Hitting the Books: How Tesla engineers solved the problem of exploding EV batteries

Between CEO Elon Musk’s usually erratic antics, strident competitors from present business titans, and a public that’s nonetheless not absolutely bought on the thought of touring by way of electrical cost, Tesla’s highway to prominence has not been a clean one. However dealing with a federal investigation into its driver help techniques, is much from the largest roadblock the corporate has navigated. As journalist Tim Higgins explains in his new e book, Energy Play, again within the early aughts, Tesla’s engineering staff needed to overcome a good more durable problem: protecting the primary iterations of its EVs from randomly exploding.

From the e book POWER PLAY: Tesla, Elon Musk, and the Wager of the Century by Tim Higgins, revealed within the US on August 3, 2021 by Doubleday, an imprint of The Knopf Doubleday Publishing Group, a division of Penguin Random Home LLC, and within the UK on August 5, 2021 by WH Allen. Copyright © 2021 by Tim Higgins.

A panicked letter from LG Chem arrived at Tesla with a dire demand: Return its batteries.

Simply as Tesla was proving it might craft a lithium-ion battery pack by itself, the battery business was grappling with the hazard that cells posed once they had been dealt with incorrectly. AC Propulsion had discovered this the arduous approach months earlier, in one in all an rising variety of incidents that despatched shudders by the battery business. En route from Los Angeles to Paris, a cargo of AC Propulsion’s batteries caught fireplace because it was being loaded onto a FedEx airplane whereas it refueled in Memphis, triggering an investigation by the Nationwide Transportation Security Board and prompting considerations about easy methods to transport batteries sooner or later. Private electronics corporations, equivalent to Apple Inc., had been recalling gadgets with lithium-ion batteries out of concern they may overheat and catch fireplace. In 2004 and 2005, Apple recalled greater than 150,000 laptops — with batteries made by LG Chem.

When LG Chem realized it had bought a lot of its batteries to a Silicon Valley startup that deliberate to make use of all of them for a single machine — a automotive, because it occurred — its authorized division despatched a letter demanding the cells be returned. The battery maker didn’t wish to be related to a doubtlessly fiery experiment.

[Tesla’s first CEO, Martin] Eberhard ignored the request. He had little selection. His wager that Tesla would have the ability to discover a prepared battery provider was proving tougher to cowl than anticipated. With out these batteries, there won’t be a second probability to get extra.

Amid all the consideration on lithium-ion batteries, [Tesla Co-Founder/CTO, JB] Straubel thought again to his former home in LA, the place he and [Tesla employee number 7, Gene] Berdichevsky celebrated the thought of an electrical automotive by setting cells afire. If struck with a hammer, they placed on fairly a present. Vehicles had been at all times at risk of that sort of affect, however there was additionally a extra insidious risk. He started to surprise what would possibly occur if one of many cells within the tightly packed cluster that might kind a automotive’s battery pack obtained too heat.

In the future in the summertime of 2005, he and Berdichevsky determined to search out out. With the workplace cleared out for the day, they went to the parking zone with a brick of cells — a cluster of batteries glued collectively. They wrapped one of many cells with a wire that might permit them to warmth it remotely. Then, from a secure distance, they flicked the heater on. The person cell shortly rose to greater than 266 levels Fahrenheit (130 levels Celsius), inflicting the battery to flash right into a blinding flame because the temperature spiked to 1,472 levels, then explode altogether, sending the remaining pores and skin of the battery into the sky like a rocket. Then one other cell within the pack caught fireplace, launching into the air. Quickly all the cells had been on fireplace. Bang. Bang. Bang.

Straubel acknowledged the implications of his beginner pyrotechnics. If an incident just like the one he cooked up had been to occur within the wild, it might spell the top for Tesla. The following day, after they disclosed their experiment to Eberhard, they confirmed him the scorched pavement, pitted with holes from the night time earlier than. Eberhard urged them to be extra cautious, however he couldn’t deny that extra testing was wanted. He gathered the staff at his rural home on the hills above Silicon Valley for extra experiments. This time, they dug a pit and put a brick of cells in it, then lined it with plexiglass. They heated one of many cells and once more the batteries ignited, inflicting a series of explosions. Straubel had been proper: this wasn’t good. They wanted exterior assist to know precisely what they had been coping with — the staff wanted battery specialists.

Days later, a small group of battery consultants had been gathered with what at first appeared like a manageable message: Sure, even the most effective battery producers produced a random cell that might have a defect, inflicting it to brief and catch fireplace. However the odds had been distant. “It occurs actually, actually occasionally,” one of many consultants stated. “I imply like between one in one million and one in ten million cells.”

However Tesla deliberate to place about 7,000 cells in a single automotive. Sitting close to Straubel, Berdichevsky pulled out his calculator and computed the probability {that a} cell in one in all their automobiles would possibly catch fireplace by probability. “Guys, that’s like between one in 150 and one in 1,500 automobiles,” he stated.

And never solely would they be churning out automobiles with faulty batteries that, if ignited, might set off a series response, however their automobiles might be detonating within the garages of the richest of the wealthy—burning down mansions and lighting up native TV information. The temper within the room shifted. The questions grew to become extra pressing: Was there something that might be performed to keep away from faulty cells?

Nope. Random cells had been at all times going to get too scorching and spark thermal runaway — principally an explosion sparked by overheating.

Straubel and the staff returned to their work deflated. The stakes couldn’t have been increased for Tesla. This wasn’t nearly fixing a tough drawback, one which threatened to empty restricted sources and derail improvement of the Roadster. In the event that they cast an answer that appeared to work, solely to see Tesla automobiles catch fireplace in years to return, the corporate could be doomed. And it will be a failure not only for Tesla; their goals of the electrical automotive might be set again a era. They may not solely trigger harm or loss of life, they may kill the electrical automotive within the course of.

In the event that they needed to actually turn out to be an automaker, they needed to face the problem that GM, Ford, and others had been coping with for 100 years: They’d to make sure they had been placing secure automobiles on the roadway. An answer to thermal runaway might quantity to a real breakthrough, one that might set Tesla other than the auto business for years to return. Utilizing lithium-ion batteries had appeared like a wise thought, one which a lot of thinkers had alighted on. However determining easy methods to use them with out turning the automotive right into a ticking time bomb might be their biggest innovation.

They stopped work on all points of the Roadster venture and shaped a particular committee to discover a answer. The staff arrange whiteboards, itemizing what they knew and what they wanted to be taught. They started working each day checks. They’d configure a battery pack with the cells spaced in another way, to see if there was a super distance for holding chain reactions. They tried completely different strategies of protecting the batteries cool, equivalent to having air circulate over them or tubes of liquid brush previous them. They’d take the packs to a pad utilized by native firefighters for coaching and ignite one of many cells to higher perceive what was going down.

The hazard of the scenario was pushed house whereas en path to a type of checks. Lyons, their recruit from IDEO, started to odor smoke coming from the again of his Audi A4, the place he had loaded a pack of check batteries. It was an indication {that a} cell was heating up and approaching thermal runaway. He instantly stopped and yanked the batteries out of the automotive and threw them to the bottom earlier than his automotive might catch fireplace — an in depth name.

Finally, Straubel started to slender in on an answer. In the event that they couldn’t preserve a cell from warming, possibly they may preserve it from reaching the purpose the place it set off a series response. Via trial and error, the staff realized that if they’d every cell lined up a number of millimeters from its neighbor, snaked a tube of liquid between them, and dumped a brownie-batter-like combination of minerals into the ensuing battery pack, they may create a system that contained overheating. If a faulty cell inside started to overheat, its vitality would dissipate to its neighboring cells, with no particular person cell ever reaching combustibility.

The place simply months earlier they’d been struggling to arrange a workshop, now they had been on to one thing totally new. Straubel was thrilled. Now he simply wanted to determine easy methods to persuade the battery suppliers to belief them. Straubel was listening to from Eberhard that the established producers weren’t excited about their enterprise. As one govt at a provider advised Eberhard: You guys are a shallow pocket. We’re a deep pocket. In case your automotive blows up, we’ll in all probability get sued.