- cross-posted to:
- tech@kbin.social
- cross-posted to:
- tech@kbin.social
Fully Charged in Just 6 Minutes – Groundbreaking Technique Could Revolutionize EV Charging::Typically, it takes around 10 hours to charge an electric vehicle. Even with fast-charging techniques, you’re still looking at a minimum of 30 minutes – and that’s if there’s an open spot at a charging station. If electric vehicles could charge as swiftly as we refill traditional gas vehicles, it wo
Alright, so let’s assume a 100kWh battery like some tesla models. Now, someone made such a battery that can be charged in 6 minutes… how much power does it need?
100 kW•h / 6minutes = 100kW•h / 0.1h = 1000kW = 1MW
So, we need 1 MEGAWATT car chargers … that’s some power required there.
Possibly even more significant, those are some large cables and even larger contacts required. There’s no way a 1MW disconnect is just a little plug you stick into your car.
In fact as an electrician I can’t think of anything even near megawatt class that would be connected with a portable cord, or at a voltage that would be safe for consumers to handle.
Maybe someone in the mining industry or similar can chime in, but I currently run a pumping station that includes 3000HP motors (2.2MW). These are 4kV 3 phase units where each phase cable is as thick as your arm. All connections are bolted and taped to avoid corona discharge. Just dragging the cable to the car would be more than the average driver could handle.
I don’t see a way to get these power levels into a car short of a standardized and semi-automated docking system. Or maybe go back to the idea of standard swappable batteries where the battery then is charged rapidly for the next customer.
The power lines in the cable are disconnected inside the charger by a contactor until communication with the car is confirmed established with a handshake, and then it connects power to the cable. If the communication with the car drops at any point, the contactor disconnects the power to the cable. It requires both effort and knowledge to bypass this design, it basically can’t happen accidentally.
Also, the cables you mention are that large, because they’re passively cooled, DC car chargers have watercooled cables so they can be much thinner without overheating. And at 4kV you’re looking at significantly different insulation thickness as well, compared to the 400-800V that electric cars use.
Electric busses already have automated docking systems, the only problem I see is cost
https://assets.foleon.com/eu-central-1/de-uploads-7e3kk3/39195/17_syb21_content1.79205c469709.jpg
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That’s 4,350 amps @230vac. The service fuse for my entire home is 80 or 100amp (single phase domestic dwelling Australia). The main breaker is 63amp.
DC fast charging typically runs at 400 volts, with some cars doing 800. They also do it with highly specialized equipment and service lines you’d never see in a residential setting.
When charging at home, you have all night. A 50A circuit will go 0-100 on most cars in that time, and if you look at what most people actually drive you can generally get by on much less.
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A fair question. Depends on the house. 100-200 is common, depending on the age of the house. 100 or less if your house predates central air conditioning, and 150-200 is far more common in the last few decades. Most people charge overnight, and they’re not using much else. If you truly have a smaller connection, even 20A @240V is surprisingly useful. Or hell, a normal outlet.
That may be your battery’s capacity, but that’s not necessarily your draw. How big is your gas tank? Do you give it ~15 gallons each day? My car gets about 3.5 miles per kWh. If I drive it 70 miles, that’s 20 kWH and then the car stops charging. And I pay about $2.50 for it. What would gas cost?
Solar direct to car is actually a terrible idea. Just hook something up to the grid if you want solar, but it’s pretty cheap without. You’re overthinking it, probably because your 80 kWH per day number is so out of whack.
Again, no. Well, it’s cool if you can get it but it’s really not needed because home electricity is generally way cheaper than gasoline.
Fast charging uses up to 1000 V DC, and the current limits of conductors are typically set by the temperature it reaches when conduction losses heat them up. This can be (and is) offset by liquid cooling, allowing current installations to deliver up to 650 A (Tesla supercharger v3).
With improvements, it’s not far off 1 MW.
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thats assuming 100% efficiency. which is impossible
I’m happy with 69 efficiency. 🙃
True, so I guess 1MW won’t even be enough
Typically you’re getting about 97-99% efficiency at a supercharger in ideal conditions (not running heat, around 70F outside, etc).
most EV cars are more like 60kwh though.
The person above you said Tesla. Most newer Tesla models are 75 kWh-120kWh.
incorrect. most are 56kwh
Oh damn, I didn’t realize Tesla started making the standard range again. When I got my LR RWD in 2018, they were not selling the SR anymore. However, their Model Y starts at 75kWh, and their Model S and X are only 100kWh now.
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I think 100kWh is ideal for a Model 3. I drove my LR RWD across the US (MS to CA to WA) and didn’t really have an issue. It was only bad when it got really cold outside, so having an extra 30% would cover that. It would have about 400 miles of range on a full charge, and 20 mins at a super charger would get you from 10% to 80%, so 300 miles, or another 4 hours of driving.
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At home, most people are only charging about 10-20% every night. For 100kWh, let’s say 20kWh, which is 60 miles. Most people at home will be using a 240v 50A outlet, which outputs 12kW. You’d be done charging in about 2 hours at 95% efficiency for 21kWh from the outlet (heat loss and whatnot does take a significant portion of charging). At my place with $0.13/kWh, that would just be a measly $2.75 at 95% efficiency. Wayyyy cheaper than gas. That’s around the same as a car with 85mpg at $4/gal gas. Most cars are around 30mpg on a good day.
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Tesla semi is meant to be able to charge at 1mw, which makes sense considering the size of the battery, bigger battery means more cells and more space for cooling. The truck is also meant to support 1mw with the new v4 chargers. So if you believe Tesla (which is hard because of Musk), it is coming.
Charging that rapidly is only possible for some but not all 100% of the battery as you have to slow down as you approach 100%. 350kw chargers slow down around 80% (I’ve gone as high as 85% before I’ve seen the slow down). This happens at all charging speeds to protect the battery, even 7kw chargers slow down for the last couple of percent.
However charging to 100% of the time on ultra rapid chargers is monumentally dumb as it’s considerably more expensive per kWh than slow chargers, slower for that last 20%, blocks chargers for longer, and isn’t good for the long term health of the battery. It is as quick to charge twice to 80% than it is once to 100% on the same charger for 60 to 70% more range from charging twice. This is true because you avoid slowing down at the end of the charge.
You’re speaking with current lithium battery technology in mind. Supposedly, scientists in the article figured out a new technology that can be charged in 6 minutes. No word on whether it’s still necessary to slow down at the end, or charging efficiency. Time will tell I guess
It’s highly unlikely that they solve what is essentially a heat distribution problem with new battery materials. If you stick a huge number of cells in a giant cooling system then you can charge even lithium considerably faster than we do now for all of the 100%.
We are limited by the space, how good the battery pre condition charging is,maintenance schedule of the car and charging point.
My car has a separate fluid cooling system for ultra rapid charging that has its own maintenance schedule, if this system was bigger and didn’t have to go a minimum of 12 months between changes then it could be charged for longer at higher speeds.
If my car had a bigger battery with more cells in a suitable arrangement then again I could charge faster for longer as the charge is spread out across the battery. However eventually you’ll hit the point that you are only charging a few of the cells as the rest are full and you have to slow down or the battery will get too hot.
I just don’t see them completely solving the heat problem, just improving the current percentages.