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We got a BMW i3, it has a battery capacity of 33 kWh. Fully charging it in 5 minutes, as the article claims, would thus require a 400kW charger, assuming an unrealistic constant charging condition. With a nominal battery voltage of 360V that would be 1.1kA, which seems quite a challenge.

And that's a fairly tiny battery as far as electric cars go. A Tesla 3 with the new 82kWh battery pack would require over 1MW.

On a related note there was an article[1] in the news here just yesterday about how building the charging infrastructure is challenged by the fact that the cost of expanding local transformer stations has to be shared by those wanting the extra power, like say a gas station wanting to add EV charging stations. This cost can be quite high due to the power requirements.

[1]: https://www.nrk.no/norge/ma-ut-med-mer-enn-25-millioner-for-...

Among other issues, I think that you would melt/fry the battery, unless you could charge it inside a freezer or something like that.

Not an engineer so this is just me spitballing / getting nerdsniped, but for that kind of use case I can imagine a charging station that you have to drive the car over, with a solid chunky connector sticking up into the car. Any cabling would be underground, and it could be combined with providing cooling for both the cable and the battery itself.

That would be the fast charging option, for at home charging you'd have to use the regular slow plug.

For a 100kWh battery, you're taking 6MW of power to charge the battery to full in a minute. 6MW is a small nuclear reactor or a medium sized hydroelectric dam. I cannot imagine a charging station wired for that kind of power being drawn when charging, nor can I imagine a connector that would safely carry this power. It can be done "safely" in the million volt range, but you're not going to charge a battery(typically 400-800V) with that. Just for a "fun" calculation, 6MW at 800V is 7500 amps - the cable for it would be bigger and heavier than the car, if it's even possible at all. And then finally, I can't believe there really exists a battery that just wouldn't boil at those rates, nor that we could effectively cool it.

Batteries do exist that can charge that fast. Some RC car batteries are "60C" indicating they can do a full discharge in 1 minute.

To achieve that, substantial capacity and lifespan tradeoffs are made, and you're right that cooling becomes necessary.

7500 amps isn't 'bigger than car' territory either. If you're happy to have copper the thickness of your forearm it wouldn't melt at 7500 amps, even with simple air cooling. "Not melting" isn't quite the standard we're after, but shows that it isn't unachievable.

That's good to know - I was extrapolating from some 1000amp cables I had to work with, and those were already too big and heavy to move once you had any length of it at all.

>>Some RC car batteries are "60C" indicating they can do a full discharge in 1 minute.

I mean, plenty of batteries can discharge that quickly, but that isn't synonymous with them being able to charge that fast, no? I can think of several examples of batteries, both Ni-Cd as well as Lithium which can be safely discharged fully at very rapid speeds, but you can't(shouldn't?) charge them that quickly.

Ugh, you poor people need to get your own hydro dam - simple.

In all seriousness, its hard for people to understand the values required and how scary those numbers in reality are.

Petrol is great source of energy as it relatively non-violent, only compressed and combusted it will explode.

Batteries on the other side are outright terrifying. Google people stabbing their phone batteries and see how violently they discharge. Scale that 4000mAh phone battery to the electric car.

I would be terrified if something went wrong with charging station that could do a under 10mins charges. Materials getting older a crack in insulation and you are toasted.

Just to nitpick your numbers a bit. 6MW, while a lot of power, is still a lot less than your average nuclear reactor, even a small one (The reactors on the French aircraft carrier Charles de Gaulle are 150MW each), and Hydro schemes are often in the thousands of MW.

In fact, many single offshore wind turbines are capable of generating a lot more than 6MW. GW's Haliade-X tubines have an output of 13MW each.

I was going off of the fact that at least here in the UK more than half of all hydroelectric power dams are less than 6MW[0], actually closer to 1MW than 6MW, and for nuclear power the Bilibiono power station operates 11MW reactors[1]

[0] https://en.wikipedia.org/wiki/Hydroelectricity_in_the_United...

[1] https://en.wikipedia.org/wiki/EGP-6

I've seen prototype "cables" designed to handle up to 800 volts at 100 amps for EV DC charging. In fact I had to carry a sample (just the cable and plug on the EV side, other end was open) a few meters and oh boy, I can still feel my shoulder and back just thinking about that. No idea how any regular everyday consumer is supposed to handle that. And that was even without any cooling liquid pumped inside which you'd probably have in the live application.

That's 80 kilowatts. To 'charge' a big gasoline truck, you'd put in say 20 gallons, which if done via electricity in 1 minute would be 57 megawatts, nearly 1000x more.

A gallon of gasoline is around 33kWh of energy. 33.41kWh*20/1min = 40MW

Diesel might be closer to 50MW? But regardless, it's not 33kWh per gallon of energy to the wheels. Most of the energy is wasted. So of course a battery electric truck wouldn't require that much energy to do the same work.

I've seen that trucks and buses just use multiple charging cables. But yeah, you'll never charge a large truck from 0 to 100% in 1 minute. Overnight charging will be the norm.

Yes, that was my point: Even cables that are already in the realm of "too big/bulky to be handled" don't come anywhere close.

These cables continue to surprise me, I remember prototypes for robotic “hands off” fuel pumps for petrol/gas that were being built in the 90s. With the rise of the standards around charging electric cars, it seems like a no brainer to standardise on robotics to handle the hook up as we go to higher power levels.

Park car roughly in the correct place, and wait. No more issues using any cable technology that’s appropriate like coolants or the sheer cable mass in terms of copper. The robot can be built to match , and every charging port makes a nice standard looking target for vision tracking and alignment to drive the robot to the right place every time.

That's what I was thinking. And with autopilot type systems the car could line it self up to the cable. The major downside is that this might increase vendor lock-in for recharging stations.

That is where legislation could come in.

This seems to be a great idea actually. An ISO standard cable with several tiers or power delivery ratings, mandatory for all EVs to accept should be the way to go. We have a standard gas/diesel "plugs" all over the world, why not have the same with EVs?

Edit: Obviously, a car should accept only the "tiers" that it is rated for, but the charging station and the car can negotiate which "tier" that they would like to charge.

Why not just standardize the height of the charging port? You can then just put the plug on a movable stand. No robots needed.

This is what I mean by "movable stand": https://www.slimlinewarehouse.com.au/movable-lcd-tv-stand/tv...

What about using very high voltage like 100kV? All the heavy parts could be in the vehicle and the charging station.

I did find this using 13 kV: https://www.energytrend.com/news/20180904-12449.html

What material will you make the insulators from? Will the insulation itself not be too heavy?

How about these:

https://www.schleich.com/en/product/high-voltage-cables-en/

100 kV DC, outer diameter 14 mm

Now that's the kind of thing. How many amps will that center core take (presumably not enough as is), and how might we modify that design to take more amps?

14mm is perhaps even smaller and lighter than needed for this application too - how might you expect diameter/weight to scale for cables over 100kV?

The plugs are rated for 5A so lets say that; 2.2mm core is overkill.

10kV is 5mm, 65kV is 10mm, so something like sqrt(V) + 4mm. I guess 500 kV would be around 30mm for each wire, which is starting to get unwieldy.

Not an electrical engineer.

Why not inductive charging or any other wireless technology? Also it does not require a single entry point - do it in parallel.

Also when 1 minute is not possible, how about increasing the time?

Edit: in addition, charging entry does not have to be on the side, it can be on top or on bottom - we do not need any gravity assist.

Wireless charging doesn't solve anything - you would still need to deliver 100kWh(for a large car battery) into the charging pad within a minute. And then you need to receive it on the other end - you don't have a plug, but obviously your receiver now has the same issue. You just moved where the problem is. I'd argue that having such an incredibly strong inductive field is a problem as well, but yeah, you're not even going to get that far.

Parallel charging is potentially the answer - but even with 10 cables, for a 100kWh battery, you're still talking.....600kW per cable? CCS goes only up to 200kW(and those are THICK cables), so if you increase the charging speed to 3 minutes then yes, you could do it with 10 cables. 6 minutes with 5 cables, 30 minutes with one cable.....and we're(almost) back to what existing technology already allows?

The issue is that with current plug placement there must be a really hefty cable inside the car too.

What about short range inductive charging from the bellow of the car (where the battery is)? With grid of 5x5 or 6x6 for example?

Inductive charging because it would be very difficult to have any kind of plug below the car because of the high corrosion risk.

Charger must align itself automatically to the right position and distance.

Inductive chargers are ~80% efficient, compared to cables which are well over 99% efficient. Even though super efficient and despite electrical conductors being good heat conductors, the cable still needs active cooling to dump waste heat. Your inductive charger and the attached vehicle are going to have dump tens of kWh of heat in a few minutes, and will have to do it through air, without barbecuing the humans inside.

Parallel charging is the current answer.

https://insideevs.com/photo/5439695/mine-smart-ferry-fast-ch...