On Wed, May 02, 2018 at 08:14:24AM +0800, Mark Webb-Johnson wrote:
This seems to be a hot topic amongst Nissan Leaf owners. Am I correct in that the displayed SOC doesn’t show degradation?
Yes, 2nd gen and later models have a numeric 0–100% SOC meter, which does not account for degradation---there was a separate 12-blob "health" gauge for that, though that's gone on the 2018 model. I think a lot of this stems from the fact that the 1st gen didn't have any numeric SOC display; they had only a 12-blob "fuel" gauge. Indeed, it was this lack of precision that sent many of us rummaging on the CAN bus to find better values. As there was no documentation and no standard set by the manufacturer, conventions arose piecemeal as new nuggests were discovered, which gave us GIDs and the SOC meter relative to original battery size (which may not have seemed so arbitrary when there was was only one original battery size).
In general, OVMS has tried to remotely show exactly what was on the car dashboard. We went to some extreme lengths in the original Tesla Roadster code to meet that requirement (for example the km/miles conversions were not accurate in the car implementation, so we tried to mimic the car’s inaccurate algorithm in our approach).
Absolutely no objection to adding vehicle specific metrics. A GID value (for Nissan Leaf) is the obvious example, but also other indications of battery health. We have SOC%, SOH%, and CAC currently as global metrics.
I think these are adequate, although I think it might also be useful to have "battery energy available" in kW·h, for easier range calculations, (although I see that vehicle modules mostly make their own range calculations, some quite elaborate).