I think about EV battery health and range every day. This means that major battery recalls, like the one GM announced 2 years ago this week for the Chevrolet Bolt, are of particular interest to me and my fellow battery nerds. Battery replacements, in general, raise an important question for electric cars: is the odometer a good indicator of the vehicle’s value? A Bolt with 50,000 miles and a replacement battery is as good, if not better, than new.
My team of battery scientists have been closely monitoring and reporting on the Bolt recall since it was first announced in November 2020. Every day over 1,600 Bolt owners monitor their electric vehicles with Recurrent and this data gives us insight into the performance of their batteries before and after replacement.
The Origins of the Bolt Battery Recall
In November 2020, after a handful of seemingly unrelated fires, Chevrolet issued the first Bolt recall for the 2017 through 2019 Bolt model years. The company asked owners to limit load capacity to around 90 percent and bring cars to a dealership for diagnosis and possible replacement of the battery module. Based on driver data, we found that 16% of owners stopped charging 100% in response to safety guidelines.
In July 2021, after an unsuccessful software fix from GM, NHTSA issued a consumer alert and Bolt owners were asked to park outdoors until further notice. A few weeks later, GM announced that they had found the problem – a coincidence of two battery faults – and that dealers would replace modules on all bolts from 2017 through 2019. In September, the recall was expanded to years 2020 to 2022 models, with full battery pack replacement for 2017 to 2019 models and module replacement as needed for later years.
Where are we now?
More than half of Bolts from 2017 to 2021 had a battery replacement
In mid-2022, Chevrolet and the National Highway Traffic Safety Administration (NHTSA) reported that well over half of 2017 through 2019 model year batteries had been replaced, but progressed less 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 replacement. This includes a large majority of bolts from 2017 to 2019. Newer models, which are assumed to be less at risk of malfunctioning, lag behind.
Here is an overview of the number of bolts per model year that have been replaced in the recurring 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 progress in two short years, this reminder is far from over.
Note that while the recall covered the 2022 VUE Bolts and Bolt, there was a mid-year cutoff for at-risk vehicles. While Recurrent tracks battery replacements in all vehicles, we don’t know how many 2022 bolts in our community need them.
Bolt EV range increases to 27 miles after battery replacement
Bolt owners have had to go through a lot over the past two years, including reduced range and a lot of anxiety. However, after replacement, older models erase years of battery life degradation due to age. Replacement packs for 2017 to 2019 models are also 6 kWh (or 10%) higher in capacity than their originals. That translates to increased range – and a courtesy reboot on their battery warranty.
Using data from 1,684 bolts on our rig, we have graphically represented how range has increased as more batteries are replaced. The table below shows the estimated range at full charge for the Bolts before (blue) and after (yellow) high voltage (HV) battery replacement in 2021 and 2022. You can see that over time and as more batteries are replaced, the thick yellow line (moving average of the range) moves away from the blue and goes beyond it.
The graph above includes some seasonal fluctuations 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 (yellow) battery replacement at some point this fall.
Lessons from the Bolt Rappel
1. The odometer can be a misleading measurement in electric cars. I would rather have a higher mileage used car with a new battery than a lower mileage used car with an old battery.
2. Bolt owners who remained loyal to Chevy were rewarded with a new, often larger battery and a renewed warranty.
3. GM’s strategy of prioritizing older, more vulnerable batteries for replacement appears to have worked with +80% of 2017-2019 models back on the road with a new battery.
4. Many factors are contributing to the Bolt’s sales surge this year, but GM’s quick response appears to be helping this leading electric vehicle model overcome battery fears. At a very high price, they handled it well.
#Learned #Years #Chevy #Bolt #Recalls