This week, the Tesla Model S became the first car to ever be unanimously chosen as the Motor Trend Car of the Year. It’s sexy and smooth, but the best thing about the Model S is undoubtedly its remarkable electric powertrain. Let’s see what makes it tick.
In the top-of-the-line Signature Performance trim, the 2013 Tesla Model S packs 416 horsepower and 443 lb.-ft of torque, and can achieve 0-60 mph in just 4.4 seconds. How does a 4,650 lb. car do all this without any gasoline? The obvious answer is of course, sorcery.
But the truth may even be more amazing. The Model S uses a liquid-cooled, lithium-ion battery that includes 7,000 battery cells for 85 kilowatt-hours (kWh) powered by an AC electric motor mounted between the rear wheels. Truly incredible stuff, but what does that even mean?
Well, it all starts with the 3-phase, 4-pole electric motor. The same one, in fact, that Tesla used in their previous Roadster model. A 3-phase, 4-pole motor generates a rotating electrical field at approximately one-fourth the frequency of the AC power supply. This technology was actually discovered by the company’s namesake, innovator Nikola Tesla.
There is an important designation here, because there are plenty of DIY electric car conversions out there that use a DC motor. DC motors are cheaper, but an AC motor places greater emphasis on performance, is safer, more simple to install and more adaptable to moving at different speeds. If a DC motor blows, it’s very likely to leave your converted car in a pile of burned wires. If an AC motor fails, the engine simply fails. No flames. No wonder, then, that the 85 kWh version will run you between $84,900 and $97,900. That’s the price of technology these days, but it’s also the price of whisper-quiet, zero emissions supercar performance.
Back to those 7,000 batteries. Panasonic supplied the lithium-ion cells for the Model S, which uses them as a flat part of the platform (rather than literally piecing thousands of laptop batteries together, like the Roadster did) to increase stability and balance. The cells are also liquid-cooled, constantly monitored to cool or warm the batteries so that they’re always operating at peak performance (and not exploding).
The cells connect to cathodes (electronic conductors through which current flows out) made of nickel-cobalt-aluminum. The most powerful kind of cathods are cobalt dioxide, but these are expensive as all hell and tend to – you guessed it – blow up. A nickel-cobalt-managanese setup lowers the cost, and makes it possible to tune for greater range or performance. Tesla elected to replace the manganese with aluminum, making it even more affordable.
Those cathodes send power to the wheels, which move an extremely lightweight all-aluminum body and high-strength steel frame through the air at just a 0.24 drag coefficient – the lowest of any production car. Full electric power with that kind of weight savings and drag comes out to about 89 MPGe and a 265-mile range. Does that make the 2013 Tesla Model S the car of the year? We’ll leave that up to you, but no matter what you think, you have to admit its technology is truly something to admire.
Thanks for reading Pop The Hood, a weekly autoMedia.com feature that examines the industry’s latest innovations and what makes them tick. If you enjoyed this column, check out these past entries in our Pop The Hood archive.
AutoMedia - Tesla Model S
- Model S - 40 kWh ($49,900)
- Model S - 60 kWh ($59,900)
- Model S - 85 kWh ($69,900)
- Model S Performance - 85 kWh ($84,900)
- Model S Signature - 85 kWh ($87,900)
- Model S Signature Performance - 85 kWh ($97,900)