Fully Charged

EV companies are figuring out ways to turn a car's frame into a giant battery, making their vehicles cheaper, roomier, and able to go twice as far.

- By Mark Andrews

"The ultimate battery pack would be one that consists of 100 percent active material. That is, every part of the pack stores and releases energy," says Euan McTurk, an electrochemist at Plug Life Consulting. That's because weight is one of the biggest challenges for EV engineers.

Simply plopping in a larger, heavier battery is not a surefire way to increase range. A heavier car requires bigger brakes, bigger brakes require bigger wheels, and the increased weight of it all requires a stronger overall structure. It's what car designers call the "weight spiral"-the bigger the battery, the more dead weight you have to lug around, which can eat away at any potential gain in range.

Traditionally, EV battery manufacturers have used cell modules that are connected and then placed in packs. According to Richie Frost, founder and CEO of electric-vehicle technology company Sprint Power, "standard modules may fit well within one pack but leave large areas of wasted space in another." Wasted space equals dead weight.

That's why Tesla and Chinese companies like BYD and Contemporary Amperex Technology (CATL) are working on designs that allow batteries to be more efficiently and densely distributed inside the car, getting us closer to that hypothetical ultimate battery pack. The new approaches stand to change the way EVs are produced, boost their range, and lower manufacturing costs.