Are Electric Car Batteries Getting Too Big?

By · September 12, 2018


The Porsche Taycan is one vehicle in a new breed of big-battery EVs.

Electric cars don’t have enough driving range. That’s been the reason, according to conventional wisdom, why EVs are not purchased in higher numbers. And it’s the reason that automakers—starting with Tesla—produce vehicles packed with giant battery packs capable of storing as much as 100 kilowatt-hours of energy. The race for big-battery EVs now includes the Chevy Bolt and Hyundai Kona EV (both with 64 kWh packs), as well as 95 kilowatt-hour batteries carried by the Jaguar I-Pace and Porsche Taycan.

These big-battery EVs solve the range problem by providing as much as 300 miles of driving on a single charge. However, it is now dawning on automakers and analysts that bigger is not always better when it comes to EV batteries.

According to a study released today by Ricardo, the British auto supplier and research firm, one of the unintended consequences of large batteries is greater environmental impact. It’s a matter of looking not only at tailpipe emissions but the total lifecycle for carbon. Ricardo states that the well-to-wheel CO2 emissions of current electric vehicles are significantly lower as a proportion of full lifetime emissions than those of typical current passenger cars. And EVs will become even cleaner as the grid uses more renewables. But the firm warns: “If a race for bigger and bigger batteries is left unchecked, EVs doing low mileages could undermine some of the potential benefits.” Reminder: Americans drive, on average, fewer than 40 miles per day.

Andy Eastlake, the managing director of the U.K.’s Low Carbon Vehicle Partnership, which sponsored the Ricardo study, said, “Vehicle electrification using ‘right-sized’ batteries should progress hand-in-hand with low carbon fuels and energy and production innovation, to deliver the biggest greenhouse gas savings across the whole road sector.”

The new Ricardo study echoed what Tony Posawatz—the former line director for the Chevy Volt and chief executive of Fisker Automotive—wrote in July for Forbes. His piece was entitled, “Mine Is Bigger: Why Larger EV Batteries Are Not The Answer.”

Less Is More

Poswatz says that the solution to so-called range anxiety can’t always be “just adding more and more battery energy to the vehicle to match some conventional internal combustion engine vehicle range with a large gas tank.” According to Posawatz, there are consequences to bigger batteries: more cost, more mass, and longer charging times to top off.

He poses this provocative question: “Do we want to carry around all that extra battery everywhere we go just for those occasional longer distance trips? For a 60-kWh EV battery, the size and weight required to get about 225 to 250 miles of EV range on a single full charge, the pack weight comes in at nearly a half-ton of battery.” His most pointed critique is aimed at the even larger packs now approaching 100 kWh—an expensive and impactful asset that must be hauled even it’s barely used.

Instead, he advocates for taking more cost out of EVs to increase their profitability, as well as rethinking the entire EV ecosystem.

Don Tappan, vice president of Braemer Energy Ventures, told Design News last month that engineers are already re-thinking EV battery size—because the core nature of vehicle ownership is being shaken up in our age of shared, connected mobility. Tappan said that today’s commuters want options beyond owning a car—including ridesharing and living a walkable distance from work.

“If you want to have a big battery that can solve 99.9 percent of your use cases, it can get very expensive, and your battery capacity can be underutilized,” said Tappan. He underscores the wide array of emerging transportation use cases. “Automakers will need to be aware that some use cases may require EVs with big batteries, while others call for medium-size batteries and still others need small batteries combined with internal combustion engines.”

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