HMI SoC is inaccurate on 45/55kwh ID.3

[tolnaiz]

This calculation seems to be inaccurate on the pure models.

evDash/src/CarVWID3.cpp

Line 315 in ad4c152

liveData->params.socPerc = liveData->params.socPercBms * 51 / 46 - 6.4; // SOC HMI

Also, batModuleTempCount is 16 and cellCount is 96 on the pure model.
Basically vw just removed one battery module from the 58/62kwh version.

[spot2000]

In what span is it inaccurate? Please provide examples, I updated the formula today with a better formula, at least for 58 and 77 kWh MEB cars.

[tolnaiz]

The biggest differences are above 50%.

This is what I see in the car with OBD:
Car reports 100%, battery BMS SoC is at 86,4% with EvDash's new formula it's 89,38%
At 76%, BMS is at 69,2% when evDash would be: 70,3
At 51%, BMS is at 50%, evDash: 49,11%
At 18%, BMS is at 22,8%, evDash: 19,02%
The lowest SoC I was able to record with OBD is 11% when the BMS SoC was at 16%, evDash: 11,5

Unfortunately these numbers doesn't even fit on a line:
https://www.wolframalpha.com/input?i=plot+points%5B%2816%2C+11%29%2C+%2822.8%2C+18%29%2C+%2850%2C+51%29%2C+%2869.2%2C+76%29%2C+%2886.4%2C+100%29%5D

I measured these numbers at very different time, so maybe temperature, SoH or other factors could affect the calculation.

The best formula I was able to figure out is this: y = x * 0,505-9,0947
This fits better, but still not perfect.