4 ms·

> Refueling with an ICE takes no time at all and can be done anywhere. So right. It is truly amazing that more people don't realize the disconnect here betwee

by rplst8 11y ago

> Refueling with an ICE takes no time at all and can be done anywhere. So right. It is truly amazing that more people don't realize the disconnect here between current motor fuels and electricity. The average gallon of gasoline contains 33 kWh of energy. You can pump about 15-20 gallons in 5 minutes or so. That's equivalent to around 6 MWh or 21,000 MJ of energy, every hour. Less if you allow for the time between cars. The average household electrical supply in the US is 200A at 240V which can supply a paltry 48 kWh or 172 MJ each hour. And that's if one were able to use the supply at full capacity. Electric cars require 1/4 to 1/3 of the energy as typical ICE counterparts, but the fuel delivery systems are separated by factor of over 100. We're still well over an order of magnitude apart on the fueling convenience factor. Installing three phase 480V 400A (1.2 MJ per hour) service to homes would help solve this, but would be much more dangerous to work with - even if the charging systems on the EVs could use it.

_ph_ 11y ago
An average car in Germany would require about 10kWh per day recharge, this can be done on a plain wall socket. Even if you drive twice that range every day, you would not need anywhere close to the powers you are talking about. The comparison about the energy transfer speed between gasoline and electricity is misleading. First of all, an electric vehicle is about 3x as effective, so you would need only a third of the energy transfer speed. Then, with a gasoline vehicle, you have always to drive to a fuel station and wait for it to be filled up - there speed matters. With an electric vehicle, the common case should be overnight recharge, so charge speed does not matter much there. This also means, that you are likely to start with a completely filled battery every morning. So unless you are doing long distance travel, you never have to recharge except over night (or, if your work parking facilities offer electrical outlets, during work time). And for long distance travel, there are Superchargers. Yes, those do take longer than refueling gasoline, but unless you travel long distance every day, this might be a good tradeoff.
- rplst8 11y ago
  > The comparison about the energy transfer speed between gasoline and electricity is misleading. First of all, an electric vehicle is about 3x as effective, so you would need only a third of the energy transfer speed. I stated that in my original reply. > With an electric vehicle, the common case should be overnight recharge, so charge speed does not matter much there. I know here in the DC metro people have 100 mile per day commutes - and more. That is 1/3 to 1/2 (all in some cases) of the battery capacity of most EVs. A regular 20A wall charger has no chance of replenishing that overnight, and at 85% charging efficiency, a level 2 charger or whatever would struggle to supply 40+ kWh over night as well. Slow charging EVs may work for some, maybe even most - but definitely not everyone. Especially in the rural United States.
  - Kastaka 11y ago
    This looks like a Europe vs US comparison problem? In Europe you're unlikely to be travelling vast distances on a regular basis, whereas it's much more common in the US, so the range problems become much more important in the US than they are in Europe.
    - Reason077 11y ago
      In Europe we also have 230V power as standard, so the standard 32A EV wall chargers provide 7kW - more than enough to charge any EV overnight. Even a standard UK wall socket can provide about 3kW. In Germany they have 3-phase wiring right into homes, so even faster home charging is possible there.
Reason077 11y ago
Audi have been talking about 800V, 300kW charging - or 250km of range in 10 minutes. That's less than the time it takes for a bathroom break and a coffee. The difference between filling an ICE vehicle and fast-charging an EV becomes pretty negligible at that point. (The CCS plug standard has been future-proofed to support these kinds of speeds) All of this is only a concern, of course, for long-distance road trips. Which for most drivers are relatively rare events.

by rplst8 11y ago

_ph_ 11y ago

An average car in Germany would require about 10kWh per day recharge, this can be done on a plain wall socket. Even if you drive twice that range every day, you would not need anywhere close to the powers you are talking about. The comparison about the energy transfer speed between gasoline and electricity is misleading. First of all, an electric vehicle is about 3x as effective, so you would need only a third of the energy transfer speed. Then, with a gasoline vehicle, you have always to drive to a fuel station and wait for it to be filled up - there speed matters. With an electric vehicle, the common case should be overnight recharge, so charge speed does not matter much there. This also means, that you are likely to start with a completely filled battery every morning. So unless you are doing long distance travel, you never have to recharge except over night (or, if your work parking facilities offer electrical outlets, during work time). And for long distance travel, there are Superchargers. Yes, those do take longer than refueling gasoline, but unless you travel long distance every day, this might be a good tradeoff.

rplst8 11y ago
> The comparison about the energy transfer speed between gasoline and electricity is misleading. First of all, an electric vehicle is about 3x as effective, so you would need only a third of the energy transfer speed. I stated that in my original reply. > With an electric vehicle, the common case should be overnight recharge, so charge speed does not matter much there. I know here in the DC metro people have 100 mile per day commutes - and more. That is 1/3 to 1/2 (all in some cases) of the battery capacity of most EVs. A regular 20A wall charger has no chance of replenishing that overnight, and at 85% charging efficiency, a level 2 charger or whatever would struggle to supply 40+ kWh over night as well. Slow charging EVs may work for some, maybe even most - but definitely not everyone. Especially in the rural United States.
- Kastaka 11y ago
  This looks like a Europe vs US comparison problem? In Europe you're unlikely to be travelling vast distances on a regular basis, whereas it's much more common in the US, so the range problems become much more important in the US than they are in Europe.
  - Reason077 11y ago
    In Europe we also have 230V power as standard, so the standard 32A EV wall chargers provide 7kW - more than enough to charge any EV overnight. Even a standard UK wall socket can provide about 3kW. In Germany they have 3-phase wiring right into homes, so even faster home charging is possible there.

Reason077 11y ago

Audi have been talking about 800V, 300kW charging - or 250km of range in 10 minutes. That's less than the time it takes for a bathroom break and a coffee. The difference between filling an ICE vehicle and fast-charging an EV becomes pretty negligible at that point. (The CCS plug standard has been future-proofed to support these kinds of speeds) All of this is only a concern, of course, for long-distance road trips. Which for most drivers are relatively rare events.