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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