Our 2020 Chevy Bolt’s traction battery was replaced under warranty on 6 May 2022 by our local Chevy dealer.
I’ve written previously about the failure of our 2020 battery. See Our Bolt is back with a New Pack—In Limbo No More.
The nominal advertised capacity of the 2020-2022 traction battery is 66 kWh. Previously, Chevy marketed the Bolt with a 60 kWh battery. We leased a 2017 Bolt for three years.
We’ve never seen 66 kWh in any of our Bolt batteries using standard measurement methods. However, we have seen greater than 60 kWh in all three batteries (2017, 2020, and 2022 replacement battery).
Measuring Battery Capacity
There are two methods consumers can use to measure the capacity in the Bolt’s traction battery: Torque Pro & OBD; and kWh consumed & State-of-Charge.
One method uses Torque Pro on an Android phone to record several measurements from the Bolt’s brain through a dongle plugged into the On-Board Diagnostic (OBD) port. Torque Pro takes the signals from the Bolt and translates them into something meaningful using PIDs (Parameter IDs) developed by Bolt driving techies like Sean Graham. The results assume that Graham and his collaborators have interpreted the PIDs correctly.
The second method uses the ratio of the State-of-Charge (SOC) remaining in the battery after driving some distance and the kWh consumed. Because the Bolt doesn’t report SOC directly, finding the SOC requires using Torque Pro again and the specific PID for SOC. The Bolt reports kWh consumed directly.
For example, if on our last full charge, we consumed 31.2 kWh and arrived home with 45.9% SOC, there was 57.7 kWh available.
31.2 kWh/(1-0.459) = 57.7 kWh
Of course you don’t need to charge to full to use this technique. You simply adjust the starting charge accordingly.
The capacity resulting from both techniques varies from one charge to the next so it’s necessary to look at the trend and not any one measurement.
Your Mileage May Vary
In our 2017 Bolt, we started with ~61 kWh using the OBD method, and from 61-64 kWh using the percent consumed method. See Slight Chevy Bolt Traction Battery Degradation after Nearly 30,000 Miles.
In our 2020 Bolt, a linear regression analysis of the data pointed to 64.4 kWh as the initial capacity.
The capacity or our new battery has declined from an initial 62 kWh to 60 kWh during the first month since the battery was replaced as measured using Sean Graham’s PIDs. During this period we’ve charged eight times to 100% and driven 1,000 miles.
The capacity of the new battery using the percentage SOC has ranged from 61 kWh to 64 kWh.
While the capacity has declined steadily–though slightly—according to the PIDs, the capacity using the percentage SOC has held relatively stable at 63 kWh.
Because it is the kWh consumed relative to the SOC that determines how far we go in an EV, it appears that the percentage SOC method for determining battery capacity is the more meaningful of the two techniques, though individual measurements are more variable.
GOM Still Guessing
The GOM (Guess-O-Meter) or range indicator is still adjusting to the new battery. The mid-range estimate is averaging well over 300 miles.
While every Bolt driver likes to see range estimates hovering around 300 miles, we’ve driven Bolts long enough to know that with an average efficiency of just over 4 mi/kWh and capacity of 60 kWh we can reasonably expect ~250 miles of usable range.
We’re satisfied with the new battery, both in capacity and range, and with the promptness with which GM finally replaced the defective battery.
