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The difference between the Roadster and the Roadster sport is that the Roadster has extra battery horsepower available that it can't use because the motor and/or PEM is limiting it. I said that you build the motor to use all your available battery horsepower because the motor is cheap compared to the battery. Tesla discovered that they got it wrong the first time and the motor was limiting the car, so they made a better motor and charged more money for it.
I am an acceleration junkie and was not willing to pay $20k for the marginal improvement of the sport even though I do regret not getting the adjustible suspension.
Has anyone already done the math on what the Roadster would do with 6,831 of the cells used in the 85 kWh pack in terms of 0-60?
The difference between the Roadster and the Roadster sport is that the Roadster has extra battery horsepower available that it can't use because the motor and/or PEM is limiting it. I said that you build the motor to use all your available battery horsepower because the motor is cheap compared to the battery. Tesla discovered that they got it wrong the first time and the motor was limiting the car, so they made a better motor and charged more money for it.
I am an acceleration junkie and was not willing to pay $20k for the marginal improvement of the sport even though I do regret not getting the adjustible suspension.
I heard something really interesting from an EV drag racer, and I will attempt to paraphrase.
The batteries in the Model S probably are used at around 4C when bursted. This means the 40kWh battery delivers 160kW ( 215 hp ) and the 85kWh battery delivers 340kW ( 456 hp )
There are batteries that can be used at much higher C rates ( like 25C or even higher ) in bursts, and that is what EV drag racers use.
So a 20kWh pack can deliver 670 horsepower. However they tend to be much less energy dense.
Maybe this is a bit naive, but why wouldn't manufacturers create a (for lack of a better term) hybrid battery which has say, 5 KWh "high power, low density ala A123" and the remaining 35Kwh of "lower power, higher density."
In fact Tesla has patents on hybrid batteries. Perhaps we will see them in a future vehicle.
The idea that the entry model would be "detuned" to offer less performance in an attempt to get people to want to spend more on the top line models makes sense from a marketing standpoint, but I do suspect there are reasons why the technology is also limiting what they can do. Perhaps the marketing folks are grateful that they are forced to offer a product with built-in up-sell features...
And there's the cpu example...In marketing parlance, nothing is ever "detuned."
They simply found ways to engineer the 85kWh unit give even more juice than the 4okWh design. And then some engineer said, "Hey, we can do better still, and build a Performance model that really flies with just a few more tweaks!"
At least being a brand marketing guy, that's how I would describe it.
...This turns a refuse product ("failed high-end cpu") to a discounted "value" product.
In that case, why didn't Tesla just use a smaller inverter for the 40kW? Would it get even more range?
In that case, why didn't Tesla just use a smaller inverter for the 40kW? Would it get even more range?
In order to get more range the inverter needs to either be more efficient or lighter.
The inverter is already 90%+ efficient so there is little room to improve and making it smaller probable would make it less efficient not more.
Then weight, it probably only weighs in the ballpark of 50 pounds so there is little room to improve there either.
Has anyone already done the math on what the Roadster would do with 6,831 of the cells used in the 85 kWh pack in terms of 0-60?
Reducing the number of cells and reducing the weight would help the 0-60 a lot.
4554 of the best Model S cells would produce about the same power and shave off 300ish pounds.
That could cut the 0-60 by 3 or 4 tenths. Done right it could also lower the CG which would be great for handling.
Utilizing more battery horsepower might require a new PEM and/or motor.
In fact Tesla has patents on hybrid batteries. Perhaps we will see them in a future vehicle.