the USA.
He wasn't given any special latitude.
And the premise of EPA testing is that, anyone 'driving' a BOLT on the same dyno maps 'WILL' come up with the identical 40-miles that GM experienced.
The penalties for misrepresenting car performance are typically too great for an automaker to risk it.
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