The short answer is there hasn’t been any degradation of the traction battery of our 2027 Bolt after nearly 12,000 miles. State-of-Health is still showing 100% and Car Scanner ELM OBD2 app is still showing 70.2 kWh of battery capacity. The app’s measure of capacity has held remarkably steady, bouncing around only between 69.6 and 70.2 kWh after each charge.
In contrast, battery capacity of our 2017 Bolt, 2020 Bolt, and the 2020’s replacement battery varied appreciably from one charge session to another.
While my records are not complete, the data I have shows the capacity of the earlier models fell from ~1 kWh to as much as ~6 kWh for the same mileage. These values should be taken with a grain of salt. With the first generation Bolt, I only later began using Torque Pro and OBD-II PIDS (Parameter IDs) deciphered by Sean Graham. (See Peeking Inside the Bolt’s Brain Reveals Valuable Secrets.) During the early years, I used the ratio of the kWh’s consumed to the SOC before the next charge session. The two give different values and vary considerably from one charge session to another.
With the current Bolt I am using Car Scanner ELM OBD2. I don’t know what PIDs it uses or how it determines which parameter it records. Furthermore, I don’t know if the 100% State-of-Health is the state of health at 70 kWh or the state of health at GM’s advertised capacity of 65 kWh. Until I learn otherwise, I’ll assume the app is recording what it says it’s recording.
In summary, the earlier Bolts showed measurable degradation after 12,000 miles, but the 2027 does not.
