Andrew Moseman has covered science, technology, and transportation for publications such as The Atlantic, Inverse, Insider, Outside, and MIT Technology Review. He was previously digital director of Popular Mechanics and now serves as online communications editor at Caltech. He is based in Los Angeles. Read MoreRead More
EVs Are Too Heavy. Can They Get Lighter?
Electric vehicles are heavy because batteries are heavy. But building a lighter battery is no easy feat.
The transition from gasoline to electric vehicles will be a massive one in more than just a metaphorical sense. EVs have a weight problem — one that could undo some of the good created by going electric and exacerbate a bunch of cascading problems.
Electric vehicles are heavy because batteries are heavy. There’s just no way around it. The lithium-ion packs in EVs are the state of the art in modern battery technology and can store far more energy in a given amount of space compared to other rechargeable battery types such as nickel-cadmium. But their energy density still pales in comparison to gasoline. So, giving a car hundreds of miles of driving range means slinging a huge, heavy battery along the bottom of the vehicle.
A simple way to see the difference is between two versions of the same vehicle, one electric and one not. Depending on the various configurations, the Ford F-150 Lightning EV outweighs the gas-powered version of the pickup by at least 1,000 lbs., and sometimes closer to a full ton. Differences aren’t always so dramatic, but adding a giant battery, even when it means losing a bunch of internal combustion components, typically inflates weight.
Electrics are also heavy because all cars are heavy. The story of the last half-century of the auto industry is the death of smaller passenger cars, with consumer preference and regulatory loopholes having now led to the utter dominance of SUVs and trucks. In the EV market, smaller and lighter vehicles like the Tesla Model 3 and Chevy Bolt sold in decent numbers by hitting the market early and meeting the car-buyers who don’t want a giant ride. Now, though, the EV space is going the same way as gas. With American car-buyers willing to pay more for the crossovers and pickups they desire, automakers are moving away from less profitable modestly sized EVs in favor of crossovers and pickups.
It adds up to a lot of extra bulk rolling down the streets and highways. The most pressing danger from all these oversized electric vehicles is the threat they pose to anybody outside the car. The extra mass, combined with additional safety tech that can be built into places where engines and hoses used to go, means a big EV’s passengers are inside a fortress. It’s not such good news for pedestrians, cyclists, and occupants of any vehicle that’s not a multi-ton tank. Pedestrian deaths, which had been declining for years, began to climb again in 2010 and have reached their highest point in 40 years. It’s more difficult to see out of our increasingly huge vehicles, and when accidents happen, they are deadlier.
That’s not the only weighty concern. Over time, heavy vehicles cause more damage to roadways, bridges, and other driving infrastructure, and require them to need maintenance more often — causing even more of those pesky construction zones that slow highway traffic. At the same time, electric vehicles don’t pay for gasoline taxes that fund road maintenance, something economists are trying to solve, fast. EVs and other new vehicles are so hefty, Slatereports, that those auto-hauler semi-trucks — the ones you see on the interstate ferrying a bunch of cars to their new homes — can carry fewer cars at once because of overall limits on their cargo weight.
There is also the question of energy use. The relative fuel efficiency of electric cars is a rarely discussed part of the discourse about climate, cars, and energy. Perhaps that’s because EVs don’t come with a handy metric everyone is accustomed to, like miles per gallon (EVs can deliver an equivalent, or Mpg-e, but it’s a murky number that requires some math). Perhaps it’s because so few Americans drive electric — or because the focus, from a national perspective, has been on convincing as many people as possible to go electric, even if it means selling them a war machine like the GMC Hummer EV.
But not all electric cars are created equal. Using its imperfect data, the EPA rates a smaller electric sedan like the Tesla Model 3 at about 140 Mpg-E. For bigger SUVs, that figure falls under 100, and as low as the 60s for the Porsche Taycan or the fully loaded F-150 Lightning. That mark is still better than what you could get from an ordinary gas or hybrid car. However, it means you’re using roughly twice as much energy to run errands in an Audi E-Tron as in a Chevy Bolt. From a climate perspective, we’re giving away much of the good of transitioning to electric cars by selling bigger, bulkier, more inefficient ones.
It’s not clear there’s an immediate fix to this problem. Carmakers will sell what car shoppers want to buy. Most Americans clearly want big vehicles, and no amount of climate scolding will change that. To convince car buyers who are already wary of range anxiety to switch to electric, new vehicles need as much range as they can get — and that means packing as much battery as possible into the bottom of the car.
Are lighter EV batteries the solution, then? Well, lowering a car’s power-to-weight ratio has been an automotive obsession since the dawn of the industry, because getting more power from less weight makes a vehicle zoom-ier. As the industry transitions to electric power, lots of auto engineers are now focused on squeezing more juice out of batteries, while researchers like Kimberly See at Caltech experiment with new battery chemistries that could, one day, perhaps supplant the lithium-ion cells of today. [Editor’s note: Caltech is where I do my day job.]
It’s a tough problem, See told me. Some ideas for alternative battery chemistries potentially can store more energy per unit of mass, but their design is nascent compared to that of lithium-ion, which has been developed since the 1990s. Building an actual working battery always involves trade-offs between weight, safety, and power — and weight can’t always win.
“There are chemistries out there, like Li-S [lithium-sulfur], that would make packs much, much smaller,” See says. “But there are many fundamental science challenges.”