Whenever it comes, an influx of millions of electric vehicles on the nation's roads will bring with it new safety challenges.
Battery behavior remains a vexing subject, one that mechanics and first responders to collisions will need to be well versed in. But the industry need not wait until the electric future arrives to make such preparations.
Lessons learned about battery safety proliferate. Here's a quick rundown of some past and present safety challenges related to batteries and how they've been handled.
Catching fire, then attention
It was the fire that awakened the industry and federal safety regulators. Three weeks after a government crash test in May 2011, a fire started in the lithium ion battery of a Chevy Volt.
A subsequent investigation revealed the battery compartment had been penetrated, and the battery's liquid cooling system ruptured. Starting the next year, General Motors made structural changes to better protect the Volt's battery packs.
But at the onset of an era of plug-in hybrid and battery-electric offerings, the National Highway Traffic Safety Administration (NHTSA) wanted to know more. In the months that followed, the agency crash-tested four more Volts and conducted impact tests on six Volt battery packs. Three separate tests resulted in a "sustained fire," per a report.
Though the agency cautioned that the conditions that caused the initial fire were never replicated, the testing results showed the potential for fire hazards to develop, sometimes weeks after crashes, with little to no warning.
Monitoring drivers for fatigue and distraction has been an important component of driver-assistance features. But now there may be more attention turning to battery-monitoring.
Years after those Chevy Volt fires, keeping an eye on individual cells could help avoid such thermal-runaway instances, which occur with little or no warning.
"That's the issue; we need to monitor them," said Anna Stefanopoulou, director of the Energy Institute at the University of Michigan. "We need to monitor cell activity and interrogate them to know how they're doing and what they're doing."
787 Dreamliner grounded
The potential concerns of lithium ion batteries aboard aircraft became all too real when a short circuit in a battery aboard a Japan Airlines flight in 2013 resulted in a thermal runaway that began in one of the battery's eight cells and spread to the adjacent cells. The incident led to a temporary grounding of the fledgling 787 Dreamliner fleet.
A subsequent investigation conducted by the National Transportation Safety Board (NTSB) found that shortcomings in both design and certification processes led to the fire. Boeing had ruled out the possibility of cell-to-cell propagation during development, and as a result, "thermal runaway was not thoroughly scrutinized by Boeing and FAA engineers," an NTSB report found.
Among the 15 safety recommendations the independent agency sent to the Federal Aviation Administration (FAA), Boeing and battery supplier GS Yuasa: Require manufacturers to demonstrate acceptable performance as part of the certification for any aircraft that incorporates permanent lithium ion batteries.
Experience counts for something
EVs might necessitate a shift in the way firefighters battle certain car fires. But Michael Gorin, emerging issues program manager at the National Fire Prevention Association, emphasizes they're not creating new risk."I would not say an EV fire is any more challenging or dangerous than a fire in a car with an internal-combustion engine," he said. "It's a different set of tactics."
First responders have plenty of experience with vehicle fires, which number an estimated 171,500 every year on U.S. roads, according to the National Fire Data Center, a division of the Federal Emergency Management Administration. About one in eight fires that fire departments respond to is a highway vehicle fire, the agency says. That doesn't include fire department responses to collisions.
To be continued
The next chapter in battery safety may be written by NHTSA. Last month, the federal agency began a probe of an "alarming number of car fires that have occurred worldwide" in Tesla Model S and Model X vehicles.
Investigators zeroed in on software updates to the battery management systems. They've asked Tesla to provide responses related to updates and their impact on charging rates, charging capacity and thermal management during and after charging.
Tesla's ability to make software tweaks to batteries and other vehicle systems via over-the-air updates remains unmatched in the industry. NHTSA's investigation seems to ask whether such software versatility creates unintended battery-related consequences.
Responses from Tesla are due at the end of November.