Comment by toss1 | Hacker News Reader

Comment by toss1 | Hacker News Reader

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It should be relatively straightforward to imagine — we already have that in gasoline-powered internal combustion engines.

The Watt-hours per kilogram of good Lithium Ion batteries is around 250-280 Wh/Kg; for Lithium Iron Phosphate it's about 180 Wh/kg, and for Sodium-Ion about 170 Wh/Kg.

The raw energy in gasoline is about 12,300 Wh/Kg but automobile internal combustion engines get only about 20-30% efficiency yielding about 2500-3600 Wh/Kg. For aviation piston engines it is a bit better at 25-30$ so 3000-3600 Wh/kg.

So, the batteries, instead of being 10-12X the weight of the gasoline for the same net driving/flying range, could weigh about the same as the gasoline. So, a typical car with maybe a 16 gallon tank and 30 miles per gallon fills up with 128 pounds (58 kg) of gasoline to get 480 miles of range. The Li-Ion battery for that range would weigh something like 1300 Lbs (590 kg). That is a substantial additional weight for a car that could be 2800-3800 Lbs in ICE configuration, so 35-45% added weight (a bit less because of savings on the ICE engine, etc). This requires everything else to also be heavier, from the structural frame, the suspension system, and even the wheels and tires (which is also unsprung weight, further impairing performance).

With a 130Lb/60kg battery instead, and saving the weight of the ICE engine and fuel system, the overall car design could go much more lightweight, regaining a lot of performance and range, all while gaining the huge torque of electric motors.

In aviation, a battery systems of that weight would enable all-electric aviation to go from small performance niches to the default for general aviation.

So yes, it would be a HUGE benefit to achieve 10X energy density batteries, and we do have reference points for people to imagine it.

> With a 130Lb/60kg battery instead, and saving the weight of the ICE engine and fuel system, the overall car design could go much more lightweight, regaining a lot of performance and range, all while gaining the huge torque of electric motors.

I think you're underselling it, even. A typical like-for-like modern EV is only marginally heavier than the ICE equivalent. If we were able to drop the weight of the battery by a thousand pounds, cars would be lighter than they have been in decades while retaining all the modern safety and convenience features we've come to expect. And if density improved along with weight, we could make EVs with the same form factor as today but with over a thousand miles of range. Not that we need that, but it is just as a tiny example of how mind boggling the game change would be.

As it is I've only recently internalized the notion that the most powerful electric tools are battery powered (what can I say, I grew up when rechargeable batteries were NiCad and they basically sucked). And it will just get better and better as time goes on.

Some people might need that range. If you cannot charge at home and you don't have good public charging infrastructure then you might want enough range so you only have to deal with charging once or twice a month.

If you can't charge at home it's probably because you're in an apartment, which means you're in a city, in which case there's going to be charging infrastructure.

Yes, underselling a bit for sure! I didn't even want to get into the optimizations available if cars were really designed for lightweight when the entire motors+battery is only 100-150kg, and the battery can be low and centered.

We could go for performance, trading off some battery for four inboard motors (fully sprung weight) with half-shafts and CV joints, steel space-frame chassis and carbon fiber body — it could put many supercars to shame.

Going for range, same light-weighting, but less powerful motors and adding more battery, the range could get silly long at something like 1000 miles for 100kg of battery.

For the kind of long range options another poster mentioned, with 100 kg for 1000 miles, a few 10-kilo swappable battery packs could make it easy to trade luggage space for range, or bring them to a charge station only occasionally, but not lug them around for most in-town trips.

No question, we could go wild!

> 10-kilo swappable battery packs

I like the way you think. Putting a meaningful amount of capacity in something luggable by an average human would open up a lot of possibilities. Not just for cars, but everything. Our battery powered future looks bright already, but this would be incredible.

> we could make EVs with the same form factor as today but with over a thousand miles of range. Not that we need that

I think this is the way to go. For most people (you can never please everyone) 1000 miles is enough to cover a full day car trip.

Then 8 hours of charge time while you sleep.

Charging while you sleep requires more distributed, lower power infrastructure compared to a 10 berth service station trying to juice cars in 5 minutes as seems to be commonly touted. I haven't run the numbers but juicing 10 cars in 5 minutes has to require significant electrical infrastructure!

Side bonus: never having to go to a service station.

> juicing 10 cars in 5 minutes has to require significant electrical infrastructure!

I believe it is becoming fairly common to use batteries as a buffer at fast chargers. The demand charges for bursting megawatts of power from the grid are apparently really steep, so it makes sense to put in a big battery and steadily draw a lower amount of power and then just charge cars from the battery.

An EV doesn't need to have 480 miles of range. Nobody is driving that distance daily. 98% of trips are under 50 miles. Only 0.8% of the trips are over 100 miles!

Also, EVs use regenerative braking. That should help a little bit.

EVs should be built with 100 - 150 mile range. All families with 2 cars can immediately switch one of their cars to a daily driver EV and the other vehicle is a minivan. There are lots and lots of people for whom an EV works perfectly well and if they need to go longer, US has a robust rental car industry. What would help is to let people charge anywhere they park. All workplaces should offer free charging, and companies can negotiate to get paid for charging their employees cars. The price of electricity goes negative because of lack of demand, and this is something that they can offer to the grid, demand as a service.

> EVs should be built with 100 - 150 mile range. [..] if they need to go longer, US has a robust rental car industry

As an EV owner myself, no. Absolutely not.

The reason is simple: The mere existence of low-range EVs hurts overall EV adoption, because people aren't going to rent a car just for a road trip. You're talking about adding $100+ per day on what's supposed to be a cheaper method of travel compared to flying.

ICE-holes don't think critically. They don't care that long range EVs exist. They'll just see one that only gets 100-150 miles of range and go "See? EVs have short range. They're not appropriate for road trips. That's why I'll never get one.", despite plenty of 250+ mile options.

Now, I suppose you could argue that this type of person would simply never get an EV and would just come up with a different reason, and you'd probably be right. But the general point still remains: People want a car that satisfies ALL their needs and won't settle for something that works "only" 98% of the time.

"The reason is simple: The mere existence of low-range EVs hurts overall EV adoption, because people aren't going to rent a car just for a road trip. You're talking about adding $100+ per day on what's supposed to be a cheaper method of travel compared to flying."

Just wait for people to be priced out of ICE cars. EV's should be and will be significantly cheaper to buy and manufacture.

Not only that, but with a longer range, you have more flexibility in planning recharging. It may take more time to top up from 50 km left to 500 km, but you have more flexibility about when to do it. Something that needs a daily charge is going to be interfering with your schedule.

Exactly.

Having only a 100 mile range is plenty for your daily driving, but if you can't charge at home, it becomes very disruptive.

Short range EVs typically only support J-1772 which only charges at up to 19.2 kW, and many cars only even support 11.5 kW. You'll be charging for at least an hour.

At least with a 300 mile range, most people could get away with charging for just 20 minutes/week.

>> 98% of trips are under 50 miles. Only 0.8% of the trips are over 100 miles!

Sure, ubiquitous charging will be enormously helpful to adoption, and universal rapid charging also. But the reality is it doesn't yet exist.

Until then, just because long trips are lower frequency does not mean they are less important or can be ignored as a requirement, particularly if a person/family has only one vehicle.

The long trips may be the most important trips, maybe to see family only a few times a year...

Plus, even though you might be able to rationalized away the long range requirement, generations of people are accustomed to cars yielding 4-600 miles between fill-ups. It is not only the ability to drive on a long trip, but also the need to only fill up your car every 1-3 weeks instead of every day or two.

Desirable Range between fill-ups is also a human-factors issue. You want the range of the car to be at least, indeed around, the distance people can drive in a single stint. If you can drive 350 miles in 4.5 hours, and your car gets that distance, you're probably OK resting and filling up. If it goes 1000 miles between fill-ups, that isn't a big advantage. But if the car makes you stop before you feel you need to stop, that will feel like the car is not good enough for your needs.

So, sure, if we suddenly got 2500 Wh/kg batteries and could easily make cars with a 1000-mile range, and manufacturers offered 1000, 500, and 100-mile ranges, I'd expect the most sales to be in the 500-mile units.

If we stop considering ICE , its still a whole new world would created by smaller batteries .

could be some bad examples(right now in mind),correct me . but smart ring , BCI systems is not possible with oil.

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