You just need to lower down the windows. Easy.

The battery heater in BEVs does NOT use water-based coolants at all because of the risk in case it leaks. Instead, they use glycol. Tesla even has a sensor that will disable the HV battery if it detects a conductive liquid in the battery loop.

Let's get some chemistry to help!

On average, the rate of chemical reactions goes up by 2x for every 10C of temperature increase. If your battery is at -20C then it produces about 12 times less energy than at 15C. A typical car battery can produce about 300kW of power, so that still leaves you with 25kW (or 33 horse power). A typical battery is about 400kg for the cells themselves, and apparently the cells have specific heat capacity of 800 J/kg/C, so heating them at 25kW will require 448 seconds.

But heating the battery _improves_ the discharge rate, so you get a nice differential equation. If you solve it, the resulting time is around 240 seconds or 4 minutes.

In reality, modern EVs drive just fine in Midwestern weather without ANY pre-heating. You get very sluggish performance for the first ~10 minutes while the battery warms up, but the car is perfectly drivable.

This study is BS. I have a 2018 Model 3 with resistive heating, and I did many road trips in sub -20C conditions. Heating a cold-soaked battery from that temperature to 10C takes about 5kWh, or around 7% of the total capacity. You typically can do that on "shore power" while the car is plugged in but you can do that unplugged. After that the battery gets enough heating from its internal inefficiencies.

The major energy sink is actually heating the _cabin_. People tested driving a Tesla Model 3 at -20C without any heating, and the range is around 86% of the normal.

So the range impact has NOTHING to do with the "battery chemistry" or "fundamental problems with lithium". It's just a question of using more energy to drive a given distance. Good news is that it can be solved by just making the battery larger.

Class 1 and 2 e-bikes limit assist to 20 mph, not 15. You can ride them faster than that, but you have to provide the power. 20 mph is well above what most recreational cyclists can maintain on a flat course, so if these classes arenâ(TM)t fast enough to be safe, neither is a regular bike. The performance is well within what is possible for a fit cyclist for short times , so their performance envelope is suitable for sharing bike and mixed use infrastructure like rail trails.

Class 3 bikes can assist riders to 28 mph. This is elite rider territory. There is no regulatory requirement ti equip the bike to handle those speeds safely, eg hydraulic brakes with adequate size rotors. E-bikes in this class are far more likely to pose injury risks to others. I think it makes a lot of sense to treat them as mopeds, requiring a drivers license for example.

Would treating them as mopeds be so bad?

What weâ(TM)re looking at is exactly what happened when gasoline cars started to become popular and created problems with deaths, injuries, and property damage. The answer to managing those problems and providing accountability was to make the vehicles display registration plates, require licensing of drivers, and enforcing minimum safety standards on cars. Iâ(TM)m not necessarily suggesting all these things should be done to e-bikes, but I donâ(TM)t see why they shouldnâ(TM)t be on the table.

I am a lifelong cyclist , over fifty years now, and in general I welcome e-bikes getting more people into light two wheel vehicles. But I see serious danger to both e-bike riders and the people around them. There are regulatory classes which limit the performance envelope of the vehicle, but class 3, allowing assist up to 28 mph, is far too powerful for a novice cyclist. Only the most athletic cyclists, like professional tour racers, can sustain speeds like that, but they have advanced bike handling skills and theyâ(TM)re doing it on bikes that weigh 1/5 of what complete novice novice e-bike riders are on. Plus the pros are on the best bikes money can buy. If you pay $1500 for an e-bike, youâ(TM)re getting about $1200 of battery and motor bolted onto $300 of bike.

Whatâ(TM)s worse, many e-bikes which have e-bike class stickers can be configured to ignore class performance restrictions, and you can have someone with no bike handling skills riding what in effect is an electric motorcycle with terrible brakes.

E-bike classification notwithstanding, thereâ(TM)s a continuum from electrified bicycles with performance roughly what is achievable by a casi recreational rider on one end, running all the way up to electric motorcycles. If there were only such a thing as a class 1 e-bike thereâ(TM)d be little need to build a regulatory system with registration and operator licensing. But you canâ(TM)t tell by glancing at a two wheel electric vehicle exactly where on the bike to motorcycle spectrum it falls; that depends on the motor specification and software settings. So as these things become more popular, I donâ(TM)t see any alternative to having a registration and inspection system for all of them, with regulatory categories and restrictions based on the weight and hardware performance limitations of the vehicle. Otherwise youâ(TM)ll have more of the worst case weâ(TM)re already seeing: preteen kids riding what are essentially electric motorcycles that weigh as much as they do because the parents think those things are âoebikesâ and therefore appropriate toys.

LOL. A simple EV drivetrain is easy. A modern EV? It's an engineering work of art, with specialized power electrics, electric motors with power density that is insane, etc.

A lot of complexity is not apparent to classic mechanical engineers, but it's no less real. If anything, it's the gasoline engines that require no real expertise anymore.

Semantics. The last years of Chinese schools are focused on gaokao. It's THE test in China, even though technically it's "just" a university entrance test. So pretty much everyone ends up taking it.

There's also Zhongkao which also will cause poor US snowflake students to become a gibbering mess if they had to take it.

The entire country of China. This is the university entrance exam ("high exam"). They also have a zhongkao ("middle exam") to get admitted into the high school.

That's why I mentioned gaokao. Look at its sample problems: https://www.reddit.com/r/math/... Notice a distinct lack of calculator problems and long division?

SAT, ACT, whatever. They both suck because they are WAY too easy.

No, I'm not. Studying any topic is hard work that requires a lot of exercise and practice. And you need objective criteria to measure your progress. You can do competition-style measurements, where you pit yourself against other people. But it's not practical for math. So you're only left with "track running" style measurements, i.e. testing.

Yeah, yeah. The 'dynamic' education will allow synergy with AI-based information workflows empowered by laser-focused goals-based education.

Enough buzzwords? I can add more.

The reality of matter: STEM education requires a lot of effort. And the US schools discourage it. There is no need for any "dynamism" in school math, school students study stuff that hasn't changed in nearly 2 centuries by now.

Oh, do fuck off. The teach-to-test is FINE for math. In fact, it's the absolutely best way to teach it. It's just that the tests _themselves_ have the consistency of wet toilet paper. And since they keep showing just how bad the US education is, they keep getting even mushier: https://newsroom.collegeboard....

Bring gaokao to the US!

That's the press doing its usual lousy job of communicating science.

The predictions aren't absolute, they are sets of scenarios for which probabilities are calculated. The longer we drag our feet, the more the set of plausible outcomes narrows. Take Syria -- Syria was a wheat exporter in 1990, but since 2008 or so has been unable to grow enough wheat to feed itself because of climate change when it had become dependent upon imports from Russia and Ukraine. This was early enough that likely we could not have prevented it even if we heeded early warnings in the 1990s when the current scientific picture solidified. We're not going to lose the entire planet in one go, it's going to be one vulnerable population after another.

It may seem like the climate crisis has completely fizzled to you, living in a large, wealthy, and heretofore politically stable country, but it is catastrophic for the people who have got caught. That's how the climate crisis is going to unfold: the rich and comfortable will be able to adapt to the continually changing status quo by moving their financial assets and supply chains out of the way, although you may be paying more for coffee.

At this point it's a matter of degree; we can't avoid problems now like countries being destabilized by climate change and generating millions of refugees. The question is how fast and how big a problem we'll have.

It seems pretty plausible that sub-recreational doses of psychedelics could reduce anxiety, but we have to be mindful that anxiety evolved in our species for a reason. Like inflammation, it’s a natural and critically important protective process that gets out of control in modern lifestyles. It’s unpleasant but pharmaceutically banishing it could leave patients vulnerable.

One of the biggest risks psychedelic therapy will expose patients to are the therapists overseeing their treatment. Psychedelic therapy has an appalling track record of abuse by therapists, including both sexual and economic exploitation. Advocates for psychedelic therapy claim it will “open you up” and I think they’re absolutely correct. But there are other ways to say “open you up” that mean the same thing but set off alarm bells: becoming more suggestible and compliant for example. If the therapist uses psychedelics himself he may have “opened himself up” to some bad ideas about therapist-patient boundaries.

Likewise people microdosing to enhance creativity should exercise caution. Psychedelics absolutely can in some instances unlock creativity by turning down excessive self criticism, but those criitical facilities play an essential role in the parts of the creative process that come after coming up with out of the box ideas. Self reports of microdosing effectiveness should be taken cautiously, due to their potential negative impact on metacognition. Those might be like the drunk who feels more confident driving after a few drinks.

No doubt these drugs have tremendous potential to treat extreme crippling anxiety. They probably even have nootropic potential. But their beneficial effect s come by suppressing natural mental processes that serve important purposes, and the promising results we have come from self reports or clinical reports from advocate researchers. I’ve been following this because I’ve been interested in experimenting with psychedelics for years, but what I have learned has convinced me to hold off until there is evidence and protocols for safe use that would persuade a skeptic.