I think about the health and range of electric vehicle batteries every day. That means big battery recalls, like the one GM announced for the Chevrolet Bolt 2 years ago this week, are of particular interest to me and my battery nerds. Changing batteries in general raises an important question for electric cars: is the odometer a good indicator of vehicle value? A Bolt with 50,000 miles and a spare battery is as good if not better than new.
My team of battery scientists have been closely following and reporting on the Bolt recall since it was first announced in November 2020. Every day, over 1,600 Bolt owners monitor their EVs with Recurrent, and this data gives us insight into how their batteries are performing before and after replacement.
The origins of the Bolt battery remember
In November 2020, Chevrolet issued the first Bolt recall for the 2017 through 2019 Bolt model years after a handful of seemingly unrelated fires. The company instructed owners to limit charge capacity to around 90% and take the cars to a dealership for diagnosis and possible battery module replacement. Using driver data, we found that 16% of owners stopped charging to 100% in response to the safety prompts.
In July 2021, following an unsuccessful software fix by GM, NHTSA issued a consumer alert and Bolt owners were asked to park outside until further notice. A few weeks later, GM announced that they had found the problem – a coincidence of two battery failures – and that dealers would be replacing the modules on all 2017 through 2019 Bolts. In September, the recall was expanded to include 2020-2022 model years, with a full battery pack replacement for 2017-2019 models and module replacement as needed for later years.
Where are we now?
Over half of 2017 to 2021, Bolts have seen a battery swap
By mid-2022, Chevrolet and the National Highway Traffic Safety Administration (NHTSA) reported that well over half of the 2017-2019 model year batteries had been replaced, but less progress had been made on newer models.
Using anonymized data from our community of nearly 1,684 Chevrolet Bolt EVs, we found that 58% of 2017-2021 Bolts have already had a battery change. This includes a large majority of 2017-2019 Bolts. Newer models, believed to be less prone to failure, lag behind.
Here’s a look at the number of Bolts replaced by model year in the Recurrent community.
● 2017: 82.4%
● 2018: 86.0%
● 2019: 88.0%
● 2020: 2.0%
● 2021: 2.6%
Chevrolet has prioritized early model years since the recall began. While this shows that the company has made incredible strides in two short years, this recall is far from over.
Note that while the recall covered 2022 Bolts and Bolt EUVs, there was a suspension period for vulnerable vehicles in mid-year. While Recurrent tracks battery replacements in all vehicles, we don’t know how many 2022 Bolts in our community need one.
Bolt EV range increases by 27 miles after battery replacement
Bolt owners have been through a lot over the past two years, including reduced range and a lot of anxiety. However, once replaced, older models erase years of age-related range degradation. The replacement batteries for the 2017-2019 models also have 6 kWh (or 10%) more capacity than their originals. That means increased range – and a friendly restart of the battery guarantee.
Using data from 1,684 bolts on our platform, we’ve graphed how range has increased as more batteries are swapped out. The chart below shows the estimated full charge range for Bolts before (blue) and after (yellow) the high voltage (HV) battery replacement in 2021 and 2022. You can see that over time and more batteries are being replaced thick yellow line (moving average of the range) pulls away from and above the blue.
The chart above includes some seasonal variations around the winter months when cold weather reduces some range estimates and temperature variations also affect the bolt. The chart below simply compares before (blue) and after (amber) the battery change at some point this fall.
Lessons learned from the Bolt recall
1. The odometer can be a misleading metric on electric cars. I would rather have a high mileage used car with a new battery than a low mileage used car with an old battery.
2. Bolt owners who stayed with Chevy were rewarded with a new, often larger, battery and renewed warranty.
3. GM’s strategy of prioritizing older, more vulnerable battery packs for replacement appears to have worked for +80% of 2017-2019 models that are back on the road with a new battery.
4. Many factors are contributing to the surging Bolt sales this year, but GM’s quick response seems to be helping this leading EV model overcome battery fears. At a high cost, they got it right.