3 ms·

My house can load 105A. I sometimes use 120 kWh on a really cold day, so it's not peaking anywhere near that current, at least not for long. I'm not driving 40

by kpil 8y ago

My house can load 105A. I sometimes use 120 kWh on a really cold day, so it's not peaking anywhere near that current, at least not for long. I'm not driving 400km every day so the grid will definitely handle it. But there is a lot of potential to reduce network costs if the charger negotiated with the grid.

juliangoldsmith 8y ago
Your house can load 105A, but that's most likely at 120V/220V, and as you said, it doesn't maintain that for long. Based on 120 kWh over 24 hours, your house, on a cold day, draws around 500 W. To fully charge a single 100 kWh battery, like you'd find in a new Model S, in an hour, you would need to draw 100 kW. That would be 200 times the average load on your house, drawn continuously, and that's only to charge one vehicle. Something like a flywheel battery does have a lot of potential to save money, or even earn money, if it communicated with the grid. A large rotating mass could potentially store a lot of energy, and would be increasingly useful with the rise of renewable energy.
- kalenx 8y ago
  120 kWh / 24h = 5000 W, not 500 Many houses in cold climates using electrical heaters will actually use at least 2-3x this energy. So yeah, 100 kW is quite streched, but we're not _that_ far from the power available in a home.
  - juliangoldsmith 8y ago
    You're correct, my mistake. Still, that would be 20 times the average load on those homes, to charge a single vehicle. To move that power 100 feet, like from a busbar (I think, I'm not an electrician) to the charger would require a 3/0 AWG copper cable (which has a diameter of around 2 1/2", or 5.8mm). That cable costs around $2.59 a foot, or $259 to get power to that charger. That would be undersized, since I calculated it out at exactly capacity, and that price wouldn't include conduit (since the cable isn't direct burial) or installation. Multiply that by three chargers, which I'd consider to be on the very low end of what a commercial installment would need, and you have quite a high demand for power. Five hundred amps at 480V is no joke. On the plus side, all this could spur adoption of renewable energy; with enough demand for power, investors will shovel money into renewable energy faster than it can even be used.

by kpil 8y ago

juliangoldsmith 8y ago

Your house can load 105A, but that's most likely at 120V/220V, and as you said, it doesn't maintain that for long. Based on 120 kWh over 24 hours, your house, on a cold day, draws around 500 W. To fully charge a single 100 kWh battery, like you'd find in a new Model S, in an hour, you would need to draw 100 kW. That would be 200 times the average load on your house, drawn continuously, and that's only to charge one vehicle. Something like a flywheel battery does have a lot of potential to save money, or even earn money, if it communicated with the grid. A large rotating mass could potentially store a lot of energy, and would be increasingly useful with the rise of renewable energy.

kalenx 8y ago
120 kWh / 24h = 5000 W, not 500 Many houses in cold climates using electrical heaters will actually use at least 2-3x this energy. So yeah, 100 kW is quite streched, but we're not _that_ far from the power available in a home.
- juliangoldsmith 8y ago
  You're correct, my mistake. Still, that would be 20 times the average load on those homes, to charge a single vehicle. To move that power 100 feet, like from a busbar (I think, I'm not an electrician) to the charger would require a 3/0 AWG copper cable (which has a diameter of around 2 1/2", or 5.8mm). That cable costs around $2.59 a foot, or $259 to get power to that charger. That would be undersized, since I calculated it out at exactly capacity, and that price wouldn't include conduit (since the cable isn't direct burial) or installation. Multiply that by three chargers, which I'd consider to be on the very low end of what a commercial installment would need, and you have quite a high demand for power. Five hundred amps at 480V is no joke. On the plus side, all this could spur adoption of renewable energy; with enough demand for power, investors will shovel money into renewable energy faster than it can even be used.