Co-author of CanZE. Q210 nov 2013
SOH is a complicated discussion, that is always muddled with tiring conspiracy theories (QED ^^). While it would be better to start from scratch again, allow me to just put in some bullet points.
- CanZE just reads a field "SOH" from the Battery computer. That's it, no added intelligence from the app.
- The battery computer (LBC), AFAIK, is made by LG-Chem. Car makers are systems integrators, and it's not different for Renault or EVs.
- SOH is usually defined as the Ah capacity, divided by the nominal Ah capacity, which is why new cars usually come with 103 or more % SOH. SOH is not a kWh ratio. The difference between Ah and Kwh capacity is subtle but not insignificant.
- Since the car basically never does a full battry cycle, the LBC is unable to determine the actual SOH, so it does a fair estimation based on the Ah / voltage curve (it can measure the current going in and out, and the voltage per cell pair, see the Voltage Heatmap).
- If the LBC is fully reset, it will assume the SOH is 98% and will trickle down to the "real" value in the next few weeks. Or months. An endless feeding trough for the c-theories.
- My 72000 mi Q210 from late 2013 is on 80%.