Category: Analysis

Anything that I have tested empirically, or explain with detailed calculations, or just generally bother to get all the facts straight.

Post #1926: A Prius driver takes a pass on Chevy Bolt “one-pedal driving”.

 

Do electric vehicles (EVs) get rear-ended more often than conventional cars do?

They certainly should.

That’s my conclusion after trying out the “one-pedal driving” mode on my new (used) 2020 Chevy Bolt.   And working through the logical consequences of it.

The practical bottom line of this post is that you should think twice before you tailgate an EV in traffic.  Because the chances are good that they can stop a whole lot faster than you can.   And may give you less warning when they do.

Not convinced?  Keep reading the parts in red, below.

Words do not do it justice: An accurate description of one-pedal driving mode.

Source:  Yeah, I know it’s a front-wheel-drive car.  The Gencraft AI doesn’t, though.  Almost all pictures here are courtesy of Gencraft.

Here’s your typical bland one-sentence description of one-pedal driving mode:  “With one-pedal driving, the car has enhanced regenerative braking, and will begin to slow as soon as you ease up on the gas (accelerator).”

Before I bought a Bolt, my reaction to that was, big deal.  Almost all modern cars do that, to a degree.  Anything with an automatic transmission slows when you take your foot off the gas.  All hybrids use regenerative braking, that is, they slow down by generating and storing electricity, reserving the friction brakes (pads pressing on rotors) as a last resort.

Some EVs can now do it more?  Whoop-te-doo.

Now that I own a Bolt, I know that description is missing a key word:  Abruptly.  Or, rapidly. Or, with great force.  Take your pick.

Taking your foot off the gas in “one-pedal” mode is nothing like taking your foot off the gas in a normal or hybrid car.  You don’t coast, at all.  You stop, pronto.  Not quite a wheels-locked panic stop.  But far faster than I normally stop, and far faster than anyone would reasonably expect me to stop in traffic.  In the Bolt, in one-pedal model, take your foot off the accelerator and you pull a few tenths of a G worth of deceleration.  Enough to pull you forward in your seat.  Enough that there’s no way I would engage that mode in snowy or icy roads.  Enough that I’d think hard about it before I turned one-pedal driving on in a driving rain.

Enough, already.  You get the point.  Here’s a more accurate description of one-pedal driving mode:

The act of lifting up on the accelerator, in one-pedal driving mode, is equivalent to pushing the brake pedal.  Hard.  Your (lack of) accelerator pedal is your brake pedal.  It’s not 100% as much force as you can get, if you actually do mash down the brakes.  But it’s an appreciable fraction of it.

You may again think, so what?  So you can, in effect, actuate the brakes, without hitting the brake pedal.  What’s the big deal?

Keep reading.

Brake lights?  We don’t need no stinkin’ brake lights.

But wait, it gets better.

Prior to mid-2023, some EVs would do that — stop fairly abruptly, in one-pedal mode — without turning on the brake lights.  And no, I’m not kidding about that.  (Reference).

The worst of those were fixed via software update, so now, all EVs on U.S. roads will now show brake lights, at some point, during some level of deceleration, in one-pedal driving mode.

As an afterthought.  Does that make you feel better about it?

But even now, an EV manufacturer’s decision on when, exactly, to show brake lights, during rapid braking in one-pedal driving mode, is entirely voluntary, and entirely up to the manufacturer, here in the U.S.A.  And for all of them, those lights turn on after the car has started slowing down.

Oddly enough, if you see this brought up on-line, you’ll see nothing but apologists for it.  Ah, cars have always had ways of slowing down without showing brake lights.  Let off the gas, in an automatic-transmission car.  Downshift in a manual.  Or, if you’re a jerk, hit the parking brake to stop, to fake out the folks behind you.

But those events were either mild in nature (automatic transmission), or rare and mild (nobody in the U.S. drives a manual these days, and nobody in the last 50 years has been dumb enough to wear out their clutch rather than brake pads by routinely slowing the car by downshifting).  Or required outright malice, like using a hand brake to stop.

Now, by contrast, you’re putting out a whole fleet of cars, for Joe and Jane Driver, all of which are designed to be driven without touching the brakes.  Designed to allow for substantial rates of deceleration without using the actual brake pedal.  And for which the decision about whether, or when, to turn on the brake lights at some point during that one-pedal deceleration, is an option for the manufacturer to decide. 

Let me offer a clear contrast to what you are used to, in a traditional gas car.  There, the brake lights are designed to light the instant you rest your foot on the brake pedal.  Brake lights are actuated by a switch that typically sits directly above the metal bar holding the brake pedal.  That switch has a fine adjustment on it.  You literally fine-tune-it so that the tiniest movement of the brake pedal closes the switch.  Even the lightest possible braking pressure will turn on your brake lights.  Properly adjusted, you literally turn on the brake lights before the brake pads make contact with the rotors.

So we now have a mixed fleet of cars on the road.  For 99% of them, the brake lights illuminate as soon as the driver puts on the brakes.  For the remaining 1%, the lights may come on at some point, after the driver has “put on the brakes”, assuming the rate of deceleration exceeds the manufacturer-specified threshold.

Yeah, what could possibly go wrong with that?

Braking distance versus stopping distance.

Definitions:  Both terms apply to panic stops.  Braking distance is how far your car travels, from the moment that you’ve firmly stomped on the brakes, until you reach a complete stop.  Stopping distance, by contrast, is that, plus the distance you travel during your “reaction time”, that is, the time it takes to say “oh shit”, move your foot off the gas, and hit the brakes.

Honking the horn is optional, but highly recommended here in Northern Virginia.

Now for just a bit of math.

1:  It takes about three-quarters of a second to lift your foot off the gas, and put it on the brake, in a panic stop.  That’s in addition to the initial reaction time — the time it takes you to realize you need to stop quickly.  (Estimates vary, that’s my reading of the literature on the subject.)

2:  At 30 miles per hour, in that amount of time, a car moves about two car lengths.  (Calculated as (30 MPH *5280 FT/MI *(0.75/(60*60) HOURS) = ) 33 feet.

3:  EVs in one-pedal driving mode can initiate an abrupt stop without moving their foot to the brake pedal.

My takeaway from all that is that EVs in one-pedal driving mode should be able to panic-stop somewhere around a couple of car lengths shorter than traditional cars.  That’s not due to better brakes, or better drivers.  That occurs because they begin to brake rapidly before they even move their foot to the brake pedal.

Yeah, what could possibly go wrong with that?

Summary

Shorter stopping distance is just dandy if you’re driving an EV in one-pedal mode.  But maybe isn’t such a plus for the person in a standard vehicle, tailgating an EV in one-pedal mode.

If you are in traffic, behind an EV in one-pedal mode, and the EV in front of you makes a panic stop, you need to be aware that, compared to a conventional car or hybrid:

1: That EV is inherently capable of stopping faster.

2: That EV will give you less time to realize it is stopping.

And nothing about that car will give you the faintest hint that those two factors are in play.

You’ve been warned.

Background:  Regenerative braking the Toyota way, or why Bolt one-pedal mode does me more harm than good.

We changed the brake pads on my wife’s 2005 Toyota Prius sometime around 140,000 miles.  Up to that point, the brakes hadn’t needed any attention.

The crazy thing is, that’s not even brag-worthy.  Going 100K miles between brake jobs is normal for any car with regenerative braking.

The Prius has regenerative braking.  To the greatest extent possible, the car slows down by turning itself into an electric generator.  It converts the forward momentum of the car to electricity, which then charges the traction battery.  Cars with regenerative braking routinely go 100,000 miles between brake jobs.  So says the U.S. DOE.

No material efficiency gains — for me.

The reason for the low brake wear in a Prius is that almost all the braking energy is done electrically.  In an ideal gentle stop, the friction brakes only kick in below about 5 MPH.  (If your rotors have surface rust, and your windows are open, you can hear that happen until you knock the rust off the rotors.)

In an idealized stop from 30 MPH to zero, you can easily calculate the fraction of braking “power dissipation” accounted for by electrical generation versus friction brakes.  Kinetic energy goes as the square of the speed, so, in a hypothetical gentle stop from 30 MPH to 0 MPH, where the friction brakes only handle the part below 5 MPH, the fraction of braking energy is:

Friction fraction of braking energy = 5-squared/30-squared = 25/900 = ~3%

Electrical Fraction of braking energy = 1 – friction fraction = 97%.

In other words, with a reasonably gentle stop, in typical suburban traffic, regenerative braking (Toyota-style) converts about 97% of the car’s forward momentum to electricity.  You don’t get to keep all of that, because there are losses in the electric motor/generators, the wires and charging electronics, and in charging the battery.  Maybe you keep 80% of that, or so.

One rationale offered for EV one-pedal driving is that it improves efficiency by recapturing more of the potentially available energy from braking the car.  That’s because you can literally bring the car to a full stop, and so, in theory, capture 100% of the car’s forward momentum and convert it to electricity.  Of which, again, you might be able to keep and use maybe 80%, after all the relevant losses are factored in.

And that’s the main reason that Bolt one-pedal driving does more-or-less nothing for my driving efficiency.  Because, despite what you may read, the Bolt’s regenerative braking does more-or-less the exact same thing as the Prius, during moderate stops.  In normal (not one-pedal) driving, when I take my foot off the gas, the car begins to recapture energy through regeneration.  And when I push gently on the brake, it begins to capture even more energy through regeneration.  Just like a Prius.  (All you have to do is look at the dashboard, as you brake, to see that this is true.)  And in a normal, gentle stop, with rusty rotors, you can hear the Bolt friction brakes engage at about the same speed as the Prius — about 5 MPH.

I guess if you drive like a bat out of hell, regenerative braking can improve your efficiency somewhat.  Plausibly, those who routinely make quick stops can benefit from converting more of the stop to electricity, before the friction brakes kick in.

But my driving habits were formed during the Arab Oil Embargoes/energy crises of the 1970s.  And I’m cheap, to boot.  So I try to avoid rapid stops.

My gut reaction, from reading about this, is that the real fan-boys for one-pedal driving are, in fact, those who want to drive like a bat out of hell.  They like it for the “sporty” feel, and how it lets them zip around all that much faster.  Which, to me, makes the whole “efficiency” argument kind of silly.  If you drive that way, clearly efficiency isn’t your goal.  You’d get more miles per KWH by not trying to drive the Bolt like a sports car.

So, from my perspective, as far as efficiency goes, one-pedal driving provides a marginal improvement in efficiency, for those with habitually inefficient driving styles.  Turning that around, if you’re a laid-back driver by nature, you ain’t going to get much additional efficiency out of one-pedal driving, beyond what you get from regenerative braking in “normal” driving mode.

Extras for experts, 1:  There is one weird final twist on this, in that, in a hybrid, regenerative braking doesn’t much matter.  It might typically add just 2% to the vehicle’s overall efficiency.  That’s from a combination of factors.  First, even with the efficient Atkinson-cycle engine of a Prius, you start off by wasting 60% of the energy in the gasoline.  Second, with relatively small electric motor/generators, and most importantly a relatively small battery, the amount of regenerative braking force — the amount of current you can safely generate and squeeze into the battery, without damaging anything — is highly limited.   So for the U.S. EPA drive cycle, with its extended periods of fast stop-and-go driving, you tend to show only a modest amount of energy recapture, as a fraction of the total energy used by the vehicle.

In an EV, by contrast, regenerative braking is a much higher contributor to overall vehicle efficiency, as the Federal government measures it.  First, unlike a hybrid, all the inefficiency in converting fossil fuels to electricity is “off the books”, so to speak.  That occurs at your local utility, not in your car.  The calculation of overall car efficiency starts with charging it, so as a whole the vehicle appears to have vastly less total wasted energy, than a hybrid does.  Second, with large motors and much larger battery, you can safely put more current into the battery.  Thus, in a hard stop, an EV can likely capture more of the energy than an hybrid can, prior to applying the friction brakes.

Old dog, new trick — look ma, no brakes!

The first thing about Toyota-style regenerative braking is that it’s absolutely seamless.  In the best case, you wouldn’t even guess that the car had this feature.  Only if you listen very closely, and brake very slowly, can you discern the point at which the friction brakes are engaged.

The second thing about Toyota-style regenerative braking is that hybrids with regenerative braking behave exactly the same as any non-hybrid car with automatic transmission.  Take your foot off the gas, and the car begins to slow just a little bit, just like any other automatic-transmission car (then) on the road.  The harder you push on the brake pedal, the more braking force you get.

Regeneration in the Bolt, by contrast, feels nothing like a normal car in this regard.  It is far more aggressive, even in normal (not one-pedal) mode.  Take your foot off the gas in a Bolt, and you slow much faster than you would in a standard car with automatic transmission, or in a typical hybrid.  I have already had to break myself of the long-learned habit of lifting my foot from the gas when I see a red light ahead.  On the roads around here, If I were to do that in a Bolt, I’d come to a dead stop long before I make it to the light.

But I can live with that.  I lift my foot, eyeball the dash, and look for the something close to zero KW going into or out the battery.  It’s hardly a life-changing difference in driving technique.  Not after I had to re-learn driving for the Prius Prime, and its preference for constant-power (instead of constant-force) acceleration (Post #1618:  There ain’t no disputin’ Sir Isaac Newton).

But switching to one-pedal driving has one potentially life-changing difference:  You may lose the instinct to put your foot on the brake.  If you never need to panic stop, you can literally drive the car in one-pedal mode and never touch the brake.   (Some one-pedal fans brag about doing exactly that.)

So do I, as a 65-year-old guy, now want to train myself to drive in one-pedal mode?  This, when the approach to driving is so different from our other car (a Prius).  And this, where driving in this new style means basically to ignore the brake pedal.

Short answer, no.  Sooner or later, in NoVA traffic, I’m going to have to do a panic stop.  And when that happens, that panic stop happens on instinct.  It took me close to 20 years to get used to ABS, and to lose the instinct to release the brakes in response to a skid, and just keep my foot mashed to the floor.  I really, really don’t want to lose the instinct that tells me to hit the brakes in an emergency-stop situation.

So, it’s not that I couldn’t learn this new trick.  It’s that I probably shouldn’t.  Not with driving two different cars.  And not with my recent entry into geezerhood.  Better to leave sleeping dogs lie.

The Prius Gene

This is a true story.  We bought our first Prius in 2005.  The same week that we bought ours, hundreds of miles away, with no communication between us, one of my brothers also bought his first Prius.

We’re now a two-Prius family.  I think my brother and his wife have been a three-Prius family, with one going off to Prius heaven as a result of a freak highway accident.

My brother says the exact same thing about his Prius, as I say about ours:  It pushes all my buttons, in just the right way.  From the super-smooth acceleration with no gear shifts, to the dashboard feedback on mileage, pretty much everything about the car says “relax, chill, enjoy the drive”.

Maybe we both like that because that’s pretty much the way my dad drove.  Maybe we inherited the genes that give us that bent.  In any case, it seems to run in the family.

It takes some work to drive a Bolt as if you were puttering along in a Prius.  But for whatever reason, by golly, that’s how I choose to drive it.

So, no one-pedal mode for me.  It’s insufficiently Prius-like.

Post #1923: Gym use during our normal winter peak of COVID-19 cases.

 

My wife masked up at the gym yesterday.  Not at random — no matter how much fun that might have been — but because several friends of hers have gotten COVID recently.

Gyms are known to be risky places for COVID transmission.  That was clear from epidemiological analysis done during the pandemic.  And that’s unsurprising, given that COVID spreads by airborne transmission, and breathing hard is part of cardio exercise.

This means it’s time to get back in touch with the most recent statistics on COVID cases in Virginia.  So, without putting in a lot of effort, I’m going to get a snapshot of reported COVID cases in Virginia.

Briefly:  This is just the new normal.  We seem to be on track for our regular wintertime peak in COVID-19 cases.  Winter ’23-’24 looks like it’ll be about the same as winter ’22-’23.  Whatever precautions you thought were appropriate at this time last year are probably appropriate now.

Our regular winter COVID 19 peak

The first thing I note is that we’re on track for what has become our normal winter peak in severe COVID-19 cases.  That, based on hospital admissions for COVID, from the CDC, for the past four winters, as marked:

Source:  CDC COVID data tracker.  Annotations are mine.

Separately, Virginia still tracks total lab-reported cases.  These are individuals who were diagnosed by DNA testing done in labs, not by “quick” testing typically done in the home.  Again, we seem to be on track for an early-January peak in total new reported cases.  Same as for the past three years.

 

Source for both of the above, less my annotations:  Virginia Department of Health.

The upshot is that new cases, and new hospitalizations, are roughly where they were this time last year.

Nor has COVID itself gotten any more virulent compared to last year.  The most recent prevalent strain of COVID (JN.1) appears neither more nor less virulent than any of the other recent strains (per CDC). Nothing has come along since Omicron that has motivated the Powers that Be to use up another Greek letter to name a significantly new strain.  So JN.1 is just the worthy descendent of Omicron.

So — same timing as last year, roughly the same incidence as last year, roughly the same virulence as last year. Whatever precautions you were comfortable taking last year at this time, well, you should feel comfortable taking them again, now.  Because this ought to be the peak of new cases, or nearly, if this year is like the past three.

To be clear, new cases are appearing in all age groups.  This, from Virginia, for the past 13 weeks:

Source:  Virginia Department of Health.

But serious cases overwhelmingly occur among the elderly.  Below are the rates of hospitalization, by age group, from mid-December 2023, from the US CDC.

I don’t want to make light of this.  The same CDC data source shows that COVID-19 cases currently occupy about 5% of all staffed hospital inpatient beds in the Virginia.  And COVID-19 deaths account for about 5% of all current deaths in Virginia.

So COVID-19 is still serious and costly business.

But so is most of U.S. health care.  And my only real point is that it’s not hugely different from last year at this time.  The current increase in cases, mid-winter, is just the new normal.

The new normal, and a little calculation.

Let me quickly redo my “risk of exposure” calculation for my trips to the gym, based on an incidence of roughly 20 new cases per 100,000 per day, here in Virginia.  As I have done in the past, to arrive at a guess as to how many people are walking around in an infectious state, I multiply the raw incidence by nine, to account for a) under-reporting of new cases and b) the average number of days that an infected person walks around being infectious to others.  So I’m starting with an estimate that about 180 persons per 100,000 (0.18%) are currently walking around in Virginia, actively infectious with COVID.

With 25 people in the cardio room at the gym, the likelihood that:

  • Any one person is infectious:   0.0018
  • Any one person is NOT infectious: 1 – 0.0018 = 0.9982
  • All 25 people are NOT infectious:  (0.9982)^25 = 0.9559 ~=0.96
  • At least one person IS infectious = 1 – 0.96 = 0.04 = 4%

Being in the same room as an actively infectious person is not the same as getting infected.  That said, that’s a non-negligible risk.

I’d say my wife was entirely justified in masking up at the gym (along with several others).  Based on evidence, not anecdotes.

And I was plausibly justified in not doing that.  Based on ignorance.

But now that I know what the odds are, yeah, if the rates don’t peak soon, I’ll probably resume wearing a ventilated 3M N95 to the gym.  At least for now.

Avoidable risks don’t change just because nobody’s taking them seriously.

Post #1922: Venn Diagram of Used Chevrolet Bolt Search.

A:   Not a salt-belt car.  Turns out, the majority of used Bolts for sale here in the DC area were sold new in the Northern U.S.  The cold isn’t the issue.  Multiple winters of driving on heavily-salted roads is the issue.  I don’t want a salt-belt car.

B:  No accidents, no obvious damage, no ludicrously excessive mileage.  I think the rationale there goes without saying.

C:  Dealer is not obviously a shithead.  And here, I’m not talking about the comments on Yelp (because those are always negative).  I’m just looking for a dealer where the majority of comments, on some mainstream site (e.g., cars.com), do not start off with some variation on “If I could give them negative stars … “.

As I sift through what’s listed within 25 miles of me, on Edmunds.com, this is how it shakes out.  This is what mathematicians call an over-determined system of equations.  Nothing satisfies all the constraints.  Or, the intersection of the areas is a null set.  Say it any way you like.

If I continue to pursue this, something’s going to have to give. At this point, I’m leaning toward buying a salt-belt refugee, from a seemingly decent dealer.  I mean, seriously, how much damage could three winters on salted roads cause?  Guess I may find out.

To be continued.

For the literal-minded of you, no, that’s not a proper Venn diagram of the situation. Some circles should overlap others, somewhere.  But it doesn’t look like a surprised face then, does it?  With the choice between literal mathematical correctness on a throw-away diagram, and some possible humor value, I went with attempted humor.  So sue me.  This is really more an expression of frustration over what ought to be a straightforward search for a commodity product.  But isn’t.

Post #1919: Salted Leafs and Bolts, an unexpected twist in my search for a used EV.

 

I’m in the process of narrowing down the used EVs I want to look at.

I just got a rude, but entirely logical, surprise.  It turns out that a lot of the late-model used EVs for sale in this area are salt-belt refugees.  That is, they were sold new in northern states, where they salt the roads heavily all winter long.  But were shipped south for re-sale as used vehicles.

The story.

Based on the ratings of car dealers on-line, I’ve focused on a couple of independent used car dealers in my area.  (FWIW, Kingstowne and Eastern’s Sterling).  I think maybe the phrase in italics is key, because these aren’t new-car dealers accepting trade-ins.  These are used-car dealers.

As I was doing my on-line due diligence, seeing what I can see about these cars by VIN, I happened to notice that one car I’m interested in — a 2021 low-mileage Bolt — was originally sold in Michigan.

Hmm.  Funny that this car ended up in Virginia.  But people move, and so on.  And yet …

I tracked down the original state of sale for the other two I’m focused on — 2020 and later, relatively low mileage.  Those were originally sold in Upstate New York, and Vermont.

One salt-belt car might be by chance.  But every car I’m looking at?  Highly unlikely that’s a coincidence.

I can guess what’s driving this.

EVs lose a lot of range in cold weather.  That’s a fact.  None of these cars has an efficient (heat-pump) heating system.   Also a fact.

I have to guess that:

  1. You have a lot more dissatisfied owners in cold-climate states.
  2. You get a much better resale price on these vehicles, in warm-climate states.
  3. So there’s a steady trade in shipping used EVs south for resale.

The issue isn’t that these were driven in the cold.  The battery management systems on these cars will all prevent the owners from damaging the batteries permanently by (e.g.) charging when the batteries are below 32F.

The issue is that all of these cars are salt-belt refugees.  That is, they were driven in the states where roads are heavily salted, for a significant fraction of the year.

After a few months of watching YouTube auto mechanics in salt-belt states (Watch Wes Work, from Illinois, and South Main Auto Channel, from upstate New York), one thing that comes through loud and clear is that salt is incredibly destructive.  Among the things I learned from those videos is the term “rust jacking”, which is when the accumulation of rust literally bends and breaks metal parts of the car.  Never seen that around here, and I’ve owned a lot of crappy old cars.

And so, once again, I need to stop and cool my jets, as I give this a re-think.  And look at what’s available as a used vehicle, from local new-car dealers.

Post #1918: Falling Leafs, fallen Bolts: The trend in used EV prices in my area.

 

I don’t drive much.  I haven’t had a car for a couple of years now, and have gotten along  by borrowing my wife’s car, when convenient.

I’d like to get my hands on a nice, used EV.   That’s a good choice, given that I’m going to use this for a grocery-getter and little else.

Depending on the price, of course.  And I’m clearly in no hurry to buy one.

Back in July I looked at my local market for used EVs and narrowed my best option down to a 2018 or later Nissan Leaf.  That’s laid out in a series of posts around Post #1837, and the posts just prior to that.  The year cutoff was due to a change in the Leaf battery chemistry that year, to a much more stable (long-lived) battery.

I have been checking back occasionally ever since.

And I’ve been reading articles suggesting a steep decline in the price of used EVs.  I see talk about price declines on order of 30% per year.   This is almost always attributed to the fact that most used EVs are Teslas, and Tesla made some steep price cuts to their models this past year.

In other words, a falling tide sinks all boats.  Those Tesla price cuts are rippling through the entire used EV market.

But in addition, Chevy cut the price on the Bolt last year.  Both to spur sales, and maybe because the Bolt was plagued by a significant recall due to battery fire issues in a handful of vehicles.  Chevy claims that’s taken care of, but they ended up replacing the batteries in tens of thousands of cars.

In any case, when I went back to re-assess my local market for used EVs, it sure did seem like prices were down.  So I did my best apples-to-apples comparison between what I looked at back in August, and now.  As shown above.

By my estimate, asking prices for a used late-model Nissan Leaf fell 14% in the last five months of 2023.  Or … on-order-of a 30%/year rate of decline. 

More interestingly, I can now get a used Chevy Bolt for about the same price as a used Nissan Leaf.  This is a change from the prior analysis, where my back-of-the-envelope on a Bolt of this vintage, five months ago, put the average asking price at $21,000.

But now, consistent with the decline in the Leaf price, there’s been an even steeper decline in the Bolt price.

Objectively, the Bolt looks like a lot more utility for the money.

  • The Bolt has about 90 more miles of range than the leaf (about 250, versus about 160 for the base Leaf)
  • It uses a standard (J1772) plug, instead of the soon-to-be-obsolete CHADMO plug on the Leaf.
  • It has active battery temperature management, compared to the Leaf’s passively air-cooled battery.

The sole drawback from my perspective is that the Bolt looks like a tiny little car, where the Leaf does not.  To me.  They have roughly the same interior volume, and the Bolt actually has a higher curb weight than the base Leaf.  But the Bolt is shorter by about a foot-and-a-half.  Just enough that I notice how small it is, compared to (say) the 2021 Prius that my wife drives.

For either car, if you had little enough income in the year of purchase, Uncle Sugar will give you a $4K tax rebate for purchasing that used US-made EV.  (Yep, for purchasing a used US-made EV.  Part of the Biden Administration’s buy-American industrial policy intersecting with its global warming initiatives. So, thanks, Joe Biden. I guess.)

Rumor has it that the big drop in the Bolt price is due to Chevy rehabbing and re-selling a lot of those recalled vehicles.  I’m not sure how much that is true.  What I am sure is that the Bolt looks like a pretty good option, if you trust Chevy to have fixed that rare battery issue.  If you pick and choose, you can plausibly pick up a three- or four-year-old car, with about 10K miles on it, for a net $13K or so.

This, where the only expensive component — the battery — comes with a mandatory eight-year/100,000 mile manufacturer’s warranty. Which should, in theory, take a whole lot of the risk out of this used-car transaction.  Roughly speaking, you pretty much have to get at least five years of driving out of the car, or the manufacturer (not the seller!) has to replace your battery.

As used cars go, that seems like a pretty decent deal, regardless of the fuel source.  The fact that this is the low-carbon alternative is almost gravy, at this point.   To me, based on what I’ve been looking at, this now looks like it’s just a pretty good deal on a used car.  Period.

I have to confess that the first and last Chevrolet product that I ever bought was a Chevy Vega.  It was a traumatizing experience in many regards, as those of you familiar with the history of the Chevy Vega will understand.

I guess, going on 40 years later, maybe I can find it in my heart to forgive, and give Chevy another try.

Post #1911: LED Christmas light life expectancy.

 

This post goes way over the TL;DR line.  If you want to get to my summary on buying LED Christmas lights that will last a while, go to the Conclusions section in red, below.

Source:  Except where noted, images in this post are from the Gencraft.com AI with a prompt of “Christmas lights”.

Intro:  The ghost of Christmas lights past.

My parents had the same sets of Christmas tree lights for my entire childhood.  And then some, given that I was the youngest of four children.

I, by contrast, am getting ready to toss (recycle) yet another couple of strings of dead Christmas lights.   In this case, some elderly miniature incandescent light strings that started off the season dead.  Again.  And for which I am finally throwing in the towel. Continue reading Post #1911: LED Christmas light life expectancy.

Post #1909: Never eat at a place called Mom’s.

 

And don’t trust Grandma.  Or the Amish.

This evening my wife strongly hinted that I ought to replace the broken jar of black raspberry jam that was the focus on my just-prior post.  No fool I, I immediately got on-task.

So this is my second attempt to buy her some black raspberry jam, as a Christmas present.

This time I looked at every black raspberry jam offered on Amazon.

After my nth jar of jam, I came to a firm conclusion:

The folksier the name, the lousier the product.

Grandma’s Old-Fashioned Amish® homemade black raspberry jam.

You typically can’t find black raspberry jam at the grocery store.  The berries themselves are small and fragile.  That makes it an expensive crop to grow, per pound, compared to other berries.  As a result, black raspberry jam is typically priced at several multiples of (e.g.) strawberry jam.  And I guess that’s a non-starter for the grocery store shelf.  Which is why I’m ordering it off Amazon.

But not all jams are created equal.  They are some combination of fruit, sugar, water, pectin, and maybe an acidifier like lemon juice.  And sometimes other stuff.  Some are primarily fruit, with just enough of the other ingredients to sweeten it, hold it together, and keep it from spoiling.  Others are closer to berry-flavor sugar.

All I wanted, in my first cut, was to restrict this to jams for which black raspberries were the first-listed ingredient.  Ideally, I’d like jams where they were the majority ingredient, but unlike some European labeling, U.S. labeling law does not reveal percentages.  The U.S. simply requires that ingredients be listed in order of weight.  So I’ll settle for jams where sugar and water are listed after the berries.

(That’s assuming I could actually find the ingredients listed somewhere on-line.  It was surprisingly common to find jams listed on Amazon, but never showing the legally-required list of ingredients.)

So here’s a little quiz.  Based on the look of the jar, which of these do you think have the berries as the first-listed ingredient?

Source:  Amazon.

The trick is to toss out anything that says “Grandma”, “Amish”, or “Homemade/Homestyle”. Those are all the lower-quality jams where sugar outweighs berries.

We all know that none of these were actually made by Grandma, at home.  (Then sold in huge quantity on Amazon.)  The fact that the makers felt compelled to call them “Grandma’s Homemade” should have been a clue that they were compensating for something.

But as for the Amish, this is not to imply that the Amish make bad jam.  The issue is that “Amish” isn’t trademarked.  Anybody can make anything, anywhere, and label it “Amish.”  In fact, the last product (Kauffman’s) is made in Bird-in-Hand, PA, and so plausibly actually is Amish- (or maybe Mennonite-) made.  It just doesn’t try to sell the product based on that association.

Anyway, the ones with black raspberries as the first-listed ingredient are below.  Only for the two French ones (Chantaine, St. Dalfour — really, the same company) can you tell that black raspberries make up 51 percent of what’s in the jar.  For the rest, all you know is that there’s more black raspberry than there is of any one other ingredient.

Conclusion

Never eat at a place called mom’s.  And never buy jam made by Grandma.

Post #1894A: A minor technical followup on the NY Times/Siena poll results

I’m still looking for loopholes.  Hence, three remaining questions:

  • How was the sample selected, and in particular, did it require a successful match from voter record to cell phone record?
  • What was the overall response rate?
  • How well does this benchmark with the actual 2020 results?

L2 file?

After reading the end-notes on the detailed tabulations of the NY Times/Siena College poll, my main remaining question is:  What is the L2 file?

Survey respondents were chosen (in a sophisticated-but-neutral way) from persons on the L2 file.  That file is the “universe of observations” for the survey.

Based on the U. Penn description, the L2 file contains public information on about 200M persons who recently voted.  And, about 95 million cell phone numbers.

The file itself was developed by L2.com.  Having dealt with mailing-list vendors before, I recognized much of the subsidiary information that they merged onto the publicly-available voter records.

But if that’s an accurate description —  95M cell phones, 200M voters — then roughly speaking, a bit less than half the L2 file had phone numbers attached to the voter data.

Did this survey draw from persons on the L2 file who had a phone number listed?  Or did it draw from all persons on that file.  The documentation simply says:

The survey is a response rate-adjusted stratified sample of registered voters on the L2 voter file.

I’m pretty sure they meant response-rate-adjusted, that is, they adjusted the likelihood of being sampled based on some prior estimate of likely non-response rate.

In any case, if the U. Penn description is correct, then this is a valid question to ask. Along with the obvious followup:  If it’s persons with listed cell phone, could that matching process — the process that added the cell phone number to the voter record — possibly have induced a bias?

Response rate?

The other thing not stated was the response rate.  They said that 94% of the people they called “were reached” on the phone.  Like this:

 Overall, 94 percent of respondents were reached on a cellular telephone.

But you’re left guessing as to what the actual response rate was.  At least, as far as I could tell, from the documentation cited above.  (The “reached” figure speaks more to the validity of the added phone data, than to the response rate. You can reach me, and I can say “no thanks”.)

Don’t people lie (on average) about how they voted in past elections?

That said, the big advantage this survey has is that it shows a modest win for Biden in these states, in 2020.  That is, it corresponds to the actual 2020 results.

Whatever their methodology goes, it accurately shows that Biden won the popular vote, by a small margin, in 2020.  It’s hard to say that the 2024 projection is hugely biased in some fashion, when you can see that no such bias exists for the actual 2020 results (as estimated from this poll).

Then I got to wondering:  Don’t people lie, after the fact, about having voted for the winner?

The problem is that if I Google anything near that topic, all I get is stuff about the 2020 election.  So any answer to whether or not this is material — if people tend to say they voted for the winner — will have to wait until I figure out some better way to find an answer to that.

 

 

Post #1894: Commentary on the NY Times/Siena College poll results.

 

I find myself grasping at straws, trying to explain away the NY Times/Siena College polling results showing Biden soundly losing to Trump in 2024.

This survey predicts Trump taking five out of six swing states in 2024: Arizona, Georgia, Michigan, Pennsylvania, Nevada.  But not Wisconsin.  Source:  This

Having spent some time down in the details, let me summarize:  A poll that correctly reproduces the 2020 Biden win (in six swing states) now calls for a big 2024 loss. 

Worse, it’s a good poll.  By which I mean, a well-executed poll.  I saw almost nothing in methods that I strongly disagreed with.  (And I used to be in the statistics biz.)

Insert rambling detail here

I have to admit that I woke up just totally pissed off about this poll. After my wife clued me in on it yesterday.  Her response to the results was “people suck and I hate them all”.  Seems like a valid viewpoint.

I just plain wanted it to be wrong.  That’s not science.  I looked for obvious errors, and didn’t see any.  So far.  FWIW.  It’s the gold standard — the best available estimate of how these swing states are likely to vote.

Here’s my take on the main message:

Biden’s too old. 

And other stuff, sure.

Weirdly, the main writeups seem to skirt this issue.  But to my eye, this is something that everybody agreed on.

Separately, smears work, disinformation wins.  Seemed like more than half of everybody think Joe Biden’s dirty, and has taken payments from China and Ukraine.   Which, as far as actual evidence goes?  In any case, one President makes his tax returns public, one does not, I’m gonna stick with the one who does.

Yes but.

And now, from the Democratic side of things, comes a string of “yes, buts.”

There’s some nuance to it, but I think I can boil them down as:

Yes, Biden’s too old.  But if my only alternative to Biden is Trump, then “too old” doesn’t exist.  If Biden’s breathing, I’m voting for him.

And I have some reasons for preferring Biden.  In no small part, it’s fair to expect Biden to assemble a far more competent team than Trump.  Fewer cronies, fewer toadies.  Fewer of his own children, for that matter.  And for sure, with Biden, we’ll likely have fewer Chairmen of the Joint Chiefs mockingly threatened with execution.

So you can “yes, but” it to your heart’s desire.  Yes Biden’s 80.  But Trump’s 77, fat, and his dad died following a period of dementia.)  Yes, Biden sometimes does old-guy stuff, but Trump rarely utters a coherent sentence.  If I gotta listen to one old fart ramble, please let it be Biden, and not Trump.

And there’s that whole fate-of-the-Democracy thing.  We got one joker in the Senate, saving up military appointments.  Hell, what worked for McConnell for the Supreme Court sure ought to work for the military.  Given how much Trump admires dictators, the idea of a military run top-to-bottom by Trump acolytes does not appeal to me.

But he’s stuck.

And I mean Joe Biden.

Is there any way that Biden could withdraw from the race?  I’m not seeing it.

Wouldn’t he then be obliged to support his vice-president, as the Democratic presidential candidate?

Do you think that America is ready to vote for a Black woman, to be President?  Separately, do you think Harris is a good candidate?

My answer is no and no.  I don’t see Harris as a viable winning Presidential candidate.  So Biden’s stuck there.  If he drops out in a normal and reasonable fashion, then the Dems lose in 2024.

So he can’t agree that he’s too old.  Even if he thinks he is.  And he can’t drop out, for that or any other reason.  He options are to fight one more election.  Or to lose.  No reasonable person can expect Biden not to fight for it.

Post #1893: Winter, firewood, soot, Canada

 

 

Normally, about this time of year, I’d start burning my way through two cords of wood, over the course of the winter.

This year, I’m not.

It’s complicated.

Soot uncertainty.

I went through the biggest global environmental problem in heating with wood back in Post G22-058.

In a nutshell, when I burn firewood for heat, the C02 that goes up my chimney came out of the air an average ten years ago.  For that reason, firewood is very close to a carbon-neutral fuel, when viewed over (say) a decade of time.  Over that time period, atmospheric C02 is neither increased nor decreased by the process of growing wood, then burning that wood.

As opposed to say, burning natural gas.  Typically, that was produced some time in the last half-a-billion years or so, and trapped underground.  The C02 from that source definitely adds to the current level of atmospheric C02.

But along with wood burning comes soot.  And even though that soot resides in the atmosphere for just a brief period (typically, two weeks), soot is incredibly effective at capturing the heat from the sun.  Dispersing a microscopic black powder through the atmosphere allows the atmosphere to absorb more light energy?  Who would have guessed that?

Source:  Myhre, G., D. Shindell, F.-M. Bréon, W. Collins, J. Fuglestvedt, J. Huang, D. Koch, J.-F. Lamarque, D. Lee, B. Mendoza,
T. Nakajima, A. Robock, G. Stephens, T. Takemura and H. Zhang, 2013: Anthropogenic and Natural Radiative Forcing. In: Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Stocker, T.F., D. Qin, G.-K. Plattner, M. Tignor, S.K. Allen, J. Boschung, A. Nauels, Y. Xia, V. Bex and P.M. Midgley (eds.)]. Cambridge University Press, Cambridge, United
Kingdom and New York, NY, USA.

Back in 1995, nobody quite knew what the net effect of soot was.  Even through 2014, estimates were uncertain enough that the confidence interval around the point estimate included zero.

That said, you have to go with the most recent evidence.  Based on the 2014 5th report (AR5) of the Intergovernmental Panel on Climate Change (IPCC), I estimated that the warming effect of the soot from my wood stove was just about large enough to offset any benefit from wood burning.  That’s the gist of in Post G22-058.

And that’s why I skipped the firewood purchase this year.

The IPCC sixth summary report was released in its entirety earlier this year.  So it’s worth taking a peek at that, as the estimate for black carbon involved a lot of uncertainty.

(First, though I have to note how different the public debate is now, for the IPCC 6th report, compared to nine years ago, for the 5th report.  For the IPCC 5th report, climate-change denialists went over it with a fine-toothed comb and found an actual substantive error, in a sentence, in a section of the technical portion of the report.  This had to do with the rate of melting of Himalayan glaciers. And, as is their habit, the climate-denial industry then proceeded to play the game of This Changes Everything,  So Believe Nothing You Have Heard.  For the sixth report, by contrast, the release was uneventful, and nobody tried to fabricate some made-up stink about it.  It’s almost as if everyone with sense now realizes that climate change is real, man-made, and causing problems.  And so there is little value in trying to generate new disinformation, because those who still deny that climate change is a real threat are more-than-satisfied with continuing to believe disinformation that was debunked decades ago.)

Interestingly, they’ve revised their estimate of the warming impact of soot way downward, compared to the 2014 report.  (Though still within the 95% confidence interval of the 2014 report).

The best estimates of ... attributed to ... black carbon is substantially reduced. The magnitude of uncertainty in the ... due to black carbon emissions has also been reduced relative to AR5. (Section TS.3.1)

Source:  Page 42, IPCC, 2021: Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 2391 pp. doi:10.1017/9781009157896.

And, in fact, it looks like the estimate of the warming impact of soot is back about where it was in 1995.  Which is about when I decided it would minimize my global warming footprint if I burned wood for (at least some of) my home heating.

Source:  Page 92, reference cited just above.

Without getting further into the details, at face value, the upshot of this most recent change is that heating your house with wood, in a modern air-tight low-emissions wood stove, probably offers significant net benefit in terms of global warming footprint.  Based on this most recent estimate of the impact of the resulting soot.  Assuming I did my calculations correctly last year.

Local air pollution

This year’s air pollution alerts from Canadian forest fires have made me a lot more sensitive to the issue of air pollution from wood fires. In the past, I’ve just turned a blind eye to that, mostly because as far as I can tell, I’m the only person within blocks that actually burns wood for heat.

Air pollution from an isolated wood stove does not have the same public health implications as air pollution from Canadian forest fires.  That’s because you have to be in the exhaust plume from my stove to be affected by it.  By contrast, you were breathing Canadian soot no matter where you were, and no matter when.  It’s the difference between a brief exposure, walking past my house (say), and breathing it 24 hours a day.

So, really, it’s more a question of what I’m doing to the air that I and my neighbors breathe.  And for that, the key question is how particulates generated by my wood stove, at my property line (i.e., entering the public domain) compare to the particulate levels we saw during the Summer 2023 air pollution alerts?

I suspect that the only way to tell, with this one, is to measure it.  Which I will, the next time I light a fire in my stove.

For now, let me work through the basics, given that this stove is EPA rated to produce no more than 2 grams of soot per hour.  A good round number for “too much soot in the air” is, say, 100 micrograms per cubic meter for total particulates.  That would trigger an “unhealthy” reading for PM 2.5.  To get down to that level, an hour’s worth of soot from my stove would have to be diluted into … 20,000 cubic meters of air per hour.

Or about 333 cubic meters of air per minute.  In order to dilute the smoke from my wood stove down below the “hazardous” level for particulate matter.  That’s a cube of air roughly 18′ on a side.  That seems like a high-but-plausible rate of dilution.

There is also a sense that if you can smell wood smoke, you are breathing in pollutants.  And that may well be true — the smell must come from somewhere.  That said, a quick look at some scholarly papers suggests that there isn’t a tight correlation between the smell of smoke and the density of particulates in the air.  (As evidenced, I guess, by the Canadian forest fires, where there was no smell of wood smoke in the air, but particulate levels were high).

So, before I even lay my first fire of the season, and get out my recently-purchased air quality meter, I’m guessing that this is an open question.  I can surely smell wood smoke, at ground level, at least part of the time that I’m buring wood.  The next step is to measure it and see if I’m pushing unhealthy levels of particulates out into my adjacent neighborhood.