-
Here is a 28.8A charge from 7% SOC to 100% SOC.
(The input to the OBC averaged 28.7A, 216.4V over 5 hours. Both stay fairly constant throughout.)
(The output from the OBC varies as the battery voltage increases. Voltage goes up, current goes down.)
(The ratio of input power / output power = efficiency was about 89%)
The initial voltage at 7% SOC is 327.4V
The final resting voltage at 100% SOC is 397.8V (each cell at 4.14V)
Cell voltage deviation was zero at all times except for the very lowest SOC when it reached 0.04V
Looking at the values for Cumulative Energy Charged (CEC) - 27.6kWh were added to the battery.
This gives 27.6/0.93 = 29.7kWh usable capacity.
Looking at the values for Cumulative Current Charged (CCC) - 76.4Ah were added to the battery.
This gives 76.4/0.93 = 82.15Ah. (does this represent the usable capacity?)
This is slightly higher than the nominal capacity of 80Ah
---------------------------------------------------------
Looking at the laboratory analysis of a 2015 Soul EV battery pack, I have a couple of doubts about my analysis above.
See
AVT: Battery Pack Laboratory Testing Results
1/ Once the battery gets below about 320V the drop in voltage is no longer linear.
I am assuming above that the lowest 7% of the battery will continue to drain linearly as before. It seems the BMS assumes this too. It may not be true. Perhaps a battery calibration should be done first before a range test.
2/ The measured capacity depends on the C rate. In this graph it is C/3. It may not be the same under other conditions.
In my test charging to 93% SOC took 5 hours, so the C rate is between C/5 and C/6.
This chart shows how the measured capacity of the 40Ah E400 cell varies with different constant current discharge.
From
FY2014_APR_Energy_Storage_R&D (for SK Innovation E400 see printed pages 47-49, on screen pages 95-97)
3/ The measured capacity depends on the temperature rate. For lab testing it is 23C +/- 2C. It may not be the same under other temperatures.
In my recent test the battery temperature ranged about 18C +/- 2C. I think I would get a higher capacity with hotter ambient temperatures.
-