On May 1 a Chevrolet Bolt caught fire while sitting in a garage in Ashburn, Virginia. Fortunately nobody was harmed, but the fire badly charred the owner’s home and vehicles.
At the time the incident occurred, we didn’t know what the state of the Bolt was, whether it had been updated to the latest fire risk-mitigating software or if it had any sort of accident history that might’ve made it more susceptible to going up in flames.
Thanks to an interview with the owner published late last week by Electrek, it would seem the car was in excellent condition with some of the battery software updates installed. In a brutally ironic twist, the owner actually received the notice for the most recent recall in the mail mere hours before his Bolt combusted, according to the story.
The Bolt was reportedly charged from less than 30 miles of range remaining to 160 miles just before the incident — roughly 60 percent of full capacity and 100 miles shy of the 260-mile peak range General Motors advertises. The owner says he was careful to never fully charge his car, a practice GM recommended to customers after the first Bolt fires were reported.
All in all, the Bolt did $235,000 worth of damage to the owner’s property — a tough pill to swallow, but his family was safe. It marks yet another incident where an EV — one with a recall history, no less — spontaneously caught fire, even with a charge-limiting update applied.
Hyundai’s Kona Electric faced a similar problem that Hyundai initially dealt with in a similar way: by updating software to cap peak charging, as the strain of full energy storage is particularly damaging to lithium-ion batteries. But the fires still occurred, forcing the automaker to take the Kona Electric off the market in South Korea earlier this year and replace the batteries in affected vehicles. Both the Bolt and Kona incorporate batteries manufactured by LG Energy Solutions.
It’s important to note that this isn’t indicative of an epidemic of EVs exploding left and right. When GM announced the Bolt’s first battery software recall last November, it stated five cars between model years 2017 and 2019 had caught fire of about 70,000 Bolts on the road at the time. Supposedly, two more have been added to that list since. Nevertheless, manufacturers need to take any fire risk seriously — especially electric fires, which happen very fast and are very hard to put out.
GM recently said it’s finally settled on a “permanent” solution for the Bolt’s issues that, once again, involves more software to fix a problem confirmed to be caused by a physical manufacturing defect. From The Detroit News:
GM’s experts concluded a “rare manufacturing defect in certain battery modules in vehicles from these production years” led to the fires, GM spokesman Dan Flores said in a statement to The Detroit News. That defect could cause “a heat source or a short in a cell, which could propagate into a fire.”
To fix the issue, the automaker created tools for “dealers to diagnose battery issues as well as advanced onboard diagnostic software that, among other things, has the ability to detect potential issues related to changes in battery module performance before they become potential problems during vehicle operation and charging,” Flores said.
It sounds like GM engineers have figured out a way to gauge early warning signs and spot the possibility of something going wrong before it does. That’s great. Unfortunately, I’m skeptical how much good more monitoring will do between ordinary service intervals. I suppose time will tell how many fire-prone cars GM catches before they suffer a crispy fate.
I’ve been curious how adequate these software-based fixes are, as opposed to full battery replacement which ostensibly seems like the safest, albeit far pricier solution. So I reached out to Adam Tallman, GM engineer and former adjunct professor at Lawrence Technological University in Michigan, to get an answer. (Emphasis Adam Tallman):
The big issue with the batteries in question is something called dendrites. As these form they are the leading cause of Li-ion battery fires, these have a much higher chances of forming at high temperature and high State Of Charge (SOC). Limiting the SOC and modifying the charging rates through a software fix can prevent the growth of dendrites if you get the new calibrations right. What a software fix cannot do is get rid of dendrites that have already formed and are, for lack of a better term, a ticking time bomb.
The second thing to keep in mind is that these fire are almost always a chain reaction. One cell will not engulf the whole car or burn down the garage. The other thing that you can do via software is change how the vehicle responds to one cell going into thermal runaway (normally resulting in fire). If you can keep the other cells from going into runaway (called thermal propagation) then you can safe the vehicle, though your car would need a new battery and would not be drivable until it was replaced.
I am not 100% familiar with what changes GM or Hyundai have made, so I can not speak to if the software changes will or will not work, but if they were done right, (and that may or may not be possible depending on hardware limitations) you can save most of the batteries/cars.
Software can be enough provided the big qualifier Adam mentions above — when calibrated properly. Carmakers would obviously much rather address those issues through code, rather than spending the money to replace batteries on each car in a massive recall. They’re businesses, I get it.
That said, this is also a matter of life and death. Owners and their families can’t afford a company getting it wrong over and over again, even if only a small percentage of vehicles are in danger. At a certain point, the recall and replacement route might be the only rational option, out of consideration for the safety of your customers. Frankly, I don’t care how much that costs, whether the carmaker or battery supplier foots the bill, or if the government needs to twist executives’ arms to make it happen. But after enough failed attempts, it probably needs to.
Have we reached that point with the Bolt yet? I suppose that’ll all depend on how good GM’s latest measure is. If it’s not up to task, maybe the company shouldn’t get another pass.