Anything related to transportation, including cars, traffic, other modes of transport, and so on.
I knew that DC Metro ridership was down during the pandemic, and hadn’t really recovered. But I was still shocked when I parked in the nearly-empty lot at the Vienna Metro, on a weekday morning last week. Continue reading Post #1892: Vienna Metro has lost its groove.
Bottom line: Per mile, risk of death on a bicycle is about thirteen times higher than risk of death in a car/SUV/van. Calculation shown below.
I read a story in the Washington Post today, about a woman who was killed while bicycling, in the bike lane, alongside River Road in Bethesda. Crushed by a careless commercial truck driver making a right turn. Leaving behind a husband and two young kids.
The truck driver was given the maximum sentence allowed by law, which in this case was a $2000 fine. And a brief moment of shame in court. He’s still on the road, driving a truck.
I looked up the accident scene on Google, and it was the worst kind of grudging, cheap, zero-effort retrofit urban bike lane that the very least of your tax dollars can produce. Based on historical images, they took a narrow, disused shoulder of a 35-MPH urban arterial highway, and painted little arrows and bike icons in it.
Well, there’s your bike lane, right there. Problem solved. The result of that zero-effort accommodation of bicyclists is every bit as safe as you might reasonably expect.
Above, the middle red circle is the site of death. It’s just one of many driveways opening into the busy commercial establishments that line the road. It’s located just 500 feet from the Capital Crescent Trail, a dedicated bike path whose road-crossing bridge can be seen circled in the background. Which is almost certainly why they bothered to re-paint the road shoulder.
In the foreground is a sign. Based on Google street view, that sign was only placed there a few months ago. If you don’t routinely bike in an urban area, you’d think that sign was there to remind motorists to use caution, and look before they turn. But for that purpose, in this context, a sign like that is useless. Motorists don’t even perceive signs like that, in the crowded visual field of an urban motorway, at 35 MPH and up. The actual, practical purpose of the sign is to warn bicyclists and pedestrians that they are in the middle of a war zone, and that they should act accordingly if and as possible.
But in this situation, there’s not much a bicyclist can do. The bike lane appears to be just under 3′ wide. The curb is about a foot to your right, so there’s no escape in that direction. Your life depends on the caution and good sense of the drivers passing a couple of feet to your left.
A slender reed, for sure.
Yes it is.
And, for some reason, this appears to be an answer that absolutely infuriates bicycle advocates. Not because they don’t want to make roadways safer for bikes. But simply because they don’t want to believe that there are significant downsides to bicycle transport in America. This, even if everybody grasps what a drag it is to (e.g.) bike in bad weather.
(And, to be clear, I’m a lifetime bicycling enthusiast. But I’m also a realist.)
Years ago, I did the homework to answer this question, to my own satisfaction. I came up with an estimate that bicycling is about ten times as dangerous as driving, per mile traveled. That’s in terms of risk of death. It’s even higher in terms of risk of injury requiring medical attention. Those specific calculations are lost in the mists of time. So I thought I might update and document that here.
Any estimate of bicycling safety ends up combining data from two separate sources. That’s always a risk for accuracy, but it is what it is.
Information on traffic-related deaths comes from a motor vehicle crash reporting system maintained by the National Highway Transportation Safety Administration, the Fatality Analysis Reporting System. Whatever its limitations, that’s the U.S. gold standard for counting traffic-related fatalities in the U.S.
(Secondarily, if you have an interest, you can use nationally-available hospital statistics from the U.S. Public Health Service’s Healthcare Cost and Utilization Project to find the number of hospitalizations and outpatient visits related to bicycle accidents. But non-fatal injuries actually show an even grimmer picture for bicycling versus driving, so it’s probably sufficient to settle on an estimate of risk-of-death while bicycling versus driving, per mile.)
So, bicyclists accounted for about 2.4% of all U.S. traffic deaths in 2020. That figure is roughly constant over time.
Information on bicycle-miles traveled comes from the National Household Travel Survey (NHTS). This is based on a log-diary survey of thousands of U.S. households, capturing how and why they traveled over the course of a week. Near as I can tell, it’s the only nationally-representative information on actual use of bicycles versus other modes of transportation.
Source: 2017 National Household Travel Survey
Based on that large, nationally-representative log-diary survey, bicycle transport accounted for 0.2% of all U.S. household transportation, or about 8.5 billion bicycle-miles per year in 2017. (Sounds like a lot until you realize there are about 330 million U.S. residents, so that works out to about 25 bike-miles per person per year.)
We have to re-calculate the percentages above, to restrict this to cars versus bikes. After that, it’s just simple math.
Yes, bicycle transportation really is as dangerous as it looks, as you drive along the road.
Using two gold-standard U.S. databases, bicycling appears vastly riskier than driving a car. In this most recent calculation, I estimate about 13 times higher risk of death, per mile, on a bike, versus in a car. That’s reasonably consistent with the estimate I got years ago.
And, as I recall, if you expand to non-fatal injuries requiring medical attention, the relative risk is actually much higher. More like 50 or 60 times the risk, per mile. That’s for the obvious reason that a collision that produces only minor bumps and scrapes to car occupants can produce severe wounds to an unprotected bicyclist.
Four things are worth noting.
First, the absolute risk is low. If you bicycle 1000 miles a year — which is a lot — your risk of death-via-bike is about 0.01% per year.
Second, for older adults, the exercise benefit vastly outweighs the crash risk. This is another one that I did the homework years ago, then lost the analysis somewhere. For the average 65-year-old man, all-causes risk of death is about 2% per year. Best available research suggests that frequent vigorous exercise roughly cuts that in half. The health benefits of frequent bicycling likely outweigh the risk-of-traffic-death by an order of magnitude or two.
Third, on paper at least, walking around traffic is more hazardous than bicycling. I’m not sure to the extent this is driven solely by work-related pedestrian accidents in big cities. But whatever the cause, this too seems plausible. In effect, we let amateurs drive 3-ton pieces of machinery, at high speed, around crowds, with virtually no enforcement of rules or penalties for engaging in risky behavior. It’s a wonder that so few pedestrian deaths result.
Finally, if you do a deep dive in the FARS database, you’ll find that dead pedestrians and dead bicyclists have something in common with dead drivers. An astounding fraction of them are dead drunk at the time. Roughly half, in each case. The moral of the story is that BUI and WUI are maybe not as deadly to others as DUI, but they clearly up your risk of death on the roadways.
But in this case, that’s irrelevant. It was broad daylight, and the victim was returning from a school function for her kids. The death was just the result of a toxic combination of thoughtless, zero-effort bike lane design, and bad luck. Ten seconds sooner, or ten seconds later, and she’d have been fine. It’s just an unavoidable risk of bicycling in most urban areas of the U.S.
This is another post on why plug-in hybrids are the right technology for the long transition to fully-electric transport. Continue reading Post #1844: Converting a gas fill-up to watts.
It has been a long time since I last bought a used car.
I have forgotten just how sleazy the low end of the used car market can be.
But I’m getting educated in a hurry.
Today’s lesson in low-end used cars? A few weeks back, I was interested enough in an older Nissan Leaf that I scheduled an appointment with the dealer, to have a look at it. Then I did my homework, and cancelled the appointment.
And, foolish me, I figured I at least owed the guy an explanation of why I wasn’t interested. Because that’s what reasonable people do.
The ad for the car claimed excellent battery health, and a 110-mile range, per the independent estimate from Recurrent.com. By contrast, once I learned to read the “gas gauge” of a Nissan Leaf, photos of the dashboard revealed barely 60 miles of range left, as well as a battery that was in mediocre health. Via email, I told the dealer that’s why I was no longer interested. The car really didn’t have adequate range left.
I continue to track the ad for that car, just to try to get a handle on the used car market.
In response to my explanation of that cancelled appointment, what do you think the used car dealer did to the ad for that car?
If you guessed “c”, then you’re a lot less naive about the used car market than I am. Or was.
As an economist, I really shouldn’t use the word “sleazy”, when the behavior is rational. The dealer represents seller, plain and simple. The dealer’s job is to get the best price for the seller, within some reasonable timeframe. Anything that increases the odds of selling the car, without getting thrown in jail, is fair game. So, if fuzzying-up the information on range might help sell the car, then fuzzying should occur. It’s up to the buyer to understand that and act accordingly.
In fairness, the dealer keeps dropping the price of that 2016 Nissan Leaf. In any case, I’ve already made up my mind that I don’t want anything earlier than a 2018 Leaf, due to the rapid degradation of the battery in earlier model years of Leafs.
The lesson here is that it’s still a used car, even if its electric. With everything that buying a used car entails. Just because it’s eco-friendly doesn’t mean the dealer is friendly. The upshot is that in trying to be a straight shooter, in a room full of crooks, all I did was help the crooks to be better crooks.
In addition to that 2016 Leaf, I have been tracking three 2018-or-later Leafs. These have a different battery chemistry from older Leafs. They retain their battery health and range much better than the pre-2018s and are priced accordingly.
Of the three cars I begin tracking less than two weeks ago, two have already sold.
Assuming that’s not just some kind of fluke, either I have an exceptional eye for a good deal, or the market for a reliable used EV is pretty hot. At least around here.
Official U.S. Consumer Price Index data are all-but-useless for judging long-term trends in the price of new and used cars. I went through that in Post #1836.
Source: Bureau of Labor Statistics, via the Federal Reserve of St. Louis FRED system
The quality adjustment embedded in the CPI car price data mean that the price trends as published by the Bureau of Labor Statistics have nothing to do with how much money you’ll need to shell out to buy a basic car. Such as Toyota Corolla, shown in yellow below.
But if car prices move fast enough, the actual change in prices will swamp the BLS quality adjustments. And so, for sharp short-term price movements, the BLS data aren’t too bad. From the BLS, we can see that used car prices peaked at the end of 2021, and have been mostly falling since.
Source: Underlying data from the St. Louis Federal Reserve (FRED)
The BLS does not appear to publish any data separating electric vehicles from other types of vehicles. So I have to turn to privately-produced price statistics if I want to get a handle on what’s happening to EV prices, as distinct from other types of vehicles.
And that’s where things turn a bit odd. Because, as far as I can tell, a lot of private-sector price estimates show that the price of used EVs is plummeting.
Here are two such estimates, from what I believe to be independent data sources:
The devil is in the details.
The iSeeCars study is a study of used cars one to five years old. And the measured price reduction in that segment was driven by Tesla’s decision to cut the price of its new cars. More-or-less, what they measured is that the price of used Teslas fell about 30%. In addition, it appears that they do not adjust for changes in the mix of vehicles sold, but simply take the change in the average asking price for a used EV.
The Recurrent study is also a study of used cars one to five years old. It appears to be based on the simple average of the asking prices of seven common used EVs and PHEVs. And, as with the iSeeCars study, a big chunk of the reduction is attributed to Tesla’s decision to cut the price of their new cars substantially.
That said, the Recurrent study shows a corresponding increase in (e.g.) the fraction of the used EV market offered for sale at less than $25K. I’m pretty sure that excludes most Teslas. The inference would be that these price declines affected the broader market, not just Tesla.
When all is said and done, my guess is that I should be in no hurry to buy a used EV. Prices for relatively new models (one-to-five years old) appear to be falling, in large part due to new-car price cuts by market leader Tesla. I don’t perceive that among low-end models, in my geographic area. But its possible I simply tracked an unusual small sample of cars.
Although the price trends may be murky, one aspect is clear. I’m still something of a babe in the woods when it comes to buying a used EV. I need to get a lot smarter before I put my money down on a used car. Even if it is an eco-friendly electric car.
My wife and I just returned from a brief vacation in Ocean City (OC), Maryland.
Our annual OC vacation has changed since our kids have grown up. Without the need to entertain the kids, the beach experience becomes a lot more, eh, ritualized, for want of a better term. Continue reading Post #1838: Two electrical issues from our recent vacation.
Source: WTOP.
There was an article today on the local news-radio website (WTOP) regarding speeding in school zones. I took note, because I routinely drive through one of those zones where Fairfax County VA operates speed cameras. The zone is clearly marked, and you’d have to be blind to miss it, as shown above.
And yet:
In total, 23,431 cars were caught going 10 or more miles per hour above the speed limit in April, May and June combined.
I supposed I should be impressed by the sheer numbers. But instead, a completely different figure caught my eye: They only ticketed folks for going at least 10 MPH over the limit.
First, I thought it was intemperate of the reporter to note that exact figure. Anybody reading the article realizes that there’s no risk of a ticket at anything up to the posted speed plus 9 MPH. So, presumably, if generally known, that now becomes the de facto speed limit.
But second, I’d heard that same figure before, a few years back, in a discussion of red-light cameras and speeding cameras in Vienna, a town in Fairfax County. There it was phrased as “we don’t ticket unless they are going at least 11 MPH over the posted limit.” The explanation given at the time was that Fairfax County courts would not accept cases for any infraction less than that.
Short answer is, yes and no.
In theory, by Virginia statute, you can get ticketed for traveling one mile an hour over the speed limit in a residential area. This is my interpretation of § 46.2-878.2 of Virginia statute, which says :
Operation of any motor vehicle in excess of a maximum speed limit ... in a residence district of a county, city, or town ... shall be unlawful and constitute a traffic infraction punishable by a fine of $200, in addition to other penalties provided by law.
The black-letter law provides no slack. If you’re in a residential district, on a highway (meaning, in Virginia, any public alley, street, road, or highway), and you’re going a mile over the limit, you can, in theory, be ticketed and will owe a minimum of $200.
Except that the law spells out a different set of penalties for drivers caught by speed cameras in school zones. My interpretation is that because the process is, in effect, automated, they cut drivers a lot more slack than they would if they’d been pulled over, in person, by a uniformed officer.
In the case of speed cameras in a school zone (§ 46.2-882.1), emphasis mine:
1. The operator ... shall be liable for a monetary civil penalty ... if such vehicle is found ... to be traveling at speeds of at least 10 miles per hour above the posted ... speed limit ... . Such civil penalty shall not exceed $100 ... ... 4. Imposition of a penalty pursuant to this section ... shall not be made part of the operating record of the person upon whom such liability is imposed, nor shall it be used for insurance purposes in the provision of motor vehicle insurance coverage.
There appears to be no hard-and-fast rule regarding ticketing for how much “slack” you get, speeding in a residential area in Virginia. The plain language of State law in Virginia law says that if you exceed the posted limit, you can be ticketed. I believe that pre-empts any local law, as we are a Dillon Rule state. That is, local governments can only make their own rules where the Commonwealth grants them permission to do so. And nothing in Commonwealth statute appears to do that, with a few limited and explicit exceptions spelled out in the law.
Except that “ten miles over the limit” is written into law, in Virginia, for speed-zone cameras. There, the Commonwealth leans heavily in the direction of protecting drivers’ rights, and avoiding Big Brother information harvesting. So, in exchange for what is basically an automated process, you face a small fine. There’s a monetary penalty, but (as I read it) no points on the license.
First, if you are speeding, in Virginia, you lose any claim to having right-of-way. So if some bonehead does something to get you in a car accident, where you had the right of way, but you were speeding at the time … tough luck. You cannot claim right-of-way while you are speeding.
§ 46.2-823. Unlawful speed forfeits right-of-way. The driver of any vehicle traveling at an unlawful speed shall forfeit any right-of-way which he might otherwise have under this article.
The reason for that is pretty clear. Traveling at excess speed makes it difficult for other drivers to judge whether or not an accident will occur.
We had a horrific accident in this area, last year, that is a classic illustration of that. The culprit was a bozo who was driving a BMW about 80 MPH in a 35 MPH zone. His car got struck by a car turning left, and his car subsequently jumped the sidewalk and killed two high school student who were on the sidewalk, walking home from school.
Normally, the car going straight has the right of way. Should the car turning left have therefore been charged with the accident, for failure to yield right-of-way? I don’t think any sane person would suggest that. If nothing else, on a curved road, excessive speed of that magnitude more-or-less prevents drivers from seeing you coming in time. The accident was entirely the fault of the speeding driver.
Second, if you speed significantly in areas with red lights, you will run red lights.
Not may, will.
This point is courtesy of Road Guy Rob on YouTube. Yellow light duration is set based on expected traffic speed. (Plus regional variation, I guess). High-speed roads have long yellow lights, low speed roads have short yellow lights. In both cases, the length of the yellow allows drivers that are far from the intersection to stop before the light turns red.
If you drive at high speed, on a low speed road, there will be a stretch of pavement, and a rage of excess speeds, so that if you see the yellow light while you’re in that zone, you will literally be unable to avoid running the red. That’s because, between your reaction time and the car’s stopping distance, your car will travel much further than the engineers who set up the light expected. If you are within just the right range of excess speeds, if you see the light turn yellow, you both a) can’t make it through the intersection before the light turns red, and b) can’t stop before entering the intersection. No matter what you do — hit the brakes, hit the gas — you go through the red light.
And so, at some level, excessive speeding and running red lights go hand-in-hand. There’s a certain pleasing symmetry to that. My guess is, the folks who don’t care about the first, don’t much care about the second either.
I was able to start riding my bicycle again, this past week, after more than a year of being unable to do so. That got me to thinking about how personal transportation has turned topsy-turvy in the 25 years that I’ve been pedaling this same semi-recumbent bike.
Continue reading Post #1785: My car gets better mileage than my bicycle.
The Washington Post just published one of its weekly anti-Electric-Vehicle (EV) screeds.
This thing: https://www.washingtonpost.com/climate-environment/2023/04/15/electic-cars-biden-epa-climate/
And, God help me, I just spent a couple of hours posting comments. I gotta stop doing that.
My wife suggest that I compile and post all my comments. Think of it as a collection of short, related essays.
Sometimes, thoughtful comments in the Post allow me to discover something new. As in red, below. But my main takeaway from all this is that I have to stop commenting on Washington Post articles. Continue reading Post #1781: No comment on electric vehicles
This is a post about what “Yield” means, as in, what you must do to obey a yield sign at an intersection. Continue reading Post #1780: Yield!
Weird, eh? I’m happy to rely on a (mostly) battery-powered car. But I don’t want a battery-powered lawn mower. Even though I used a plug-in electric mower for years.
I swore off battery-driven power tools years ago. So, for me, it’s not as if this is some new stance.
In this post, I explain why. Why I’m not going for a battery-powered mower. And why I no longer buy any power tools that run on batteries.
Let me emphasize that my decision isn’t due to ignorance. If anything, it’s because I’ve had too much experience with big lithium-ion batteries.
Practically speaking, your sole option for a walk-behind battery-powered mower is lithium-ion batteries. There have been some riding lawn mowers powered by lead-acid batteries. But I don’t think there’s anything on the market today not powered by lithium-ion batteries.
Almost no lithium-ion batteries are recycled in the U.S.
I’m acutely aware of this because a) I bought a 200-pound lithium-ion add-on battery pack for my wife’s Prius in 2008, and b) recycling of those big lithium-ion batteries has been just around the corner for the past 15 years. I think my most recent post on that was Post #1715.
Still don’t believe that lithium-ion is rarely recycled? Here’s a handful of relatively recent references.
That last reference is particularly illuminating. Read down to the part where the Federal government is still at the point of offering cash prizes for anybody who can figure out how to do it cost-effectively. Its not merely that lithium-ion batteries aren’t recycled, it’s really that there’s not even one good, standardized, agreed-upon process for doing it, let alone doing it cost-effectively.
Post #1712 has the details, but the reason for the lack of recycling is obvious. It costs money. Reportedly, Tesla currently pays $4/pound to recycle is lithium-ion batteries. Even with that, the cost of post-recycled lithium is higher than that of virgin lithium, making it an uneconomic source for production of new batteries.
Still, some stores — around here, notably Home Depot — have boxes where you can drop off old batteries weighing under 11 pounds. That should cover most lawn tool batteries.
That’s free to you because Home Depot covers the cost of processing those via call2recycle. This is an organization whose funding comes from battery- and battery-powered device manufacturers, or from organizations willing to pay to recycle those batteries. For example, their board of directors has representatives from Panasonic, Sony, Energizer, and Duracell, among others, based on their 2021 annual report.
You can see examples of their retail pricing on this page. It looks like they charge about $2.50 a pound to take boxes of mixed rechargeable batteries off your hands. So Home Depot is paying on-order-of $12 to allow you to dispose of a 5-pound lithium-ion lawn mower battery.
What happens after that is a bit unclear to me. For sure, the value of the materials recovered appears trivial. Here’s their 2021 Annual Report, showing revenue sources. Less than five percent of their revenues comes from the materials recovered from those batteries.
Source: call2recycle 2021 annual report.
They do not break out their collection and recycling costs separately. Combined, those account for the bulk of their costs.
At any rate, they are clearly at least paying to have those batteries disposed of properly. What fraction of the materials actually ends up in new products — is actually recycled — is not possible to determine from their annual report.
Interestingly enough, when I look up their lithium-battery recycling partners, the only U.S. partner appears to be a 2021 startup. Which again seems to emphasize just how iffy lithium battery recycling remains, at this time.
Fifteen years. For fifteen years, I’ve been living with a 200 pound LiFePO battery pack. And for fifteen years, large-scale lithium-ion battery recycling has been just around the corner. Which is right where it is today.
Which is a fancy way of saying, if you want to keep using the tool, you have to keep buying batteries.
We replaced the nickel-metal-hydride traction battery in my wife’s (now son’s) 2005 Prius somewhere around 178,000 miles. Doing the math, the cost of that new battery ate up roughly half of the total lifetime savings in gasoline costs, from driving that efficient hybrid compared to a similarly-sized non-hybrid 2005 vehicle.
But it’s not just the dollar cost. It takes quite a bit of energy to manufacture batteries, something that contributes to the multi-year “payback period” of a Prius relative to a non-hybrid automobile. For the first couple of years that you drive a hybrid, from a carbon-footprint standpoint, all you are doing with your lower fuel use is paying back the higher energy cost of the vehicle’s manufacturing.
In particular, worst-case (made-in-China, meaning, made using coal-fired electricity), large-format lithium ion batteries result in the release of roughly 200 kilograms of C02 per KWH of battery capacity (calculated from this MIT reference, 16 metric tons per 80 KWH battery pack).
And so, creating a typical lawn-mower battery — 0.3 KW (72 volt, 4 amp-hour) would result in (200 KG/KW x 0.3 KW * 2.2 lbs/KG = ) 132 pounds of C02 released into the atmosphere.
I use 2 gallons of gas a year to mow my lawn. That generates about 40 pounds C02 per year. The upshot is that even if my electricity were carbon-free, I’d spend the first three years of battery-powered lawn mowing merely paying back that initial 132-pounds-of-C02 debt, for the manufacture of that disposable battery.
That’s not a huge surprise, to those of us who have been using big battery-powered objects. It was an estimated two year payback period for a 2005-era Prius, where the battery and motors didn’t really power the entire car. So, a three-year payback period for a small tool that’s entirely battery-powered? To me, based on my experience with the Prius, that seems entirely plausible.
As for the energy cost of the rest of it, I’ll just point to the high energy cost of smelting copper. Electric motors require quite a bit of that, which is another reason hybrids require more manufacturing energy than non-hybrid cars. Plausibly, depending on expected lifespan, there may be no manufacturing energy savings in the non-disposable portions of the devices.
For an extremely-long-lived battery, such as one used in a car, that payback period usually isn’t much of a consideration. You’re saving a ton of fuel, and the battery will typically last well over a decade. Overall, it’s a winner, even if you fully acknowledge the energy cost of producing the battery.
Here’s the kicker: How long do those lawn-mower batteries last? Every website I visit seems to give the same answer of three-to-five years. So they might last long enough to pay back that initial carbon-footprint debt.
The upshot is that a lithium-ion powered lawn mower is a fine way to reduce local air pollution. It may not be such a winner from the standpoint of reducing your carbon footprint. And since global warming/carbon footprint is my main concern, I’m not hugely attracted to those devices from an environmental standpoint.
In addition, knowing what I now know about lithium-ion batteries, I’d bet on the lower end of that three-to-five-year range. My wife’s new Prius — a Prius Prime — arguably contains a $12,000 lithium battery pack. With no warranty to speak of. So I got kind of serious about not trashing that. And that’s when I learned the rules for lithium-ion batteries. See Post #1703.
The rules, in brief: Lithium-ion batteries don’t like heat. They don’t like to be fast-charged. They don’t like rapid rates of discharge, either. And they really don’t like being worked from fully charged to fully dead. They much prefer shallow charge-discharge cycles.
And yet, every manufacturer seems intent on using them in all the wrong ways, in mowers. These will see highest use in the heat of summer, and typically be stored in a non-climate-controlled space. Everybody seems to charge their lawn-mower batteries at a “1 C” rate of charge or higher — from dead to fully charged in one hour. (Presumably, that’s to all ow you to swap batteries continuously and mow very large lawns.) I’m pretty sure manufacturers allow the full capacity of the battery to be used, unlike cars that reserve the top and bottom 10 to 15 percent as a buffer against over– and under-charging. (That’s why a 72-volt battery pack can be advertised as 80 volts, because once you’ve absolutely fully charged it, that’s what it’ll read, despite the fact that charging it to that degree is bad for battery life.)
Here, I’ll just refer to the highest-rated 21″ walk-behind battery powered mower on Amazon. This is the Greenworks Pro 80V 21″ model, with 4.0 Ah battery.
On Amazon, the complete mower, with battery and charger, is $425. But the replacement 4.0 Ah battery, by itself, costs almost $300.
In short, your cost of the replacement battery is 70% of the total cost of the functioning lawn mower. And, as with power tools of all sort, manufacturers go way out of their way to make sure that only their batteries will fit their tools.
This, more than anything else, is why I swore off battery-powered shop tools. It’s the monopoly-exploitation aspect of the battery replacement. Once you’ve bought into a particular manufacturer’s line, they’ve got you. And as far as I was ever able to tell, generic batteries manufactured to fit those tools are all completely dreadful. So if you want a battery that works, for that name-brand tool, you pay that name-brand price.
Once I bought my third $45 battery pack, for my $60 drill, I did eventually figure out that a battery-powered drill is an expensive way to make holes in stuff. That drill eventually got to the point where battery packs were no longer available. (Which, if you own one long enough, will happen.) At that point, it too became just another particle in our great national solid waste stream. And was replaced by a corded drill.
This is more of an irritation than a point of substance. But take any battery-powered lawn mower on the market, and try to find out the peak power of the electric motor, expressed either as kilowatts or as horsepower. Nobody will tell you that basic information.
At some level, the average power output is just basic physics. The mower above has a 72-volt, 4 amp-hour battery, and claims to be able to run for an hour on that. That should be sufficient to cut my half-acre lawn.
But do the math. How much energy is at your disposal, for that hour of mowing? Well, 72 volts x 4 amps = ~300 watts of average instantaneous output. Or, over the course of an hour, you have 0.3 KWH of power available to you, to accomplish your hour of mowing. For sure, your peak power output will be much higher than that. But if that battery is going to last an hour, it can’t put out more than an average of 300 watts, over that hour.
One horsepower is about 750 watts. So the average available power output is less than half a horsepower, if you’re going to get your hour of mowing out of that battery. Again, peak output will clearly be many multiples of that. But that’s what you have, to get through your lawn, on average, over the course of an hour.
In my case, there are parts of the lawn, at times of the year, that nearly stall the Honda 3.3 KW gas engine that runs my mower. I would love to know that some prospective battery-powered mower has a peak power output that meets or exceeds that 3.3 KW instantaneous power output.
But here, I bring up the last thing I know about lithium-ion batteries. If that battery could, in fact, produce 3.3 KW of instantaneous power, it would be discharging at more than a “10 C” rate. (That is, at that rate, the battery would be dead in less than one-tenth of an hour.) Discharges at rates like that are unambiguously bad for battery life, for traditional cylindrical-design lithium-ion cells. So even if it could match the peak power of my current mower, I’m not sure I’d want it to.
In other words, just as was true for my old corded Black-and-Decker, I’m pretty sure that the mower will get through my lawn. But I’m also pretty sure that I’m going to have to “baby” it when the going gets really tough.
But short of buying one and using it, there’s no way for me to tell, because manufacturers do not disclose peak power output of these mowers. And so, how well will some battery-powered mower cut through stands of uber-thick Zoysia grass?
Instead of providing me with the concrete information that would allow me to judge that, manufactures require that I take a guess. And when I see something like that, I assume it’s because their product would appear in an unfavorable light, if that information were disclosed.
Let me put it this way: If those battery-powered lawn mowers had peak power that exceeded that of a typical gas mower, you can bet that manufacturers would crow about it. So I think the absolute silence regarding peak power output tells me more-or-less all I need to know.
For the time being, I’ve decided to continue using a gas-powered lawn mower. It’s a modern overhead-valve design, and (best guess, see prior post) mowing produces as much smog-forming pollution per hour as driving a mid-2010s-era sedan for an hour. That’s clearly a downside, compared to battery-powered mowing, but not an extreme one. For good measure, I’ve tossing my antiquated gas can in an effort to keep my gas-powered mowing as clean as possible.
My main environmental concern is global warming, and it’s not clear that a battery-powered mower offers much advantage there, compared to gas. That’s due to the carbon-intensive nature of lithium-ion battery production and the relatively short expected lifetime of those batteries in fairly harsh use conditions.
Otherwise, not switching to battery-powered mowing is mostly a question of avoiding annoyances. No mower maker will bother to tell me peak power. So I suspect that will be lacking. Each mower maker uses proprietary batteries. So I expect to pay an outrageous amount for them.
And the whole lithium-ion battery-recycling thing is one big question mark. Yes, you can drop your dead lawn mower batteries off at Home Depot, and Home Depot will cover the cost of getting them recycled, to some degree. The degree to which the material in these batteries is actually re-used is far from clear.
So that’s it. I saw a compelling reason and significant gains from switching car transportation to electricity. There, at issue was a considerable amount of gasoline burned per year, batteries with an extremely long projected life-span, and some guarantee of responsible end-of-life recycling via Toyota. Maybe. And the driving experience is better under electricity than with gas. For mowing the lawn, by contrast, at issue is just two gallons of gas a year, there’s no clear benefit in terms of carbon footprint, and I’m betting that it’s harder to mow with a battery-powered mower than with a modern gas mower.
So this is one area where I’m not going to electrify the task.
