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Comment by gameswithgo | Hacker News Reader

It is promising that a 5x increase is even theoretically possible. If one day even a 3x improvement became mass produceable that would be enough to make electric vehicles viable for all the use cases it isn’t currently that I can think of. Long range towing, extreme cold, track days, road trips with bikes and luggage strapped to your car etc

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An alternate line of thought - do we need Electric vehicles to do all that? If we could reliably transition mass of passenger transport and daily commute options to electricity, that alone could crack the deal. We needn't eliminate fossil fuel driven systems completely. It can still have some use cases, which on a planet scale could be made viable through a select oil extraction infrastructure across the globe. A scaled down fossil fuel economy with electric replacing mass of private and commercial vehicle use looks like the most likely scenario for the future, imho.

Absolutely the approach that is needed: net zero, not zero. We cannot completely decarbonize the long tail of fossil fuel uses - but we can create a mostly renewable energy mix. It is unlikely that air and space travel for instance will ever be decarbonized - but net emissions can be reduced or eliminated. The same goes for manufacturing processes and materials science. It's not an all or nothing proposition.

I think fossil fuels are enough of an ideological rallying point that they're going to be targeted no matter how niche and justified their use is (see also: asbestos). We're likely to wind up with plat based synthetic fuels in those use cases to make the ideologues happy (see also: Brazil, though they use synthetic fuels for a different reason) even if that's not the best/cheapest way to make those use cases net zero.

> even if that's not the best/cheapest way to make those use cases net zero

It's likely to be for the foreseeable future given that net zero otherwise requires carbon capture equal to the extracted fossil fuels, and we seem to be some way off effective carbon capture let alone cost effective carbon capture.

Keep in mind that 10% of the worlds carbon emissions is tarmac/roads. Not building, just them being around.

So mass transit does more lift than EVs in terms of carbon neutrality. Not to mention noise pollution and tire particulates causing asthma.

So with a capacity of 1k cycles and recharging on weekdays only, the battery should last about 4 years?

Is that enough to make electric cars viable for all use cases? It depends on cost --- of the car initially and of a battery replacement. It would have to be less than the cost of current electric vehicles which have a much longer expected battery lifetime.

You wouldn’t be charging from 0-100% every day though. For most people it would be more like 1-2 cycles per week, if not less.

It's hard to say what "most people" will do.

My wife plugs her phone in every night as a matter of habit --- just to be sure, whether it really needs charging or not. I know from experience that this degrades the battery lifetime.

Any battery that has an even moderately intelligent chip moderating its charge will round-robin the individual cells so that it’s not the same cells being charged/discharged all the time.

If you’re always topping off the charge at night, the cells in the battery pack are still experiencing full discharge cycles eventually. (Cells will end up staying at 100% charge for a while though, which is probably ultimately bad for them, but they should still be fully discharged/charged eventually…)

A phone doesn't have a thermal management system that can cool and heat the battery if required. Charging your car every day is not an issue.

Charging the phone from 60% to 100% is 0.4 cycles. So your wife is putting less than 3 cycles per week on the phone battery. Sitting at 100% does degrade the battery, especially since the phones all charge to 4.4V these days. I root my phones so I can set a 4.1V charge limit.

iPhones do have logic in software now to hold off on charging above 80% until the user is expected to take it off the charger [1]. Probably still not as good as personally optimizing your charge time based on battery level, but it's at least not quite as bad to be plugging it in every night as it used to be.

[1] https://support.apple.com/en-us/HT210512

Samsung phones on Android 12 have a toggle for "charge to 85%" now. Not as "smart", but a great way to extend battery life if that's your focus. That last 15-20% charge is apparently a killer.

It'd work for me. I'd absolutely trade long battery life to only ever using 80% of the battery for pretty much all my electronics.

Yeah, I was happy to toggle that option on.

I babied my iPhone 12 Pro by using an automation to turn off a smart-outlet at 76% charge. After a year I'm at 95% health, basically on par with everyone else.

I've discontinued the automation and will just buy a new battery in another year or two instead. /shrug

I would say its even smarter. I don't want to charge my phone to 100% every day, and I don't want to babysit it.

Smart charging would be: "start charging now and finish at time my alarm is set, while reaching 80% battery." Slow charging to 80% and your battery can last multiple times what it would "normally". I don't understand the craze for 40-60-100 watt phone chargers...

My four year old Sony phone does this, and the battery still lasts around two days, just like when it was new.

Sony you say.. now that's a brand that haven't p*ssed me off so far, or I don't remember.. Maybe I should consider them when Ill be searching for new phone, thanks.

That isn’t usually how “cycles” works out, no, unless you deplete the battery completely every day.

I know from experience that a lot of people will recharge every day --- just to be sure.

How this will impact their definition of "cycle" is unknown but again; based on my experience with batteries, it won't be good.

I think you may be misunderstanding the meaning of "cycle".

Charging every night for a 5 day week, from 80% to 100% is 1 cycle (in this crude example).

A cycle is not the number of times you plug in a battery to charge, it's a single charge/discharge full to empty and vice versa.

There is more to it of course because you never really "empty" a lithium battery, and for longevity it may be configured to never be fully charged to 100%, but that's roughly the point.

There is more to it of course ...

Yes, most rechargeable batteries will degrade over time just sitting there --- without any "cycling".

The article says it's a ten-year lifespan. Which seems reasonable since ideally, if it's a thousand cycles and a thousand miles per cycle, that's a million mile battery.

99% of commutes are less than 200 miles. Current car batteries support large numbers of charge cycles and have a capacity that's high enough for these trips.

However, many drivers do a bunch of 500+ miles drives per year; 1, 10, or 100, depends on the driver.

At 500+ miles, battery anxiety starts to kick in.

An electric car that combines current high-cycles-low-range batteries with a smaller low-cycle-very-large-range battery for those 10 500+ miles trips per year would be a killer product. We are talking here 1000+ miles without charging, which is kind of much farther than what most cars can get without re-fueling.

I do maybe one 500+ miles trip per month. That'd be ~24 cycles / year, such that these batteries would have a lifetime for my use of ~40+ years. That's more than enough for me.

There are a bunch of companies working on hybrid battery designs that combine different technologies to serve different purposes. Some of them are already hitting 800+ miles in real-world tests.

The tricky part is the recharging.

The car can't possibly know if the owner is planning a 500 mile trip the next day. The only "safe" approach is to assume they are and top up all batteries every time it is plugged in.

If the owner plugs it in every day, how does this impact the usable life of this new battery?

The car doesn't necessarily have to know that someone is planning a 500 mile trip, the car operator can tell it to top up overnight when necessary.

<i>...the car operator can tell it to top up overnight when necessary.</i>

The car operator may not always know when it's necessary --- assuming he is not psychic. He may just top up to be on the safe side.

* With lithium ion you don't want to sit at 100% all of the time, but it is fine to always keep it topped off to ~80% or so. Topping it off daily is good.

* If you are someone who doesn't want to worry about not going to 100% all of the time the new iron based batteries (featured in base model 3 right now for instance) don't care, you can let those sit at 100%, and they are safer too. The downside is less total range range and/or more weight.

With lithium ion you don't want to sit at 100% all of the time ...

Someone who drives infrequently (a senior for example) or has multiple cars could easily leave a car plugged in for days.

Sure, but Tesla recommends charging to 90% for daily use (except for LFP batteries), personally I charge to 85% to help increase battery life.

It also helps the battery when it gets cold, the car will use power to help keep battery warm, which also helps increase battery life.

GM in their Volt and Bolt holds back a percentage of the battery capacity so that at 100% of charge the battery pack is only charging to 85-90% and when it discharges to 0% the pack is actually not at zero. They do this to limit stress on the cells and to ensure longer service life for the battery pack.

How much possibility? Like once per a decade? Edge case could be ignored by patience at charging station or rent a car.

What could possibly require you to take an unexpected 500 mile trip at short notice?

And without the opportunity to charge at a supercharger on the way?

> At 500+ miles, battery anxiety starts to kick in.

I have a Tesla model 3, it's got a decent nav system, is aware of the battery state, current trip, average speed and the like. For me it makes range anxiety a non-issue. I had a 1200 mile road trip, did no preplanning, just filled the car with luggage and family, hit nav, and said "navigate to <1200 mile distant city>".

The Tesla experience is pretty transparent and the superchargers are pretty frequent and reliable. I've yet (over 30k miles) expected to charge at a supercharger and not been able to.

Generally I had more than one place I could stop and once charging it would give feedback like "charge x minutes to reach next charging station with 15% battery left". Sometimes we'd charge a bit extra waiting on someone and it would automatically pick a further charging station. While driving the car would helpfully say things like "You'll arrive at the next charging station with 15% battery left if you keep under 75 mph". Despite going through of some of the lowest density charging areas like eastern Nevada or southern Wyoming I had no issues.

The charging stations I used were quite close to the major highways, and the strategy we used was to fill up to 50-75% and recharge when we had 10-20% left. This involves more stops, but also maximized charge speed, often 550 miles/hour or more. Charging slows as the battery gets more full. With 3 people and a dog the car was generally ready for departure about as quickly as the rest of us.

I did however carry power adapters for 120v, 220v, and the popular J1772 just in case, haven't used them, except when it's free like at some Universities (like Stanford) or businesses (like 2 hours free at Target).

When you are talking about super chargers, are you extrapolating to the whole planet earth? Or have you actually driven your Tesla across all 5 continents ?

That would depend on the definition of a "cycle." If these truly enable 5x energy density there would be cars on the market with 1,200 - 1,500 mile range. The average American drives 40 miles per day.

If I were an average American driving an average amount and I charged my car every night it would be topping the battery from 97% to 100%. Does that qualify as a cycle? I don't know, but I doubt it. Even if I recharged once per week that would be 80% to 100%, and I would also doubt that qualifies as a cycle.

The authors estimated 10 year lifespan but I'm not sure how they came up with that number, either. If these batteries really do offer 5x density I would likely charge my car 30-40 times per year.

5x energy density (is that what this article is about? Kind of unclear to me) would mean a whole lot more than just longer range EVs. Thinking electric personal jetpacks, VTOL aircraft, etc.

True, but improvement on what? There's, let's say, doubling capacity (without doubling mass), doubling performance (discharge, without fire hazard), doubling how long it can hold a charge (without doubling thermals), doubling longevity (without doubling down on hazard materials)... Just of top of my head. Chemistry is hard, looks like it. What's the average doubling of any of these factors we've seen over the years? 10-20 years?

Energy density has at least doubled in the last 20 years. See figure 8 in [1].

And it's easy to overlook the most important factor for general applications - price - where the declines are much more dramatic.

People complain about the lack of progress with batteries but we've observed that EV range has doubled in 8 years. I see no reason that range wouldn't double again in the next 8 years - and I see plenty of reasons for that to happen.

[1] https://pubs.rsc.org/en/content/articlehtml/2021/ee/d0ee0268...

Indeed. The first Nissan Leaf had a 20 kwh battery in 2010. The latest model you can get in a 40kwh and a 60kwh variant. And you can upgrade the battery in that original one with a 40kwh one that is a drop in replacement for the original one. The next ten years are going to be interesting. Assuming nothing will change seems more foolish than most other predictions. IMHO 2x capacity improvement is pretty much a done deal. There are multiple viable paths; it's just a matter of building and scaling production for this. 4x is very likely and 8x not unimaginable. More a question of when than if. 8x is probably going to take a while.

and aviation beyond air-taxis

right!

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