As I posted at MNL but with some minor edits:
The final procedure for covering all the recalled vehicles (all '17 and '18 + subset of '19) is up at https://static.nhtsa.gov/odi/rcl/2020/RCSB-20V701-3618.pdf. As usual, there was a lag before appearing at NHTSA. The '17 and '18 final remedy came out on 5/26.
https://www.nhtsa.gov/vehicle/2017/CHEVROLET/BOLT/4%252520DR/FWD#recalls grew from 29 to 34 associated docs sometime a few days back.
https://gm-techlink.com/?p=14834 explains the new DTC and diagnostics.
trevmar said:
I don't see the significance of the 80mV drop. Why not 79 or 81mV?
Or 5mV?
Cells made at the same time from the same raw materials should all have the same OCV IMO
As a Leaf driver who can see voltages including the delta between min and max cells or modules via Leaf Spy, there's always a bit of imbalance, but they're under some load when the car's on in READY mode. Max delta is usually no more than 20ish or 30ish mV, IIRC and sometimes in the single digits.
https://www.mynissanleaf.com/viewtopic.php?p=457964#p457964 was an example of a Leaf w/a bad module showing 164 mV delta between min and max at pretty low SoC. In Leaf-land, Nissan has a CVLI test: https://www.mynissanleaf.com/viewtopic.php?t=16070.
I've never run my Leaf to super low but the author of Leaf Spy told me about the delta being hundreds of mV when his '11 is close to dead: https://www.mynissanleaf.com/viewtopic.php?p=516652#p516652.
I think it's a good guess that GM believes these diagnostics and thresholds + new/updated DTCs are sufficient to identify cells w/latent defects (alluded to near the end of page 1 of https://static.nhtsa.gov/odi/rcl/2020/RCLRPT-20V701-7407.PDF).