SageBrush said:
WetEV said:
Gold standard test would be to get battery to known temperature and near VLBW, then measure power needed to recharge. Compare with new car measurement at same temperature. Or a careful range test comparing a new car with an older one. Again, I suggest stopping at VLBW for both.
That would not tell you anything
We have groups using different methods. We are trying discharge from 100% at constant current of C/3 with a Dynapack load (hub dynamometer) and measuring time down to at least VLBW or lower which when multiplied by nominal voltage gives kWh (to that SoC). Current is measured via a modified service disconnect plug to bring out a wire loop for minimal modification to the car.
Another approach is the charge method, starting from turtle, up to 100%, measuring kWh to car with EVSE and/or external check meter, and applying a correction for charging efficiency of nominally 88% at 230V and 16A. The charge method is easier to do and can even form a statement of health (by that method, noting temperature) for selling a used car. We know it isn't precise but could be adequate guide. This is important for the import industry here where up until now Leaf Spy has been used and accuracy is being questioned where there are 30kWh cars with 1 and 2 bars down being sold and some feel not much range has been lost.
A third approach has been run-out driving and good distances are claimed on reportedly degraded packs but it seems to me it could be subject to significant variability and some of these tests are at low speed. Hopefully over coming weeks we will get a better idea of the answers from each method and how well they relate to the Leaf Spy reported SoH.