New 2MW electric vehicle chargers could revolutionise mining industry | Hacker News Reader

New 2MW electric vehicle chargers could revolutionise mining industry

thedriven.io

84 pointsclouddrover132 comments

Mining is not the only place where this is starting to happen. Fully charged recently did an episode on an electric digger: https://www.youtube.com/watch?v=cumZxYjzx6M

Fuel cost is a great incentive of course but other advantages include a lot less noise and pollution; which is great for indoor operation. Also, these things only use power when you use them (as opposed to idling and slurping lots of diesel).

I could see batteries get common for a lot of equipment that is currently diesel powered, in the agricultural, construction, and other sectors. If all you need is a lot of torque/power, electric & hydrolic can do the job.

Electrical is also a lot simpler and cheaper to maintain.

it is also upgradeable - i.e. an improvement in efficiency for a motor of the same format, or improvements of the battery in the same format can both be "drop in" upgrades. Not necessarily trivial, but much easier than with ICEs.

Not only is it much cheaper to maintain, but also a lot safer for the work site and workers to maintain as well.

Used motor oil is some nasty stuff, and spilt coolant is quite toxic (but attracts animals).

With all the electronics driving these machines, I don't think they are simpler. There are certainly less moving parts, but if something fails in an electric version you will only be able to debug down to the modular level, which could be VERY expensive to replace. Also, if the manufacture goes bust, you may never be able to get a replacement module so the vehicle is now worthless.

Electronics have been running gas engines for decades, get over it.

You're describing every modern industrial vehicle, battery powered doesn't change that at all.

Oslo is planing to go zero emission on all it's construction sites. [1]

This charger could be handy for them too :)

[1] https://translate.google.com/translate?sl=no&tl=en&u=https%3...

Fascinating... I always thought that stuff would be the last to be electrified.

Not that surprising actually, the static models (ie a crane in a scrapyard) have been electric for a long time.

If anything, the biggest challenge / last bastion will be for the highly mobile operations, bringing all the needed infrastructure to power them, which isn't as much as problem with diesel.

Maybe we'll see trucks mounted with large arrays of batteries to deploy on the field.

ironically enough, there are more and more electric drilling rigs now, especially when drilling in-fill wells in established fields or near/in cities. they don't use battery power though, just temporary power lines and a mobile transformer skid.

I always thought they should be first. They are order of magnitude more utilised than passenger cars (at least 30% of time compared to 5% or so). They produce tons of noise and are more complex than electric.

It just hasn’t been cost effective until now. Tesla saw this and started with a very expensive roadster and just recently ended up with more affordable options like the Model 3.

Industrial equipment is either making money or spending it. I look forward to the cost optimization that will come with battery powered heavy machinery.

Thinking aloud: how can the electrical grid keep up? Surely we need to invest in this area, too.

The answer is in the hp per ton numbers for heavy equipment. The ratio's are a lot lower than passenger vehicles.

D6K tractor, ~30,000 lbs, but only 125 hp.

Tesla 3, 3500 lbs, and 260hp.

Worked at an open pit mine in the 90's...electric shovels. Cat had just come out with a diesel one when I was leaving. If you go huge electric is the only thing that will power it and the danger of fire from secondary forces like friction are greatly reduced. Friction provides the heat and you don't want a fuel source close.

The charging system being referred to is called HPCCV (High Power Charging for Commercial Vehicles), and is being defined by the CharIN group, the same industry organisation responsible for the CCS standard.

Incidentally, Tesla is also involved in this effort, as part of the specification of the charging connector for the Tesla Semi.

CharIN Steering Committee paves the way for the development of a CCS compliant plug for commercial vehicles with >2MW

https://www.charinev.org/news/news-detail-2018/news/charin-s...

I don't know who the big players are in electric busses, but I bet this is useful for that too.

Yes! Several electric bus makers like BYD, Proterra, and New Flyer are also members of CharIN.

It's nice to hear that Tesla is working on a real standard for once. I bought an EV recently, but didn't consider the Model 3 because it doesn't have a J1772 port (nor a proper dashboard, but I digress.)

For the model 3 - you need a small dongle for J1772 (provided).

On the other hand Europe pushed back on Tesla and its proprietary charging standard and cars there have SAE charging ports instead of tesla ports. (SAE ports are dual J1772 + fast charge)

I wholeheartedly agree with your dashboard complaint. Used Model S? Autopilot + big battery + dashboard.

Tesla comes with a J1772 adapter. Isn’t J1772 limited to 20kW?

Why would a built-in 20kW max charging connector be a must-have specification for an EV?

And the lack of the “real dashboard” is obviously one of the best things going for the Model 3. Makes night time driving in particular almost surreal.

The car is extremely forward thinking and futuristic. Definitely not for everyone.

> Why would a built-in 20kW max charging connector be a must-have specification for an EV?

The J1772+CCS DC connector can handle up to 350 kW, but even if that weren't the case, I would prioritize standardization over raw power. I don't want a car with a proprietary dongle for J1772, nor a phone with a proprietary dongle for USB.

Proprietary connectors and anti-consumer and anti-competition. It would be nice if more people said no to them.

You will have to try pretty hard to convince people that using a small adapter IS THE END OF THE GODDAMNED WORLD.

Just to put in perspective if my math's right based on 139k btu per gallon and say 40% diesel engine efficiency and 60 gallons per minute truck stop diesel pump flow, the diesel pump is equivalent to about a 60 megawatt charger.

Which is why a diesel semi can refill in a few minutes and go for 1000+ miles while an electric semi will take half hour to charge for 500 miles at 2MW.

Obviously though for mining operations where its short range goes up and then back down electrification is perfect, its also great for urban buses with regular short routes.

Apparently the largest electric mining trucks on earth never have to charge. They go up the hill empty, load up with tons of rock, and regen all the way back down which is more than enough to recharge. This makes my engineer's heart smile.

Yes that is a beautiful application of regenerative braking I have to say.

Here I was thinking stuff was loaded down in the mine and then driven UP out of the mine.

I realize there are differnt kinds of mines, but assuming it's a hole in the ground, the truck takes the material up, and the hole isn't situated on a hill... why and where is it going down with material? Really interested to read about this.

Probably meant to write a quarry rather than a mine. I think GP was talking about edumper[1]

https://www.autoblog.com/2019/08/26/edumper-electric-mining-...

Ok " drives up a 13-percent incline to pick up the 65 tons of lime and marl it needs to bring to a nearby cement factor"

It was a particular scenario where the quarry was uphill from a factory. Most mines and quarries probably don't have that possibility (They are both holes).

Many quarries are on mountains and this is not an uncommon scenario.

more details about that particular truck: https://hackaday.com/2019/08/22/electric-dump-truck-produces...

> Apparently the largest electric mining trucks on earth never have to charge.

Well that can't be true.

Yes. Yes it can. Regenerative braking downhill, while holding a full load, can generate more power than it takes to move the empty truck back up.

> Well that can't be true.

Think it through a bit more, there isn't any physics being broken here, because the load (i.e. mass) only travels one way.

Those trucks still have to plug in though but to discharge. Regen breaking stops working when the battery is full.

With a big enough hill, you could use the excess energy to smelt the ore on the way down.

The key to sustainability is to organize manufacturing across large height differentials. I’d better open some mines in Denver.

The mines are located at the top of a hill? I tend to think of mines as being down underground. Are we talking about strip mining here?

in that case, top of the hill compared to where to material needs to go, which is at the foot of the mountain.

Similar stuff happens in a ore mine in Sweden with freight trains going downhill to the coast from the mine.

https://www.schaeffler-tomorrow.com/tomorrow/76/index.html

Commercial vehicles are in a position of advantage here. Many of the places they visit are industrial in nature and those will already have large power hookups. Using the loading/unloading time to charge would seem to be an obvious thing to do.

Some entrepreneurs in Adelaide recently developed a fully electric utility vehicle for use in agribusiness and mining. It's based on a 79 series LandCruiser (which are still made brand new) and it has 350km of range. I saw some people scoff at that, but mining and agribusiness have the ability to introduce infrastructure, and these vehicles are work vehicles for use on site. Well managed vehicle and battery stocks could see these running 24/7 if need be. Have some solar on site or a grid hookup and you'd never have to worry about fuel logistics for the light vehicle section of your fleet.

https://thedriven.io/2019/10/24/first-electric-ute-engineere...

Electric vehicles also come with an enormous low speed torque simply because of the nature of electric engines.

This is why mining haul trucks use them for brakes.

A quick thought experiment...

If you wanted to transfer 2MW, you could do it at 200 amps and 10,000 volts.

Two 200 amp conductors, 3 meters long, and 10 mm^2 cross sectional area will come out at half a kilogram. 400 watts of heating will happen in the wire, which could be cooled by a 1mm^2 water/steam return cooling pipe in each conductor running at 1 ml/sec. That weighs another 12 grams.

Insulating a 10,000 volt supply sounds a lot, but if the wire was insulated with PTFE, with a 10x safety margin, you would only need a thickness of 1mm on each conductor. Total weight 140 grams.

So - the total weight of a 2 Megawatt human-safe cable could, with the right engineering, be under a kilogram (2 lbs) for 3 meters of cable, plenty to hook up your car or truck.

You're not wrong, but what is an EV going to do with 10,000 volts? You'd have to convert that into something useful to the battery system, so all you've done is shove the efficiency drop and heating issues into the vehicle's on-board transformer systems (which would add more weight) instead of the charger.

> “If we increase the voltage on the car side then we can reduce the current we need to push through the cable….so we are looking at higher voltage drivetrains,” says Elshout.

Presumably connect the batteries in series rather than parallel, so that the voltage is increased and the current is lessened

It isn't unreasonable to have a battery which can reconfigure itself. It could switch from parallel to series just by opening and closing a few relays.

I'm thinking this would probably greatly increase the chance of arcing and catastrophic battery failures in the cell packs, but I'm not certain on that. Also, you still need to get that power into something useful for the rest of the car now - usually 12V for electronics and probably 350ish volts AC for the motor, so you're still going to need to deal with the conversions at some point.

There's a reason high-voltage lines are nowhere near people and transformers are chunky as hell. Probably those reasons overlap with EV design constraints.

It's entirely doable. Tesla packs are already close to 400V and it's totally possible to go much higher. Keep in mind that every battery is a resistor so the voltage across each one is still tiny, even if the overall series voltage is massive. The reason power transmission equipment looks so weird is A) because it handles 345,000V and B) we have a lot of it and the chunky transformers and bare, massively spaced out conductors are way cheaper than wrapping everything in teflon.

Also, pretty much all EVs have a 12v lead acid cell somewhere. It's kinda dumb but it's the cheapest solution to having 12v for relevant systems. The pack/charger voltage is stepped down to charge them.

Remember that OP said 10k volts. 400 isn't close to that.

For all the "move fast and break things" of Tesla, they haven't moved fast and electrocuted people with a 10k volt battery system.

Downconverting voltages is surprisingly easy - a single bank of MOSFETS and an inductor is all you need. A 2MW convertor made of [1] comes out to less than 100 grams (excluding cooling, but that's fairly small at ~100 watts).

There are also a lot of reasons to increase voltages in EV battery systems. The current ~400V systems need thick heavy internal wiring, and for all electric (ie. no mechanical) braking and ultra fast charging, they are insufficient.

[1]: http://www.ti.com/lit/ds/symlink/csd19537q3.pdf

Have you seen voltage rating on that thing?

You can't reliably handle 1500V+ voltages in solid state electronics without purpose made IGBTs, or exotic semiconductor materials.

Your EE knowledge doesn't seem to be more than cursory.

It has a maximum voltage rating of 100V, so you would need 100 in series, with leak resistors to prevent any one avalanching. This is how most modern high voltage switches work, because IGBT's are far less flexible.

Take apart a tesla Model 3 motor controller and let me know what you find...

To begin with, Tesla's "motor controller" is an inverter. The charger on board is AC-DC. DC-DC

It's an old, but still not completely solved problem: imagine your stack open, but for a single FET, and your resistor is a little bit off. It instantly pops, and the "tuning" for the rest of it is now completely off, and it will cascade further

In case of Tesla, they do use the exotic semiconductor materials I mentioned above. SiC goes to 1500V nominally

You need to learn electronics engineering beyond wiring Arduinos

There is old, but still quite good and relevant explanation why stacking FETs suck on edaboard https://www.edaboard.com/showthread.php?269261-Is-MOSFET-in-...

There is an even older, but still excellent paper published by Philips called "Power Semiconductor Applications" where they explored nearly all trick to make FET stacks to work reliably.

Short: it's near impossible to do it reliably with off the shelf part, and it's better to not to risk if you deal with 600A+ currents. And if are determined to do all tricks necessary, IGBTs or III-V materials will still win on simplicity and cost

People have taken apart the Tesla Model 3 inverter and we know what they've found. Here's a hint: it's not a stack of 100V MOSFETs in series.

Depending on the model (SR+, Performance, etc), it's either SiC MOSFETs or IGBTs. And there's only one in series, not 10 or 100.

Also, please do me a favor and never design power electronics ever...

You understand that the device you linked will blow up if exposed to over 100V right? You're insanely oversimplifying what it would take to convert 10kV down to a usable voltage for use in EVs. Anything that can convert 2MW will be the size of a fridge, at minimum. If you could save a bunch of copper cabling by running everything at 10kV, people would be doing it. 800V is already pushing the limits of what most folks can do with technology we have today.

As a reminder, 10kV can arc close to 2 inches in free air (depending on humidity, of course), which means you need to insulate the hell out of it anywhere it's exposed. That means motors are pretty complicated to use at 10kV. By comparison, 800V only arcs 0.1mm (0.004 inches) max.

Yes, and even a tiny penetration of the insulation will destroy the dialetric strength of the material, posing a substantial risk to humans.

Every step of your analysis is several orders of magnitude too optimistic. The only thing sensible here is conceptually going to higher voltage.

Loss in these systems is dominated by switching, not conduction. Are you just using the Rds(on) figure? It's best to work back from efficiency for back of napkin analysis. At 99 % efficiency (very optimistic for such a large step down ratio), it's 20 kW of loss, not 100 W. That's a lot of power to pull out.

(1) Rds(on) Cgs product for a 100 V FET is a lot better than a 10 kV SCR or IGBT.

(2) The inductor for a 10 kV, 2 MW converter will be massive, lossy, and hard to insulate.

(3) That MOSFET that can only handle a few 10's of W of dissipation before it melts off the PCB, even with forced air/water cooling.

Times like these remind me that when people speak so authoritatively on HN they're usually full of shit.

1 mm of PTFE on a 10 kV cable is not even remotely close to human safe. Nick the insulation on such a cable and you turn your user into a quickly expanding cloud of plasma. Cables for that sorts of voltages and currents come heavily armored for mechanical stability, not only dielectric strength.

A 100um thick layer of foil mid-way through the PTFE, together with capacitance testing between the conductor and the foil will allow software to detect any knicks before they get deep enough to do damage. Adds <5 grams to the weight. Also, any high voltage system would use a balanced +- non-ground-bonded (ie. floating) supply, so a human could touch one or other bare copper conductor without risk anyway.

Far more user and environmentally friendly than todays engineering approach of "just make the insulation really thick and weigh a ton while the electronics are dumb and wouldn't even notice if you hammered a nail through the conductor".

Feel free to develop a system that can provide high voltage cabling at a fraction of the cost of traditional methods if you think it's so easy. You'll have a boatload of money waiting for you.

Also, there's already plenty of electronics in most cabling setups for EVs that definitely WOULD notice if you ran a nail through the conductors. What you're proposing just isn't safe.

Others have commented on technical feasibility already, but I want to point out, this is not sitting in an office powering a smoothie machine. It will be in contact with dust, dirt, debris and tools, and angry people. Your 1 mm of insulation will not last a week.

Not to take away from your point, I know you weren't talking about mining, but it should be pointed out that in an active mine there would surely be at least 10mm of insulation to protect the cable from damage.

Yes, probably with all the problems that are highlighted in the comments below that I’m not going to repeat. This seems to me a serious over-engineering problem. Why they didn’t think to use the battery swap in probably one of the few use cases where it makes sense?

Are there any mines where machines/vehicles are powered by e.g. overhead cables? Seems like that might in some cases be cheaper to pull off than equipping huge vehicles that go up and down the same path over and over again with huge batteries.

Depends on what you're moving, I suppose. Some materials may have gasses that don't like sparks.

Unless your vehicles are operating a very consistent route that rarely or never changes, it's likely to be cheaper to go with batteries than to build and maintain a network of overhead wires.

The article mentions that pantographs are unusable due to the number of exposed moving parts and the existence of conductive dust.

Conductive dust is evil. Even your phone will likley stop working if you get conductive dust into it. It's as bad as water, except gravity doesn't keep it pooled on the floor.

I searched a bit and found that "Trolley Assist" apparently refers to a system where large diesel-electric mining trucks use overhead lines for part of their journey. (You can do an image search for "trolley assist" and find examples.)

I guess this is the kind of thing I was looking for.

There is an example of this at the Lumawan Copper Mine in Zambia. It's trucks are powered by overhead cables and electric motors whilst driving up the fixed ramps, It then switches to diesel when moving around away from the ramp. What is really interesting is that this not only reduces fuel use but allows them to move up the ramps much more quickly and improves productivity of the mine.

I don't think that would be suitable in an underground mine due to the risk of sparks igniting flammable gases. But for open pit mines it would be OK.

Kind of but not exactly. The electric shovels are actually plugged in with large electrical cables that are routed around the dig site with tractors.

Trucks themselves wouldn't really work too well with overhead methods though.

For what it’s worth I know the three highest costs in most mines are: Diesel, explosives, and tires. Anything you can do to address those issues are big $ savings

Tires? Really?

Most work vehicles rarely go above 10 mph, and could probably get away with non-air-filled tyres made of steel if necessary. They'd last forever then.

https://www.mining.com/kal-tire-at-minexpo/ seems to back that assertion up.

Pneumatic tires have far superior performance characteristics.

They have steel wheels. They are called sheep foot wheels or compaction wheels. They are much harder on the equipment running them.

They're 50-80k a tire on a cat797 and the truck has 6. Mine roads aren't the same as normal people roads, top layer can vary between what you see on a gravel road to basically really crap with chunks bigger than your fist. Add on to that you're carrying anywhere between 60 to 400 tons.

It's promising to see some other areas more than the cars trying to use electric vehicles. I hope we can reach a 100% electric (and clean generation) before it's too late...

It's already "too late" in the sense that stopping carbon emissions won't be enough to prevent catastrophic change. It's just now that in addiction to stopping, we need to go negative and start sequestering carbon. This is a far more expensive path than if we had decarbonized sooner.

For detailed info from real scientists rather than an internet rando, see IPCC SR 1.5, in particular figure 2.5:

https://www.ipcc.ch/sr15/graphics/#cid_457

And if you have kids or care about fairness to future generations, this paper should spur you into action:

Young people's burden: requirement of negative CO2 emissions

https://www.earth-syst-dynam.net/8/577/2017/

At some point isn’t it simpler and cheaper to have several independent battery packs which each present their own 350kW ports and you can connect multiple charging cables at once — versus inventing entirely new standards and needing a pluggable harness that can carry two freakin’ megawatts?

That's what Tesla showed for the semi, it's 4 car battery packs used in parallel to power 4 motors, and a 4-cable cable for charging.

It might be hard to independently charge parallel batteries - you'd have to electrically isolate them and re-connect them after charging, right?

Or would you have something like one battery per wheel or axle if you had multiple motors?

I'm not sure how much these batteries are compared to the rest of the truck but why not just have removable battery packs that can take longer to charge while a fresh one gets clipped on? You might only need a few % spare batteries?

It's difficult to build an interface for high power draw which is convenient enough that doesn't break down over thousands of uses.

I always thought mining equipment intentionally runs on hydraulic power (and pneumatic back in the day) to avoid sparks that could set off possible gas or dust particle explosion. With brushless motors etc I can imagine how electric can match the safety of hydraulic power, but lithium-ion batteries in a mine? That is a horrible accident waiting to happen. What if the battery is pierced by something? What if it shorts internally when due to an accident? I wouldn't want to be anywhere near it when that happens. We limit the size of lithium-ion batteries we can fly with precisely for the same reason.

Flight limits on lithium are because the TSA and NTSB can't control the quality of products shipped in luggage holds on passenger jets, not because lithium batteries can't be made safely. Also piercing a battery is a secondary concern to the primary hazard of an object piercing protected machinery. The heat from the lance could spark a fire, and you don't need a battery for that.

No. Unless its specialized underground mining may take precautions, but a huge portion of above ground mining equipment is already electric. Most of the biggest shovels on the planet are hooked to a power cable.

Interesting; it seems that the dust in mines is actually conductive, and makes for a challenge with high-powered appliances.

Any foreign material in high-powered electronics (conductive or not) can cause problems, so these electronics must always be sealed properly.

But I foresee no big problems with this, because this is something that manufacturers of such equipment have plenty of experience with.

I saw that too. I wondered whether it might be simpler to have removable batteries (I know they'd be big) and set the charger up on the surface, away from the conductive dust. Vehicle downtime that way may be shorter (remove expended batteries and replace them with a fresh set from the charging station) than charging the vehicle. Maybe that means you need fewer vehicles?

Not a fan of the class of comment where people from outside the field propose dumb obvious solutions that make no sense to any actual practitioner, so this is more of a question.

The problem with that is getting the batteries to surface. Underground mines operate in either of two access methods: shaft to surface or ramp to surface. In shaft to surface you use an elevator to move all the ore and waste out of the mine for processing, in ramp to surface you'll either use a conveyor belt or use trucks like these to run from where they're loaded to surface. Trucks are also used in shaft access to move ore internally but generally not to surface. In the truck to surface the swap would work but in a shaft access scenario you'd have to throw the batteries into the elevator which has an impact on the proportion of the time you use the shaft for ore. Also usually those trucks are left near where they're needed the operators get picked up at the end of their shift and the next guy gets dropped back at the equipment at the start of his shift. So positioning of these chargers would be tricky. The payoff in terms of savings in ventilation though are where the benefits come for these though. Price of electricity can be very high depending on where the mine is since it's very common to operate off grid in remote locations.

Thanks, I understand that. Of course access-to-surface is another constrained resource which is no doubt already optimized for existing operations.

Sounds too ambitious.

There are people working at 900kw chargers at BYD, and they say that cabling for it is already so stiff and heavy that it's bordering on the limit of what is humanly possible to handle.

Under spec electronic components are exploding in split second. Imagine a bank of DC-DC converters operating at 600A, and where few stages go out of sync. 10% of 600A is still 60A that turns into heat, in addition to heat already generated by normal operation.

In a mining situation, why would you think they’d be handled by humans? I would expect it to be a machine driven coupler. Completely unrealistic in a consumer situation due to potential damage and liability. But in a mine? Nobody is going to care about a scratched body panel.

They might care about horrific electrical accidents.

With High voltage/high Amperage acidents - your lucky if you die on the spot otherwise you last a few days in intensive care with limbs blown off and your internal organs destroyed

Mines are such dangerous places that horrific electrical accidents may happen occasionally and it's still an improvement from the current situation.

I think the end goal is to not have humans on the field unless something untoward happens.

You can couple mechanically, but get a human to check before actually supplying power. Seems like a simple thing to fix.

Like EV chargers, the couplers and protocols are designed with safety in mind. It's not like you're plugging in to a giant electrical socket and throwing a switch. The system handshakes, runs tests for current leakage, etc. If anything doesn't check out 100%, it won't energise.

Have you not heard of murphy's law, or not thought that miners might take shortcuts and bodge a connection.

Then where are all the folks dying today from the high power Tesla Supercharger incidents? 2MW or 250kW, either way you'll be dead if that accidentally lights you up.

If you set the system up right, you can't do that in a meaningful way, and if you do... well there's 2MW of deterrent. It only takes one workplace incident like that to make sure the bosses put some measures in place to make sure it never happens again. And keep in mind: at that kind of power level, you aren't just zapping one person... it's probably going to destroy a LOT of equipment and infrastructure... so there's a hefty monetary incentive to make sure that never happens.

Consumer EV charging is basically a cooker circuit.

When you go to serious Amperage and High/Medium Voltages its a completely different ball game.

Sure, the wall chargers you have in your house are. You think the 400V, 625A circuits (250kW chargers) are just dumb circuits though? Fairly certain they have temperature and voltage monitoring on both sides of the cable and both sides of the connector, all to monitor for any issues with either the connector or the cable continuously. Anything goes wrong, gets to hot, etc? It kills power.

You're right though. Medium voltage circuits (and above) are going to be much more complex. The fact is, once you start operating at medium voltage and above, stuff that previously was an insulator may not actually be as insulating as you think...

They use these kinds of automatic couplers for the electric ferries here in Norway: https://youtu.be/epOAE8pudsg

> "Sounds too ambitious."

Perhaps I'm naive, but I believe ABB know what they're doing when it comes to high power electrical systems. These guys build AC-DC converters in the range of several gigawatts for HVDC links.

I used to do some welding with a stick welder with 100 feet of 4/0 gauge copper welding cable. Super heavy to drag around and very difficult to wind up. And that was for a few kW. So these 2MW cables will need mechanical support. You can use parallel cables with fine strands or water cooled cables supported by a balanced or power assisted arm to assist in manipulating those cables. So that's not really a big deal.

And 2MW isn't that ambitious considering much larger switched power systems exist like the 70MW 25 cycle static inverters for Amtrak's system in Sunnyside yards. See also large scale PV solar installs.

A quick thought experiment...

If you wanted to transfer 2MW, you could do it at 200 amps and 10,000 volts.

Two 200 amp conductors, 3 meters long, and 10 mm^2 cross sectional area will come out at half a kilogram. 400 watts of heating will happen in the wire, which could be cooled by a 1mm^2 water/steam cooling pipe running at 1 ml/sec. That weighs another 6 grams.

Insulating a 10,000 volt supply sounds a lot, but if the wire was insulated with PTFE, with a 10x safety margin, you would only need a thickness of 1mm on each conductor. Total weight 140 grams.

So - the total weight of a 2 Megawatt human-safe cable could, with the right engineering, be under a kilogram for 3 meters of cable, plenty to hook up your car or truck.

10kw? You will either need top tier, liquid cooled IGBTs or magnetics — both are not an option on a car. Maximum what FETs your money can buy can handle is 1500V.

It's not them being that heavy, it's them being very stiff.

IGCT's can handle a few kV and 1000's of amps. Plus you can setries them and increase the blocking voltage. Same goes for IGBT's, SCR's.

Medium voltage charging isn't a big challenge considering some mining equipment is already powered by medium voltage. Those mammoth draglines and bucket excavators are powered by an actual high voltage extension cord that is moved around with the machine. They even have plugs and connectors, saw one rated for 25kV and 600A, three phase. That's almost 26MW. Totally doable.

DC electrical systems go far bigger than 2MW. The science and engineering is well known.

Thats why this is more of a standardisation effort than a research effort. And considering what a massive fuckup CCS made of electric car chargers (there are 5+ incompatible standards!), lets hope they've learned their lessons for trucks.

You bring up a good point. Perhaps the solution is just to eliminate or reduce the human factor. I imagine for anything equipment so large it requires such a setup for charging would probably be worth the investment in an automated, or at least machine-aided, charging cable inserter.

The headline made me think bitcoin miners were using free charging stations to power their mobile mining PCs.

haha, this is actually quite witty ^ ^

Why not just run multiple chargers in parallel?

That's kinda what they are underneath, but things are never that simple.

For example, getting all that power across a single "cable" (or bundle of cables, or connector of some kind) introduces interesting engineering issues. Heat is a big problem, and watercooled cables are more and more common even in regular EVs. The article also talks about how conductive dust can be a massive issue and how they need to work around that.

But why bother bundling the parallel cables? It's probably faster / easier to hook up six separate flexible cables than a single bundle that's incredibly stiff and heavy.

I'm assuming since even 250kw EV chargers require liquid cooling and are already difficult to work with (limited length, extremely stiff and a lot of hardware to safely connect), that it becomes a bit cumbersome to work with 8 of those cables.

And even if you are reusing the same connectors and cables, I'm assuming it would need some kind of orchestration to have all the chargers work in unison. And at that point designing a single connector sounds like a logical next step. Especially if they are going to design it to work in the harsh environments they expect.

But I'm also just a layperson, so I absolutely don't know for sure.

Higher voltages and liquid cooled cables permit higher power levels without making the cables and connectors unreasonably large and heavy. You can see this in Tesla's "V3" supercharger, where they increased the power to 250 kW, but actually made the cables thinner by adding liquid cooling.

Of course, high voltages do brings other issues, like risk of arcing, that need to be mitigated.

Is it realistic to remove ventilation with all that conductive dust floating around?

Presumably the ventilation and filtration requirements will be significantly reduced rather than completely eliminated.

Electricity is not a source of energy, you need to burn something else to generate it. Solar, wind and hydro only takes us so far. Batteries can not compete with the energy density of dead trees, it's actually two orders of magnitude off.

Try burning dead trees or their derivatives indoors or underground and suddenly you care about zero emission vehicles. Zero emission here means that they don't emit at the place where they are used e.g. in an underground mine or a city center. Electricity generation in a power plant with proper filters is much cleaner than having many local burners emitting their exhaust right into your breathing air.

Well that doesn't help much when you're down in a hole in the ground risking your life for money that is created out of thin air.

Just to add a law of nature:

The carbon based system can drive metal based systems, but no the other way around.

So you will never be able to make food/nuclear/mining with electricity, only dead trees can make both metal and organic stuff.

This means nuclear is completely retarded.

Why quick charge instead of just doing a battery swap?

Electric car batteries are large. It is hard to remove them without also taking apart a big part of the car at the same time

You'd do the swap using machinery, not by hand.

You're right, but can you imagine how many problems could be introduced by changing batteries in an underground mine? A brand new equipment takes a single shift to gain a nice coat of mud from head to toe. I don't think it's impossible but there are a lot of challenges with regards to battery swapping that would need to be addressed before this becomes feasible for this industry.

Why would you change it underground? You'd schedule the changes in a controlled environment. Or is this naive?

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