Electric cars: Battery caching, navel gazing, and community buildingCMU robotics prof Illah Nourbakhsh unveiled ChargeCar today, a project to redesign electric cars for urban commutes. He prefaced it by recounting all the times he's been in his own electric car, a RAV4EV, driving 70mph by the airport when he'd hear an NPR interview lamenting that electric cars just aren't able to go highway speeds or be dependable for long trips. He's also never visited a mechanic; no scheduled maintenance because the system is so much simpler, and regenerative braking means the motor does most of the work, rather than the brake pads. In eight years, he's only replaced the tires. (Though he can't pass PA emissions testing: You need a tailpipe.)
ChargeCar is based on the idea that hilly, stop-and-go, traffic- and coffee-detour-ridden urban commute is ideal for electric motors (and sucky for gas ones), but not for electric batteries. Batteries can't handle the constant changes, and have trouble regulating thermal processes when they're under heavy load. So, he treats them like a database and adds a caching layer: a low-voltage supercapacitor, which changes current direction easily but has lower energy density. Then he tries to hit the capacitor rather than the battery whenever possibly (charging when braking, and discharging to accelerate).
Okay, so battery caching is awesome. But the project also focuses on harnessing the power of communities:
- Communities of commuters submit .gpx data from their daily drives to the site. (Is there an iPhone app in the works?) In return, they get personal informatics about their commute efficiency, cost, and carbon footprint. And how much they would save (in real cash money) if they'd been driving an electric. Could be used to pit neighbors against each other, à la this California MUD's social comparison energy bills.
- Communities of hackers. They've released the totally naive controller algorithm (always hit capacitor first, then battery) as open source in Ruby. Hackers are encouraged to submit better algorithms. One of them will win an electric car. And über bragging rights.
- Communities of mechanics. Pittsburgh is full of good mechanics and metal shops. One chop shop owner gutted the engine, gas tank, and transmission from a Toyota Scion demo car for free (the parts were worth more to him than his time) so the researchers could fill it with their own electric engine and batteries. ChargeCar would foster a community of mechanics to recycle cars (like Cash for Clunkers, eco-style).