5 ms·

I don't want 1000 hp in a car. I'd be happy with say 200 hp and go for extreme range instead. I have no problem with a car that takes 12 seconds to accelerate t

by 2sk21 10y ago

I don't want 1000 hp in a car. I'd be happy with say 200 hp and go for extreme range instead. I have no problem with a car that takes 12 seconds to accelerate to 60 MPH. I would not mind paying say $75000 for such car but but it doesn't exist. Is this caused by the cost of the electric powertrain? Are they forced to go upmarket?

thephilsproject 10y ago
With an electric drivetrain, it's easy to go for high power. As the battery capacity increases, so does the maximum available current. This means that maximum power scales with maximum range from the battery perspective. Then (and I am simplifying this), higher current motor controller, a bigger motor (they are not a big component anyway) and slightly chunkier drivetrain to handle the torque. You don't have the same limitations of a high powered ICE with regards to cooling and packaging. I can't imagine that the difference between a 200kW and an 800kW drivetrain is more than ~5% of the cost of the car.
- Matthias247 10y ago
  I guess the same. On top of that I think that the top power output doesn't correlate a lot to the actual range, since that amount of power will not be used for an extended timeframe. I guess even if you have 1000HP you will on average drive around with less than 50HP due to speed limits and traffic jams. The smaller sized motor(s) might have a higher efficiency with that load than the bigger sized one(s) and of course the parts might be lighter, which will really yield more range. But marketing 10 times the power is probably easier than 30% more range.
- dogma1138 10y ago
  No it doesn't it's the complete opposite the battery capacity decreases with the max current draw from each cell... If you have a battery with high capacity it would have a very small sustained draw and vise versa. The chemistry that allows for dense storage doesn't allow for high capacity and vise versa. Some of the new chems that are specially designed for EV's try to marry the best of both worlds but in both cases you can have a considerably higher capacity or considerably more power if you use chem that was optimised for either.
  - thephilsproject 10y ago
    Yes, changing chemistries does change the energy/power density ratio. However I was referring to within a single chemistry. Hence why the higher capacity Teslas have higher performance too. An ICE doesn't get faster if you put a bigger fuel tank in.
    - dogma1138 10y ago
      Not really if you just increase the capacity of each cell you decrease the maximum power draw so the performance goes down. If you just add cells you increase the weight of the car which can also have a negative or neutral effect on performance.
      - thephilsproject 10y ago
        This doesn't make sense. By that logic, a lithium battery the size of a house wouldn't be able to power an LED. If you have two lithium batteries which are identical with the exception that one is double the capacity, the larger battery will be able to provide double the current at the same voltage and thus double the power. Lithium batteries are rated for current draw as a multiple of their capacity.
        dogma1138 10y ago
        It's nothing to do with the size of the battery it's with the chemistry and yes a batter the size of a house might very well not be able to power a single LED because of its internal resistence. Lithium batteries are rated for current draw based on their chemistry please do some basic reasearch. And no if you have 2 identical 18650 they'll have the same density and sustained and peak current draw if not they are not identical. Cell size, chemistry, internal resistance, breakage and short currents etc are all variables based on the exact make of the battery.
lucaspiller 10y ago
Horsepower isn't a good measure of how fast it takes to accelerate, that's the power to weight ratio. The Nissan Leaf does 0-60 in 11.5 seconds and has a 107hp drivetrain. Unfortunately the range is around 1/4 of what you want. The battery pack retails for $5k, so let's say it costs another $15k for 400 mile total range (assuming nothing else changes, e.g. extra weight). Would you pay $50k for one with a 400 mile range?
- 2sk21 10y ago
  I think would. A car similar to Leaf with a 400 mile range would be very attractive for me.
4ad 10y ago
There is little to none correlation between range and maximum power (in fact there might be a very slight negative correlation in favor of higher power cars). There's no tradeoff to be made here.
- 2sk21 10y ago
  Interesting. I was sure that a more powerful motor and powertrain would be heavier and more expensive to manufacture. Looks like I need to study more on this.
ams6110 10y ago
That's my take as well. 12 seconds might be a bit leisurely but 8 would be more than enough. I'll never need 2.5 0-60 in a car. I'd much rather have more range. Range and lack of ubiquitous quick "refueling" are the two issues that keeps me away from electric cars.

by 2sk21 10y ago

thephilsproject 10y ago

With an electric drivetrain, it's easy to go for high power. As the battery capacity increases, so does the maximum available current. This means that maximum power scales with maximum range from the battery perspective. Then (and I am simplifying this), higher current motor controller, a bigger motor (they are not a big component anyway) and slightly chunkier drivetrain to handle the torque. You don't have the same limitations of a high powered ICE with regards to cooling and packaging. I can't imagine that the difference between a 200kW and an 800kW drivetrain is more than ~5% of the cost of the car.

Matthias247 10y ago
I guess the same. On top of that I think that the top power output doesn't correlate a lot to the actual range, since that amount of power will not be used for an extended timeframe. I guess even if you have 1000HP you will on average drive around with less than 50HP due to speed limits and traffic jams. The smaller sized motor(s) might have a higher efficiency with that load than the bigger sized one(s) and of course the parts might be lighter, which will really yield more range. But marketing 10 times the power is probably easier than 30% more range.
dogma1138 10y ago
No it doesn't it's the complete opposite the battery capacity decreases with the max current draw from each cell... If you have a battery with high capacity it would have a very small sustained draw and vise versa. The chemistry that allows for dense storage doesn't allow for high capacity and vise versa. Some of the new chems that are specially designed for EV's try to marry the best of both worlds but in both cases you can have a considerably higher capacity or considerably more power if you use chem that was optimised for either.
- thephilsproject 10y ago
  Yes, changing chemistries does change the energy/power density ratio. However I was referring to within a single chemistry. Hence why the higher capacity Teslas have higher performance too. An ICE doesn't get faster if you put a bigger fuel tank in.
  - dogma1138 10y ago
    Not really if you just increase the capacity of each cell you decrease the maximum power draw so the performance goes down. If you just add cells you increase the weight of the car which can also have a negative or neutral effect on performance.
    - thephilsproject 10y ago
      This doesn't make sense. By that logic, a lithium battery the size of a house wouldn't be able to power an LED. If you have two lithium batteries which are identical with the exception that one is double the capacity, the larger battery will be able to provide double the current at the same voltage and thus double the power. Lithium batteries are rated for current draw as a multiple of their capacity.
      - dogma1138 10y ago
        It's nothing to do with the size of the battery it's with the chemistry and yes a batter the size of a house might very well not be able to power a single LED because of its internal resistence. Lithium batteries are rated for current draw based on their chemistry please do some basic reasearch. And no if you have 2 identical 18650 they'll have the same density and sustained and peak current draw if not they are not identical. Cell size, chemistry, internal resistance, breakage and short currents etc are all variables based on the exact make of the battery.

lucaspiller 10y ago

Horsepower isn't a good measure of how fast it takes to accelerate, that's the power to weight ratio. The Nissan Leaf does 0-60 in 11.5 seconds and has a 107hp drivetrain. Unfortunately the range is around 1/4 of what you want. The battery pack retails for $5k, so let's say it costs another $15k for 400 mile total range (assuming nothing else changes, e.g. extra weight). Would you pay $50k for one with a 400 mile range?

2sk21 10y ago
I think would. A car similar to Leaf with a 400 mile range would be very attractive for me.

4ad 10y ago

There is little to none correlation between range and maximum power (in fact there might be a very slight negative correlation in favor of higher power cars). There's no tradeoff to be made here.

2sk21 10y ago
Interesting. I was sure that a more powerful motor and powertrain would be heavier and more expensive to manufacture. Looks like I need to study more on this.

ams6110 10y ago

That's my take as well. 12 seconds might be a bit leisurely but 8 would be more than enough. I'll never need 2.5 0-60 in a car. I'd much rather have more range. Range and lack of ubiquitous quick "refueling" are the two issues that keeps me away from electric cars.