It is a simple matter of electrochemical reality. Lithium Ion Batteries grow “dendrites”; little spikes of lithium, that eventually short out the cell. Then some of them burst into flame. It’s what they do. This can be slowed down by never discharging fully, leaving 20% or so of the battery unusable, or by not charging when it is too cold, or hot, or charging it very very slowly since fast charging promotes this too.
But what you can’t do is have it never ever happen. (Unless you change to a less power dense battery chemistry and lose a lot of range).
The end result is that, after enough years, or with some (sometimes minor) physical damage, your car bursts into flames.
General Motors has now figured this out:
GM’s $2 billion Chevy Bolt fire recall casts shadow over electric vehicle market
Paul A. Eisenstein
Mon, August 23, 2021, 1:10 PM·3 min read
General Motors has expanded the recall of its Chevrolet Bolt electric car because of concerns about potential battery fires, adding 73,000 more vehicles, for a total of about 142,000 cars — every single one that Chevy has sold so far.
The combined cost of the recall will reach nearly $2 billion as the auto industry plans to roll out dozens of new electric models over the next 24 months to meet President Joe Biden’s goal that electric vehicles reach 50 percent of total U.S. sales by 2030.
GM’s EV lineup includes the launch of its electric Hummer pickup and an all-electric Cadillac Lyriq, which will use a different battery technology from the Bolt’s. The problem appears to involve manufacturing defects that can cause the batteries to short-circuit, even when parked.
No, “the problem” is why everything from laptops to cell phones (even Apple) to powered skate boards to Vape Pens and more have burst into flames from time to time. The best power density Lithium Ion cells like to grow dendrites of lithium if you charge and discharge them a lot, deeply, too fast, or at temperatures they do not like well.
It’s not the only manufacturer that has had to deal with EV fire problems. Hyundai has recalled about 90,000 of its Kona EV models because of what it said this year was the “increase[d] risk of a fire while parked, charging and/or driving.”
The problem with the Kona appears to have been the same as what ails GM’s Bolt models: manufacturing defects involving batteries supplied by LG Chem, one of the largest manufacturers of lithium-ion technology. The South Korean supplier’s shares took a sharp hit Monday in the wake of the Chevy announcement.
Other manufacturers, including the EV giant Tesla, have found themselves in the news because of battery fires. In December, a home in suburban San Diego was destroyed when a Tesla Model S caught fire as it was charging in the garage. Investigators blamed a faulty thermal management system designed to keep the battery pack cool.
Still, the coverage of EV fires may be overblown, said Sam Abuelsamid, lead auto analyst for Guidehouse Insights. Seven Chevy Bolts have caught fire, or about 0.006 percent of those on the road. By comparison, the National Fire Protection Association said 212,000 gas and diesel vehicles caught fire in 2018, or about 0.07 percent of those on U.S. roads.
“Yes, we’ve seen some battery fires, but the numbers are small, and they need to be put into perspective,” Abuelsamid said.
The longer a battery stays in service, the greater this risk becomes. It is proportional to charge / discharge cycles and depth of discharge. It is no surprise that the largely new batteries in the current fleet have a low percentage of burnup. But just give it time… Dendrites grow slowly over years if you have very good battery management (keep batteries in a narrow temperature range, never discharge below about 20%, never over charge, don’t charge really fast, etc. You know, all the things most folks don’t do…)
What we ought to be hearing about is the number of cycles to burnup and the number of years to burnup. Knowing WHEN to replace the battery before that point is what matters.
A very well designed battery will last longer than the rest of the car before it reaches that point. OTOH, I’m driving a 42 year old car (fine Diesel Mercedes) not a “5 years and rusted out” thing like they have Back East… so no EV for folks who like old, classic, or well used cars… In my opinion, of course.