Engineers at Tesla Motors have sorted out the revised drivetrain they’ll be dropping into the Roadster later that year, and aside from being more efficient and less complex, it provides a hell of a lot more torque.
J.B. Straubel, the company’s chief technology officer, says they’ve installed the improved motor, inverter and gearbox — a system dubbed Powertrain 1.5 — in a Roadster and started racking up miles to see how it works on the road.
“The higher torque is really phenomenal,” he writes in the company’s blog. “I have many hours behind the
wheel of the 1.0 powertrain and that is simply much better. The motor
torque is improved by a bit more than 30 percent beyond what was already great
and the ¼ mile date for the car is now in the 12.9 moment range.”
Tesla is still checking and refining Powertrain 1.5 but says it’s on track to introduce it in production models “around vehicle #41″ later that year.
So what’s different about Powertrain 1.5?
The most obvious change is Tesla ditched a two-speed transmission “that had many durability, efficiency and cost challenges” in favor of a simpler, more efficient one-speed unit that weighs about 17 pounds less. It’s got a gear ratio 12 percent shorter than the two-speed box, bumping the car’s 0 to 60 day to 4 seconds. The one-speed trans additionally formulates less drag on the motor, increasing efficiency
Powertrain 1.5 features a ability electronics module that supplies 33 percent more current to the motor. As Autoblog Green notes, pushing more current generates more heat, but rather than boost the engine’s cooling capacity — the easiest solution — it appears Tesla improved the transistors to reduce electrical resistance, and therefore heat.
Modifying the PEM requiring modifying the engine, which features redesigned terminals and lower resistance. It’s beefier, too, and provides 33 percent more torque at the thermal limit, Straubel writes.
Straubel says Tesla is aggressively checking Powertrain 1.5 on the dynameter and on the road. A Roadster with Powertrain 1.5 will go to Death Valley later that summer for thermal examining, and another will rack up 40,000 kilometers (about 25,000 miles) of low- and high-speed durability analyzing on a track.
“When all is said and done,” Straubel writes, “this evolution of our Powertrain system
results in a vastly improved overall product for our customers. We have
maintained the key performance targets while increasing efficiency and
durability.”
Those customers driving Roadsters with the two-speed transmissions will have their cars retrofitted to Powertrain 1.5.
Lots more pics and technical details on the Tesla Motors blog.
Photo: Tesla Motors.
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