Exclusive: At Least 100 Chevy Bolt Drivers Have Experienced Complete Loss of Propulsion

By · September 12, 2017

A battery pack is installed into the Chevrolet Bolt at GM’s Orion Assembly Plant.

General Motors yesterday confirmed to PluginCars.com that approximately 100 Chevrolet Bolt electric cars were equipped with faulty battery cells that left drivers stranded after experiencing a complete loss of propulsion while driving. In some cases, the loss of propulsion was nearly instantaneous—with the car quickly stopping and the driver not being able to drive forward or reverse out of harm’s way. Other drivers had up to about five minutes to maneuver to safety.

“I can confirm that less than 1 percent of Bolt EV customers have experienced an unexpected loss of propulsion as a result of the cell low-voltage condition,” wrote Chris Bonelli, coordinator of global advanced technology communications at General Motors, in an email. While the company has the ability to repair or replace individual modules within the Bolt’s pack, Bonelli indicated that GM had replaced the entire battery pack of affected cars that were transported to Chevrolet service centers.

Clarification: Faulty Cells Not Wrong Range Information

On Aug. 24, PluginCars.com reported that General Motors started notifying owners of the Chevrolet Bolt all-electric car that might have a battery problem that could leave them stranded. Those customers—General Motors clarified yesterday—are not the same as those who already experienced loss of propulsion, but an additional set of drivers who could be affected in the future.

At the time of the Aug. 24 report, Kevin Kelly, ‎senior manager for advanced technology communications at General Motors, told PluginCars.com that drivers were stranded because the dashboard range indicator provided a false reading of remaining range. Kelly said that, as a result, drivers ran out of charge because they were misled by the dashboard into believing there was remaining range when in fact the battery had run out of energy. It appears that the faulty cells were the cause of erratic and incorrect range numbers (rather than problems with the software and dashboard displaying inaccurate remaining range.) “We noticed an anomaly via data from OnStar and that led us to investigate the issue,” said Kelly.

Bonelli this week clarified that the problem is a “cell low-voltage issue” that became apparent after approximately 100 drivers experienced a loss of propulsion. In the email to PluginCars.com, Bonelli wrote, “The issue stems from the cells' voltage dropping, and we have made quality improvements along the supply chain to contain this to early production packs.” He confirmed that a pack's voltage could quick drop without activating a so-called limp mode before losing propulsion.

A 2017 Chevrolet Bolt after an unexpected battery problem that left the car disabled.

General Motors sources battery cells for the Chevrolet Bolt from LG Chem, a South Korean automotive supplier. The cells are assembled into packs by LG Electronics, which delivers fully assembled packs to GMs Orion Assembly plant in Orion Township, Mich., where they are installed into Bolt EVs. General Motors and LG Chem jointly establish standards and processes to ensure battery quality. The 60 kilowatt-hour packs each contain 288 individual cells. A small number of faulty cells—even a single cell—could lead to a loss of propulsion.

By addressing the problem of potentially faulty cells in an early period of cell production, GM believes that it has quickly identified and contained the risk. In addition to the 100 or so cars that already experienced a loss of propulsion, there are other cars—perhaps several dozen—that were identified via GM’s OnStar remote diagnostics as having a potential low-voltage problem. General Motors declined to provide the exact number for how many cars could be affected.

2017 Chevrolet Bolt EV battery pack and system

For General Motors, discovering which cars might have this problem is an ongoing process. More affected cars could be identified in the future, while some of the affected customers who were notified have not yet brought their Bolt in for service.

The primary means by which GM is identifying the cars at risk is via OnStar—analyzing remote data of vehicles on the road. “Through OnStar diagnostics, we are monitoring the condition of the chemistry within the battery pack, not specifically its range,” wrote Bonelli. “We are using a unique algorithm to determine how the condition of the battery may affect remaining range.” Some affected cars could still be on dealership lots—not yet sold to customers.

General Motors emphasized that not every single customer in an early production vehicle will experience the problem. Also, the company communicated that the number of affected customers—as a percentage—will decrease from the current “less than one percent,” to an even lower number. GM hopes that customers who have been contacted will quickly respond to avoid experiencing a loss of propulsion while driving.

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