Building the 2010 Chevy Volt: TheCarConnection Gets the Inside Story

April 3, 2008

It began innocuously enough: a brainstorm by General Motors’ car czar, Bob Lutz, in February 2006, set folks at the automaker’s design studios scrambling to come up with a “car of the future.” Initially dubbed iCar, the early sketches gave it wings, and took away its wheels. But what Lutz actually had in mind was a bit more down-to-earth, if equally difficult to achieve.

What the septuagenarian executives actually envisioned was an electric vehicle, one that could handle a typical motorist’s daily commute purely on battery power, but switch on a gasoline engine for longer trips. That would eliminate the fundamental problem of previous EVs: limited range.

Within months, things were falling into place, and in January 2007, GM stole the annual Detroit Auto Show when it unveiled what had been renamed the Chevrolet Volt. Initially presented as a pure concept vehicle, GM officials changed directions, a few months later, announcing plans to put the “extended-range electric vehicle” into production sometime in 2010.

In the slow-moving automotive world, that’s lightning fast, taking Volt from concept to production in barely four years – all the more amazing when you consider the amount of invention required to make the original prototype viable. True, there are plenty of hybrid-electric vehicles on the road today, but a production Volt will spend much, perhaps the majority of its time, running solely on electric power. And it will rely on advanced lithium-ion batteries that have never been scaled up for such large applications – nor put to the test under the wide range of conditions the typical automobile faces.

A day-long tour of the various Volt labs and studios, at the General Motors Technical Center, in Warren, Michigan, reveals a bee-hive’s level of activity, hundreds of designers and engineers pushing prototype lithium batteries to their limits; driving “mules,” or prototype vehicles, to see how they handle in real-world situations; and completing the final details on the production Volt’s interior and exterior design.

As The Car Connection previously reported, there’ll be some significant changes in the design of the 2010 Volt, though, chief designer Bob Boniface insists “It (has) to be true to the show car.”

The problem is that the show car performed better in wind tunnel testing, according to Lutz, running backwards. That’s bad news, because just modest problems with aerodynamics can have a big impact on the range of a battery car, and even in slower, around-town driving.

Carefully lifting the covers to show the front and rear corners of a near production-ready Volt, some changes are obvious, and in fact, some of the show car’s design features have been flip-flopped. The angular front fenders have been rounded off, so air will flow smoothly along the body. The rounded rear of the concept Volt, on the other hand, is now angular and hard-edged, also to improve wind flow.

While much of the car remained under cover, it was apparent that the latest remake of the Volt features a slightly shorter hood, and there’s a bit more wedge to the overall stance. More subtle details, such as mirrors and grille have also been tweaked for aerodynamic improvement.

What will it all mean? While GM officials were cautious about specifics, they suggested that cheating the wind more effectively could boost Volt’s City-cycle range from 40 to as much as 44 miles, solely on battery power. On the EPA highway cycle testing, EV-only range would jump from 37 to 43 miles.

Notably, Volt would still have unlimited mileage once its internal combustion engine would kick in. The vehicle will be a so-called serial hybrid. Current hybrid-electric vehicles, such as the Toyota Prius, use parallel powertrains, where the wheels can be driven by their electric motors, internal combustion engines or both, together. Volt’s IC engine will only be used as a generator. When the batteries are low, it will automatically start up, helping recharge the batteries and, if needed, also providing additional electric power to the plug-in hybrid’s battery pack.

That battery pack is the heart of the Volt, and the most worrisome part of the project. GM chose lithium-ion because of its high energy density; it stores about four times as much power per liter as the lead-acid cells used in the old EV1 electric vehicle. Higher-density batteries mean less weight – 375 pounds versus EV1’s 1200 – and a smaller footprint, so Volt will feature comfortable space for four rather than EV1’s cramped two-seater configuration.

Initially, GM planners explored more than 30 battery systems, settling on two suppliers, CPI and A123. The latter maker’s technology is already in widespread use – among other things on portable Black & Decker tools – but ramping up from handheld devices to Volt’s T-shaped pack is a daunting challenge.

That’s why GM engineers are putting bother CPI and A123 batteries through torture testing, both on the road and in a variety of lab settings designed to simulate the worst a consumer – and the weather – might through at the Volt. So far, a Malibu equipped with a prototype Volt drivetrain is living up to the challenge.

“On Day One, the vehicle started and it hasn’t been down since,” boasts Micky Bly, who oversees battery and control systems on the Volt project.

But there’s a lot more testing to do. By the time the plug-in hybrid is ready for production, GM needs to be absolutely certain each battery pack will be able to last for a grueling 150,000 miles or 10 years on the road.

We’ll have more behind-the-scenes news on the Volt tomorrow.

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