3 ms·

The problem is you need the extra capacity on the track because you use it more there. In normal driving you accelerate to highway speeds and then coast, or yo

by zrm 5y ago

The problem is you need the extra capacity on the track because you use it more there. In normal driving you accelerate to highway speeds and then coast, or you're in city traffic and benefit from regenerative braking. On a track, you brake late on purpose because it's faster, but to stop that fast you have to rely more on traditional braking and can't recover the energy. Then you immediately want to accelerate back to high speeds again. If you put a small battery in an electric track car, it would be flat in ten minutes.

nabilhat 5y ago
If 28 kWh is enough for an entire Formula E race, I think 33.2 kWh in a Lotus would work out okay.
- ggreer 5y ago
  28kWh isn’t enough for a Formula E race. They swapped cars in the middle of the race back when they used those smaller batteries. They now use 54 kWh batteries[1], though power output is limited to less than a Tesla Model 3. Next year they’re supposed to increase power output to 350kW, which is comparable to a Model 3 Performance. Of course Formula E cars are much lighter, so acceleration and handling are far better than the Tesla sedan. 1. https://en.wikipedia.org/wiki/Spark_SRT05e https://en.wikipedia.org/wiki/Spark_SRT05e
ghostpepper 5y ago
Why can't you brake aggressively with regenerative braking?
- snypher 5y ago
  I think at peak braking, a lot of energy is lost as heat as opposed to going back into the battery.
- zrm 5y ago
  Cars can typically stop quite a bit faster than they can accelerate. This is especially true for two wheel drive cars because two wheel drive cars still have four wheel brakes. To brake as fast as the traction limit on the tires, which is what you get from disc brakes, you would need four wheel drive and then bigger than normal electric motors and everything else to be able to absorb that much power that fast. And then the battery would get really hot, especially if it was small.

by zrm 5y ago

nabilhat 5y ago

If 28 kWh is enough for an entire Formula E race, I think 33.2 kWh in a Lotus would work out okay.

ggreer 5y ago
28kWh isn’t enough for a Formula E race. They swapped cars in the middle of the race back when they used those smaller batteries. They now use 54 kWh batteries[1], though power output is limited to less than a Tesla Model 3. Next year they’re supposed to increase power output to 350kW, which is comparable to a Model 3 Performance. Of course Formula E cars are much lighter, so acceleration and handling are far better than the Tesla sedan. 1. https://en.wikipedia.org/wiki/Spark_SRT05e https://en.wikipedia.org/wiki/Spark_SRT05e

ghostpepper 5y ago

Why can't you brake aggressively with regenerative braking?

snypher 5y ago
I think at peak braking, a lot of energy is lost as heat as opposed to going back into the battery.
zrm 5y ago
Cars can typically stop quite a bit faster than they can accelerate. This is especially true for two wheel drive cars because two wheel drive cars still have four wheel brakes. To brake as fast as the traction limit on the tires, which is what you get from disc brakes, you would need four wheel drive and then bigger than normal electric motors and everything else to be able to absorb that much power that fast. And then the battery would get really hot, especially if it was small.