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Can electric cars on the highway emulate plane-to-plane refueling?

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Re: Can electric cars on the highway emulate plane-to-plane refueling?

#41

Post by dsfyu404ed »

ashtonkem wrote: post #31
willis936 wrote: post #27

Earlier quoted context omitted.

Trains are large and inflexible. Short of having a city-block resolution freight train network at every population center, you'll need something flexible for the last mile of delivery.

You’re misunderstanding. The only reason why you’d need on-road recharging for hypothetical autonomous semi trucks is if they’re regularly traveling outside the range of their batteries, which is probably in the 400-500mi range. In a well designed infrastructure system, that shouldn’t happen often. Instead the hops of hundreds of miles should be handled by trains, leaving semi trucks for the last dozens of miles from…

Adding an extra step (rail hub to short haul truck transition, potentially at both ends of the trip) adds cost. This cost is (and will be for the foreseeable future) less than having the less efficient semi-truck do the entire trip at least for the kinds of loads that are currently carried by semi-truck. JIT inventory systems also don't play nice with rail.

Re: Can electric cars on the highway emulate plane-to-plane refueling?

#43

Post by adav »

jstanley wrote: post #12
cheerlessbog wrote: post #10

Earlier quoted context omitted.

The idea is predicated on autonomous control and presumably the vehicles communicate in real time...they all brake together at the delta V of the least capable member.

The "real time" control loop between the sensor on one car and the brakes on the same car is much tighter than that between the sensor on this car and the brakes on another car and then feedback from the other car that braking has started. I don't actually know how long it takes between the computer deciding to brake and the car actually starting to slow down, but I expect you can't just throw out a message saying "I…

There could be some leeway to initiative braking on following cars quicker with control loop similar to existing emergency brake assist systems [1]. These currently apply the brakes quicker and more powerfully than a driver’s foot when the car thinks it’s in an emergency situation. The same signal could be sent to following cars by the time the driver sufficiently engages the pedal.

[1] https://en.wikipedia.org/wiki/Emergency_brake_assist

Re: Can electric cars on the highway emulate plane-to-plane refueling?

#44

Post by patall »

yingw787 wrote: post #35
patall wrote: post #26

Can anyone explain what happened to battery swapping. A few years ago there was this Tesla show where they swapped three cars in the time it took to refuel a normal ICE automotive. But after that nothing happened. I know it is difficult to handle when you do not own the battery but I would guess 90% of private long distance trips are return trips, so you could swap batteries at your trusted former gas station every 2…

Immediate concern for me would be safety. My impression is the battery pack provides a lot of the rigidity necessary to keep the car in one piece, and swapping the battery out introduces new hazards. There's also the concern about liability, whether the battery pack you're getting is as good as the one you're trading in (what if it's older and has a lower overall capacity), and how that might impact resale value. Thi…

That's why you would only use those for long distance trips and for everything else you would own that one old pack.

Rigidity could indeed be a problem but so has been gasoline safety. There would need to be standards but there are also standards for charging plugs so, it is not like this never happened before.

Re: Can electric cars on the highway emulate plane-to-plane refueling?

#45

Post by dumbfounder »

patall wrote: post #26

Can anyone explain what happened to battery swapping. A few years ago there was this Tesla show where they swapped three cars in the time it took to refuel a normal ICE automotive. But after that nothing happened. I know it is difficult to handle when you do not own the battery but I would guess 90% of private long distance trips are return trips, so you could swap batteries at your trusted former gas station every 2…

I am imagining a scenario where an autonomous vehicle zooms toward the car at high speed and then from underneath the car swaps out the batteries then zooms away.

Re: Can electric cars on the highway emulate plane-to-plane refueling?

#46

Post by Retric »

ravenstine wrote: post #38
matz1 wrote: post #34

Earlier quoted context omitted.

Probably the same reason why smartphone battery is not swappable. For various reason we don't have swappable smartphone battery even though it is technically much easier problem to solve.

What reason would that be? I always assumed that was because of the pursuit of slimmer phones and to discourage repair.

It’s also a more complex and expensive. Swapping cellphone batteries means you need to own another battery which few people did once capacity increased. With cellphones people that want a swappable battery can just get an external battery pack but most people can simply recharge daily.

Re: Can electric cars on the highway emulate plane-to-plane refueling?

#47

Post by njarboe »

ashtonkem wrote: post #22
willis936 wrote: post #21

Earlier quoted context omitted.

What about an autonomous semitruck that could run 24 hours a day except for unloading/reloading cargo, refueling, and maintenance?

Trains. The fact that long haul semi trucks are a thing is a failure of infrastructure. Edit: as some have pointed out, it’s more a failure of policy.

100 trucks running right up next to each other is a train. I could imagine train operators converting their right of ways to a system where each train car can be autonomous and can leave the train and track without disruption. As the train comes by an exit location (station), the cars that need to get off just come out of the train and leave while the train tightens up again for aerodynamic efficiency and continues on without even slowing down.

These single tracks could even allow individuals to run their own single/double cars on them if the track was not to crowded and premium price was paid. With automatic vehicles, a reality on such controlled tracks today, our current infrastructure for transportation is definitely a failure compared to what it could be.

Re: Can electric cars on the highway emulate plane-to-plane refueling?

#48

Post by patall »

NickM wrote: post #39
patall wrote: post #26

Can anyone explain what happened to battery swapping. A few years ago there was this Tesla show where they swapped three cars in the time it took to refuel a normal ICE automotive. But after that nothing happened. I know it is difficult to handle when you do not own the battery but I would guess 90% of private long distance trips are return trips, so you could swap batteries at your trusted former gas station every 2…

It was abandoned because fast charging stations keep improving, and are much simpler and cheaper to operate than battery swap stations. It's already at the point where you can take a 400-500 mile road trip in a Model 3 with maybe a single twenty minute charging stop, which is just not that much extra time, and most people like to take a short break every few hours anyway. I suspect Tesla knew this would probably happ…

I see, that actually makes sense. To bad most affordable cars actually operate in much lower ranges.

Re: Can electric cars on the highway emulate plane-to-plane refueling?

#49

Post by goodcanadian »

baltimore wrote: post #25
jccc wrote: post #9

Asking sincerely: Why should we not simply pull over to do this? Planes obviously are a different situation, but cars can easily just stop. While cool to imagine, it seems unnecessarily complicated and unsafe to do this in motion on the road. [Edit: The prof and his team are quite serious about it, so I assume there must be a reason and I'm actually curious what it might be.]

Because charging takes much longer than filling up with gas. If someone is willing to pay a premium for charging while driving to reduce total trip time, that's a business opportunity.

This is often said, but I am not so sure. Fast-charging takes somewhat longer than filling with gasoline/petrol, but I usually also want a bathroom and coffee break. I can easily do that while my car is charging. That is not really true while dispensing gasoline. It is not so obvious to me that I am losing out time-wise.

This is not idle speculation. I own an electric car. Furthermore, the vast majority of my charging occurs at home, over night. The total amount time I have saved by not having to visit gas stations for literally months is significant.

Re: Can electric cars on the highway emulate plane-to-plane refueling?

#50

Post by amirhirsch »

NickM wrote: post #39
patall wrote: post #26

Can anyone explain what happened to battery swapping. A few years ago there was this Tesla show where they swapped three cars in the time it took to refuel a normal ICE automotive. But after that nothing happened. I know it is difficult to handle when you do not own the battery but I would guess 90% of private long distance trips are return trips, so you could swap batteries at your trusted former gas station every 2…

It was abandoned because fast charging stations keep improving, and are much simpler and cheaper to operate than battery swap stations. It's already at the point where you can take a 400-500 mile road trip in a Model 3 with maybe a single twenty minute charging stop, which is just not that much extra time, and most people like to take a short break every few hours anyway. I suspect Tesla knew this would probably happ…

A car with a 40 mile range would be cheaper to buy, and a lot lighter so also more efficient. You could swap in a 400 mile battery when you actually need it.
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