Question for those with OBD2 dongles and Torque Pro/SoulSpy

Your pack is only as strong as the weakest cell, single cell degradation will pull 100% voltage down to that weak cell level, as early gen1 Leaf owners will tell you. A well balanced pack will remain higher longer, giving better range, but ultimately, all EV’s will decline, due to calendar aging primarily, but can be premature if usage isn’t optimal..

 

This was asked on SpeakEV a few weeks back. It seems most report around 407-409 V.
An interesting calculation would be to divide that by 98 and compare that per-cell group voltage with the list of individual cell group voltages.
Perhaps that average will drop over age from 4.17 to 4.06 but I’d want to see more than that one datapoint before assuming anything.

 

I think that the final resting voltage at 100% SOC may be a very inconsistent way to judge battery degradation. All batteries should have similar "full" voltages compared to their own baseline, i.e. Mark's 100% SOC pack voltage was probably always around 400V. What seems more significant is how fast the "full" voltage reading drops. When a battery is new the voltage drop curve is slow, relatively linear and gradual. In a battery that has degraded with increased internal resistance it may very well show a full cell voltage at 4.17V like a new battery but it will rapidly drop to 3.9V( I picked this value arbitrarily) under load and then do its slow linear drop. Ultimately voltage measurements give us a clue to degradation but the they are no substitute to measuring internal resistance. I just don't know of a easy non destructive way to do that with our EVs.