By on July 23, 2021

Chevrolet has issued a statement to owners of Bolt EVs that could be subject to surprise fires while charging, offering more tips on how to avoid burning down their homes while it preps another recall. General Motors and supplier LG Chem have identified “two rare manufacturing defects” that they believe are causing the fires and are suggesting avoid charging their vehicles in an extremely specific manner until after the secondary recall has been conducted. 

While the initial recall just involved a software update, which often feels more like a way for automakers to buy time than a real solution, the new one will actually replace some hardware. Chevrolet is still recommending customers take their vehicles in for diagnostics and the original software fix. But it also plans on replacing defective battery modules and recommending actions to minimize the fire risk posed by Chevy Bolts from the 2017-2019 model years.

Parking your vehicle outdoors and away from other flammable objects remains sound advice. We would also suggest not storing anything of value inside the car while charging and watching that thing like a paranoid hawk until after a mechanical fix has been completed. However, Chevrolet had some additional, highly specific ways of reducing the likelihood of being the person in your neighborhood whose EV exploded.

If you own a 2019 Chevrolet Bolt, GM is recommending using the Target Charge Level mode and not surpassing 90 percent of the vehicle’s maximum charging limitations. While that’s likewise true for the other impacted models, it manufacturer suggests using Hilltop Reserve mode. Both settings are designed to keep vehicles from overcharging when you don’t need to and ultimately extend the life of the battery. But I bet nobody anticipated using them for this.

But here’s the kicker. In addition to never charging the vehicle past 90 percent, Chevrolet would also like customers to ensure Bolt batteries aren’t depleted below 70 miles of remaining range and attempt to recharge the EV after every use. It sounds like GM wants to keep these cars from spending any more time plugged in than absolutely necessary. Some EV batteries, especially those furnished by LG Chem, have been suspected of coming undone while charging for a few years now and this (along with the Hyundai Kona EV recall) has really pushed the matter in front of the public.

While pretty much every lithium-ion battery is capable of hazardous thermal runaway when overcharged or overheated, they’re supposed to possess fail-safe circuitry that shuts everything down when the voltage is out of whack. But these systems are useless if manufactured or designed incorrectly, occasionally resulting in extremely difficult to stop and sometimes explosive vehicle fires. We’re not exactly sure of what went wrong with the Bolt, though the circumstances seem highly similar to the uptick in charging-related fires we’ve seen over the last few years.

Fortunately, EVs aren’t supposed to catch fire with a frequency greater than internal combustion cars. But the brunt of the supportive data comes from outlets hoping to sell you an electric car, making some claims suspect. For example, Tesla has asserted that gasoline-powered cars are about 11 times more likely to catch fire than one of its models. There might be some truth to that, specifically when Tesla fires seem to be preceded by high-speed crashes that could turn any automobile to ashes. But we doubt other manufacturers are willing to make similar claims and there have been some studies that undermine the premise that EVs are less fire-prone.

In 2012, the National Highway Traffic Safety Administration (NHTSA) accidentally burned up a Chevrolet Volt during crash testing. It then ordered a trio of batteries to wail on, getting two of the three to catch fire. While this seemed damning, there’s not much to compare it against. The NHTSA typically preps gasoline-powered models without fuel during crash assessments and focuses on things like how flammable the interior materials are in smaller-scale tests. Frankly, we need more comprehensive research before anything can be proven. Electric and hybrid cars are still relatively new and there’s not been enough time spent examining the long-term implications of battery charging or how much abuse they can take before thermal runaway becomes an issue.

[Image: General Motors]

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16 Comments on “Hot Tip: Chevrolet Addresses Bolt EV Fires, Readies Recall...”


  • avatar
    EBFlex

    Remember when we were told that we have to drive EVs because we only have 10 years left on this planet and if we do the polar bears will grow and and the sea levels will drop to what they were a billion years ago and that they are so much simpler and safer than gasoline vehicles?

    What a crock

  • avatar
    jpolicke

    Well, so much for the whole “charge your car overnight so it’s ready in the morning” thing.

  • avatar
    aja8888

    I suspect GM will pay the home owners for relocating their Bolt charge equipment outdoors during all this recall stuff.

  • avatar
    Master Baiter

    “…they’re supposed to possess fail-safe circuitry that shuts everything down when the voltage is out of whack. But these systems are useless if manufactured or designed incorrectly…”

    Battery fires are almost never caused by a failure of protection electronics because there are multiple levels of redundancy. Fires are usually caused by internal cell shorts, which can happen whether or not the battery is being charged, although charging does place mechanical and thermal stresses that can induce a short in a poorly manufactured cell.

    • 0 avatar
      mcs

      @MasterBaiter: You’re 100% right. I just saw probably the best youtube video on battery tech and it’s current state to date. This guy really nails it: youtube.com/watch?v=fdSqibMhBwg

  • avatar
    conundrum

    I’m old enough to remember the superb quality Of Lucky Goldstar TVs and electronics. Crap is the description that comes to mind. Much like their world-renowned kitchen appliances and washing machines.

    Recently of course, LG has underbid all other battery suppliers to get contracts, including with VW and Mercedes, and been totally unable to deliver.

    Call it a bias on my part, but overly aggressive Korean companies of all kinds have never impressed me much. They are insatiably greedy, overly competitive and willing to promise anything to get a deal signed. As I see it.

    No wonder many of the existing car companies now want to build their own gigafactories, and dump the underperforming overpromising LGs of this world

    GM, of course, as with their stock-price-boosting charade of Supercruise (to impress the technical dunces of Wall Street) for trailering with pickups, plus their reliance on LG for Ultium, are not much better. If at all.

    • 0 avatar

      Wait for TTAC patrol to show up to convince you how wonderful are cars made by Huyndai/Kia.

    • 0 avatar
      wolfwagen

      Maybe in the past.
      However, out of the appliances that came with my home when I bought it (LG Range, Samsung Fridge, GE Microwave, and Samsung Dishwasher), My LG has been flawless. (knocking on wood). My Samsung Fridge, I would love to set my Samsung Fridge on fire and then throw it in a volcano. However, I’m sure the damm thing will continue to freeze up. Samsung Dishwasher was replaced by another Samsung and then a Kitchen Aid

  • avatar
    ToolGuy

    Overview of vehicle fires in the U.S.:

    https://www.nfpa.org/-/media/Files/News-and-Research/Fire-statistics-and-reports/US-Fire-Problem/osvehiclefires.pdf

    Interesting factoid: Roughly 1 out of 6 fires reported to U.S. fire departments are vehicle fires.

    “Highway vehicle fires per billion miles driven” are down by a factor of 5 since 1980 (but relatively level over the past decade).

  • avatar
    SCE to AUX

    The issue is a bent anode tab that occurred in manufacturing. The tab can short when in a high charge state because of the dimensional growth that lithium ion batteries experience during charging.

    This really isn’t an EV thing. Those cheap knock off replacement batteries for your cell phone could also have mfg defects, and apparently millions of other cars with safety defects.

    GM is not going to avoid replacing these batteries.

  • avatar
    mcs

    @MattPosky: Great article!

  • avatar

    This is yet another reason not to buy the Bolt. Then again not many people are buying them anyway.

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