Fisker: With An EV Transmission, All Things Are Possible

Edward Niedermeyer
by Edward Niedermeyer

In my review of the VW Golf blue-e-motion on Tuesday, I noted that “the holy grail of EV development is a multi-speed transmission,” but that nobody has been able to build one that can reliably handle the 100% torque at zero RPM characteristics of an electric drivetrain. Tesla tried two different multi-speed transmissions (from X-Trac and Magna), before giving up and going with the single-speed setup that every production EV now uses. Nobody has even talked about a multi-gear EV since… until now. With Fisker’s Karma about to go to market, CEO Henrik Fisker tells Autocar that his firm is developing a multi-speed EV gearbox, and that it would improve performance in EVs like the Karma, saying

With the torque at the wheels increased by the use of a gearbox, Veyron levels of performance should be possible.

We’re as excited as anyone else by the idea of an EV with shiftable gears, but this sounds more like Fisker trying to drum up some hype for the Karma launch. After all, the Karma launches to 60 MPH in a leisurely 7.9 seconds in “stealth” (EV) mode and 5.9 seconds in “sport” mode with gas power to up the wattage… a far cry from Veyron performance. As C&D puts it:

The Karma’s initial surge is sufficiently potent to avoid damnation as a slug. But the physics conspire against it keeping pace with other $100K sports sedans.

Lugging over 4,000 lbs is certainly easier with a multi-gear transmission, but given the reliability challenge, we’d be more likely to trust an EV transmission from a reliable supplier rather than a boutique luxury PHEV maker. And until Fisker can back up the Veyron reference with some hard evidence, we’re filing this one under “intriguing but unlikely.” Still, it’s exciting to know that this technical challenge is still out there, unconquered by major manufacturer or feisty startup… in a world where cars are becoming increasingly mundane, the multi-gear EV transmission challenge is a throwback to the golden years of automotive development.

Edward Niedermeyer
Edward Niedermeyer

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  • Dynasty Dynasty on Jul 21, 2011

    A steam engine has 100% torque at zero RPM. An electrical motor has 100% torque above zero RPM.

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    • Dynasty Dynasty on Jul 22, 2011

      @golden2husky I'm not an electrical engineer, but that is what an electrical engineer told me. I don't disagree that an electrical motor has the highest current draw at startup, but the key is the motor needs to begin spinning for there to be any twisting force. A stalled electrical motor drawing full amperage is going to catch on fire (assuming the demand placed on it is too great to spin). I suppose a steam engine would also have 100% torque just at the point of the crank beginning to spin as well.

  • Robert Gordon Robert Gordon on Aug 17, 2011

    "but the key is the motor needs to begin spinning for there to be any twisting force" Nonsense. You are confusing Torque with work. Torque is a force, work is resulting effect of applying a force, power is the rate at which work is done. However applying a force to an option does not necessarily result in work. The coffee cup on your desk has a constant force being applied yet it doesn't go anywhere. Likewise you can apply a torque without anything happening.

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