Bill Arnett is a software engineer who envies Renaissance and Enlightenment thinkers – people who tried to understand a large fraction of all human knowledge. During an attempt to retire and spend more time on hobbies such as photography and astronomy, Bill decided to learn HTML by creating an astronomy site. It became so popular that it generated enough revenue through Google AdSense to pay for his Roadster. Another recent project was an iPhone application that simulates mechanical watches.
Bill says the Roadster is “exactly the car I've been dreaming about for 40 years.” Here is his description of his tour last month to Tesla’s powertrain installation facility, where he watched technicians assemble his car, Signature One Hundred No. 55.
On Nov. 12, I viewed the final assembly of my car in Menlo Park, Calif., immediately behind Tesla’s flagship retail store. The car had just arrived from the Lotus facility in Hethel, U.K., in “glider” form without a powertrain.
What interested me most was the installation of the ESS (Energy Storage System, or battery pack), the motor and the PEM (Power Electronics Module). These are the parts that make a Tesla a Tesla. Zak Edson also gave me one of the "18650" cells used in the ESS. One of the photos shows it next to ordinary AA, C and D alkalines.
Tesla’s service technicians had to do a lot of tweaking as the ESS went in, not easy since it weighs 990 lbs. The process took several minutes, including partial disassembly of the rear suspension so the ESS can clear the wells.
The ESS is held in place with only 12 bolts. Fine adjustments had to be made before the bolts were inserted to make the bolt holes align perfectly. They were very careful with those bolts – after all, they're carrying a third of the car's entire weight!
After the ESS went in, the rear suspension was reassembled and the shocks/springs installed. None of this seemed particularly high tech. Before installing the motor, they covered the ESS with an old piece of cardboard to prevent scratches as the motor is installed.
The drive shafts simply slip into spines in the wheels and the gearbox. First they're inserted into the wheels. Then they're connected to the gearbox as the motor assembly is lowered into the car. Then they're secured by a single nut on the outside of each wheel. That's the entire mechanical drivetrain: motor, gearbox, drive shafts, wheels. Very simple. Simple is good.
The motor installation went even faster than the ESS installation -- just a few minutes!
The ESS and motor had to be handled with hydraulic lifts but the PEM, which weighs 77 pounds, is easy for a couple of guys to drop in manually. They only major flaw in the Roadster is that the PEM completely hides the motor; I thought they should have made the covers transparent!
After the PEM was secured in place there were a dozen or so electrical connectors to attach, including three really big ones to the motor, the ESS and the charging port. Mating all those connectors took longer than installing the motor itself. Some of them are pretty hard to reach. It would have taken me hours. But the Tesla guys knew exactly how to grab each one just so, and I suspect there may have been a little design work to make that possible. :-)
Not until I got home did I consider another unusual aspect of electric vehicles: they're clean -- not just in the sense of being good for the environment but in the sense of not getting your hands greasy. The whole shop looked more like an electronics shop than an auto shop. The floors were spotless. Everyone's clothes were clean. It didn’t smell like an auto shop.
In fact, while the guys were working on my car, the brake rotors were covered by a rag. I assumed that was to protect the expensive rotors from accidents. But no, it was there to protect the workers' clothes from one of the few places where there's actually a bit of exposed grease! :-)
I am grateful to Stephen Smith, Robert Irvin and the rest of the shop crew for making this possible -- and for putting up with all my questions. This is something I've wanted to see ever since I ordered my Roadster more than two years ago.