The Chevrolet Bolt EV and EUV electric cars remain on a production pause, but GM confirmed Monday that battery production is again underway.
Production has resumed at LG battery plants in both Holland and Hazel Park, Michigan, the automaker said, as LG understands the nature of two manufacturing defects that have been the root cause of Chevrolet Bolt EV fires—and a resulting recall that appears bound to be GM’s costliest ever.
The companies have identified the two unrelated manufacturing defects, a torn anode and a folded separator, which need to be present in the cell simultaneously in order to potentially cause a fire.
“Interaction between the two is what causes the issue,” explained Tim Grewe, GM global electrification and battery systems director.
2017 Chevrolet Bolt EV
LG and GM have been working together in recent weeks, amid the pressure of a production pause, and LG has implemented new manufacturing processes, incorporating those insights, to avoid the defects, GM says. The automaker plans to do increased cell-level reviews and spot-checks in the future to build back confidence in the batteries. Grewe explained that engineers are assuring not just that such issues don't happen with the new, unrelated, larger-format Ultium cells GM and LG will be making under their Ultium Cells LLC joint venture, but that GM applies its manufacturing engineering expertise to be on the lookout for other potential issues.
GM hasn’t yet provided an update on when production of the Chevrolet Bolt EV and EUV will restart. It confirms that production will be paused at least through the week of October 11.
The company is aware of 13 suspected battery fires that have been investigated as possibly linked to the issue.
In the meantime, GM will be flashing a new software update to affected vehicles. That will effectively drop the maximum state of charge to 80 percent, gradually easing the state of charge back to 100 percent if the battery pack continues to pass certain diagnostic tests.
After the software update, available within 60 days (likely then by mid November), customers will again be able to park and charge in the garage, GM says.
2020 Chevrolet Bolt EV review update - Portland OR
GM continues to advise customers who haven’t received that latest software update not to charge above 90 percent state of charge, not to let remaining range drop below 70 miles, and not to charge indoors overnight. However it’s updated last week’s advice of staying 50 feet away from other vehicles to leaving “ample space” around the vehicle.
The company maintains that it will replace all the cells and modules in 2017-2019 Bolt EVs, but in an update Tuesday it wouldn’t provide an estimate of how many vehicles’ packs—such as those from newer model years—it might effectively replace in the end. There are nearly 78,000 Bolt EVs in the U.S. and Canada from those years, including batteries made in both Michigan and South Korea; adding more recent 2020-2022 models (plus remaining 2019s), in the expanded recall announced in August, brings the total to about 140,000.
2017 Chevrolet Bolt EV
Module replacement to the 2017-2019 models, as planned, will give those models the updated cells with higher energy density, as given to the 2020 Bolt EV, potentially boosting range significantly. That's because those early models' original 60 kwh will be upgraded to today’s 65 kwh—and range, unofficially, from the original 238 miles to something of the order of today’s 259 miles. GM emphasizes that these replacements will include all new modules and an eight-year, 100,000-mile warranty.
Both the specific build window of the vehicle and driving/charging patterns that involve deep discharge are factors that influence risk of fire, GM said, and it will be looking at those two details as it determined how it calls models back for the cell and module replacement. It will be revealing more information about the diagnostic software, and priorities for battery replacement, in the coming weeks.