Ingineer wrote:Nissan calls it stored watt-hours... Either way, I can assure you what you are calling SOC, Nissan is calling stored watt-hours.
TickTock wrote:Since gids are a unit of energy and the battery has losses, gids out will always be less than gids in. Total round trip efficiency is 85% and half of this comes close to 75/80 so the numbers start to make sense if you account for losses. The 281 everyone (else) sees after a 100% charge is probably "gids in." Not to be confused with "gids out." Add this on top of the integrating error, hall effect sensor drift, etc, and we can see why the ECU needs to adjust the value time to time.
I agree with what Luke and Phil said above. There is a difference between stored and expended energy. I'm not aware of any empirical data that would support more than 75 Wh per gid when looking at the expended energy. Luke's plot earlier in the thread
was recorded when charging, not when driving. His findings support 80 Wh per stored gid.
I have another datapoint for that. The general agreement seems to be that the difference between a 80% and a full charge is 4 Kwh. Measured from the wall and adjusted for charging inefficiency. I used Gary's meter for much of last month, and a 80% charge corresponded to 231 gids. A full charge was either 280 or 281 gids. A delta of 50 gids, 4 kWh, or 80 Wh per gid stored.
I tried to validate this number in the spreadsheet
I compiled for the reverse SOC meter project
, and the best I got was 3.67 kWh or 73.4 Wh per gid expended. I chalked it up to low temperature and losses, although I still don't understand where exactly they come from. Drivetrain inefficiency should be baked into the MPK number, and the coulombic efficiency of the battery is likely greater than 99%. What is the accuracy of the odometer? What else could we be missing?