3 ms·

> have a minute to plug in? Still sufficient to get from 10 to 35 percent state of charge. Scaling that to something the size of an EV pack will require one m

> have a minute to plug in? Still sufficient to get from 10 to 35 percent state of charge. Scaling that to something the size of an EV pack will require one massive cable/connector. Call it 5kw/h in 1/60 hours, thats 3000kw, at 700v thats still roughly 4000 amps. (Please correct my head math.) Charging one car could suck up more power than an entire neighbourhood. Say four or five chargers operating at once ... every roadside charging station will need its own electrical substation.

jcsager 6mo ago
Fjord ferries in Norway are up around that sort of charge rate, but for 30 mins instead of 5. That kind of battery charging performance is pure marketing until our local LV supply network is uplifted!
- beej71 6mo ago
  I was so impressed by this when I saw it. Big-ass cable. :) Great ferry trip.
g4cg54g54 6mo ago
chargers of that size generally have there own internal (sometimes even shared by multiple receptacles) batteries
SECProto 6mo ago
> Call it 5kw/h in 1/60 hours, thats 3000kw, at 700v thats still roughly 4000 amps. (Please correct my head math.) 5 kWh * 60 = 300 kW at 800V (typical charging voltage) that is 375A (still huge, but an order of magnitude less)
baq 6mo ago
substation...? more like an SMR
dgacmu 6mo ago
What's nice there, though, is that the total amount of _energy_ needed at a charging station is roughly fixed(), regardless of how fast you charge the cars. So if you're provisioned for the needed total energy inflow, you can to a reasonable degree compensate for having a more bursty high-rate charging load by having some amount of local energy storage as a buffer. () - Assuming you provision for the highest-traffic-volume day. Ignoring potential induced demand of making it a little easier to drive, which I suspect is pretty bounded - people need pee and stretch breaks anyway.
- sandworm101 6mo ago
  For numbers, just follow traffic at a busy gas station. Roughly 100 vehicles per hour is typical. So imagine having to charge 100 Teslas per hour, or just over one telsa per minute. That is still an insane amount of power.
  - SideburnsOfDoom 6mo ago
    That's not the math though. Approximately 0% of those vehicles at the busy gas station ever fuel up at home. Most of those EV fuel up most of the time at home or at a "Destination Charger" at places other than a roadside DC Super-Fast charger. I see figures given that around 80% of EV charging is done at home (1). That doesn't mean that the other 20% has to be super-fast though, it will be less than that. https://www.energy.gov/topics/national-ev-charging-network# https://www.energy.gov/topics/national-ev-charging-network#
    - sandworm101 6mo ago
      Only people with houses get to charge at home. All the non-rich who don't own houses are stuck with commercial chargers. It will be the reality for so so many people.
      - SideburnsOfDoom 6mo ago
        1) Do you dispute the 80% at home figure, and if so, on what basis? 2) Are you claiming that all "not at home" commercial charging is "busy gas station" style fast charging while waiting, and if so, on what basis? Applying gas station capacity math to EVS as if they are like for like will give wrong answers. Your point about access to charge at home is valid but unrelated to that.
adrian_b 6mo ago
Like others have pointed, you have made a mistake in your computation. The currents that are required are only of hundreds of amps and the latest chargers can provide up to 1000 A. Also like others have said, it does not matter how fast you charge a car, the total energy consumption is the same, so fast chargers do not require changes in the power supply of a charging station. The fast chargers that enable this full charging in a few minutes have their own internal batteries, to enable them to pull only the average power from the electrical grid, not the peak power. The new fast chargers that can achieve the times reported in TFA use a somewhat higher voltage than the older chargers, of 1000 V, to reduce the current.
- sandworm101 6mo ago
  Ya, i missed a 0, but chargers with batteries are irrelevant for charging stations by a highway like a modern gas station. They have a constant flow of vehicles. There will be no time for a buffer battery when the next customer is maybe 45 seconds behind the last. A buffer battery may have a place for a home charger, but a constant-use commerical charger is a very different thing. Or think of a rental car stand at an airport, or a truck/buss depot. They will have a vehicle arriving every minute and every hour wasted charging is an hour less rental time.
  - adrian_b 6mo ago
    A charging station must be supplied with a power determined by the number of cars it must charge during a given time interval, e.g. a day or an hour. It does not matter if it charges 30 cars per hour by having 3 chargers that charge in 6 minutes (including connection/disconnection times) or by having 15 chargers that charge in 30 minutes. So it is not the charging speed that matters, but the amount of electric vehicles that want to use a charging station. The charging speed matters only for the car owners, as it determines the time they must spend at the charging station. Normally, a charger that is 10 times faster is not 10 times more expensive, so faster chargers should also benefit the charging station owners, because they would need to invest less for servicing a given amount of traffic, by buying less chargers.

jcsager 6mo ago

Fjord ferries in Norway are up around that sort of charge rate, but for 30 mins instead of 5. That kind of battery charging performance is pure marketing until our local LV supply network is uplifted!

beej71 6mo ago
I was so impressed by this when I saw it. Big-ass cable. :) Great ferry trip.

g4cg54g54 6mo ago

chargers of that size generally have there own internal (sometimes even shared by multiple receptacles) batteries

SECProto 6mo ago

> Call it 5kw/h in 1/60 hours, thats 3000kw, at 700v thats still roughly 4000 amps. (Please correct my head math.) 5 kWh * 60 = 300 kW at 800V (typical charging voltage) that is 375A (still huge, but an order of magnitude less)

baq 6mo ago

substation...? more like an SMR

dgacmu 6mo ago

What's nice there, though, is that the total amount of _energy_ needed at a charging station is roughly fixed(), regardless of how fast you charge the cars. So if you're provisioned for the needed total energy inflow, you can to a reasonable degree compensate for having a more bursty high-rate charging load by having some amount of local energy storage as a buffer. () - Assuming you provision for the highest-traffic-volume day. Ignoring potential induced demand of making it a little easier to drive, which I suspect is pretty bounded - people need pee and stretch breaks anyway.

sandworm101 6mo ago
For numbers, just follow traffic at a busy gas station. Roughly 100 vehicles per hour is typical. So imagine having to charge 100 Teslas per hour, or just over one telsa per minute. That is still an insane amount of power.
- SideburnsOfDoom 6mo ago
  That's not the math though. Approximately 0% of those vehicles at the busy gas station ever fuel up at home. Most of those EV fuel up most of the time at home or at a "Destination Charger" at places other than a roadside DC Super-Fast charger. I see figures given that around 80% of EV charging is done at home (1). That doesn't mean that the other 20% has to be super-fast though, it will be less than that. https://www.energy.gov/topics/national-ev-charging-network# https://www.energy.gov/topics/national-ev-charging-network#
  - sandworm101 6mo ago
    Only people with houses get to charge at home. All the non-rich who don't own houses are stuck with commercial chargers. It will be the reality for so so many people.
    - SideburnsOfDoom 6mo ago
      1) Do you dispute the 80% at home figure, and if so, on what basis? 2) Are you claiming that all "not at home" commercial charging is "busy gas station" style fast charging while waiting, and if so, on what basis? Applying gas station capacity math to EVS as if they are like for like will give wrong answers. Your point about access to charge at home is valid but unrelated to that.

adrian_b 6mo ago

Like others have pointed, you have made a mistake in your computation. The currents that are required are only of hundreds of amps and the latest chargers can provide up to 1000 A. Also like others have said, it does not matter how fast you charge a car, the total energy consumption is the same, so fast chargers do not require changes in the power supply of a charging station. The fast chargers that enable this full charging in a few minutes have their own internal batteries, to enable them to pull only the average power from the electrical grid, not the peak power. The new fast chargers that can achieve the times reported in TFA use a somewhat higher voltage than the older chargers, of 1000 V, to reduce the current.

sandworm101 6mo ago
Ya, i missed a 0, but chargers with batteries are irrelevant for charging stations by a highway like a modern gas station. They have a constant flow of vehicles. There will be no time for a buffer battery when the next customer is maybe 45 seconds behind the last. A buffer battery may have a place for a home charger, but a constant-use commerical charger is a very different thing. Or think of a rental car stand at an airport, or a truck/buss depot. They will have a vehicle arriving every minute and every hour wasted charging is an hour less rental time.
- adrian_b 6mo ago
  A charging station must be supplied with a power determined by the number of cars it must charge during a given time interval, e.g. a day or an hour. It does not matter if it charges 30 cars per hour by having 3 chargers that charge in 6 minutes (including connection/disconnection times) or by having 15 chargers that charge in 30 minutes. So it is not the charging speed that matters, but the amount of electric vehicles that want to use a charging station. The charging speed matters only for the car owners, as it determines the time they must spend at the charging station. Normally, a charger that is 10 times faster is not 10 times more expensive, so faster chargers should also benefit the charging station owners, because they would need to invest less for servicing a given amount of traffic, by buying less chargers.