boatbum11 wrote:I see the same 3.4 volt max on the cells in my 2014 Spark. I know the literature I have seen says 96 cells, but I think the A123 units must have more in parallel to get the 19kwh capacity of the battery, otherwise the cell voltage would be higher. I knew something was up when I divided the battery voltage by the number of cells, it should have read 3.8 volts rather than 3.4 with a full charge and only 96 cells.
Curious-er and curious-er....
I finally found Chevrolet's specifications for the 2014 Spark EV - actually, I found the specs for 2014, 2015 and 2016.
Here is some useful information.
The A123 HV battery used in the 2014 Spark EV is built using 336 cells (3P112S configuration). The battery is rated at 21 kWh. 400 volts divided by 112 cells equals 3.57 volts per cell. 21 kWh / (3.57 V per cell X 336 cells) = 17.50 amp-hrs per cell.
My test results for my 2014 Spark EV with 14k miles on the ODO were: 17.2 kWh battery capacity, 3.41 volts avg per cell which calculates to 15.01 amp-hrs per cell. The SoC of the battery at the time of the test was 99.6% and the GOM read 98 miles after the full charge.
The LG HV battery used in the 2015 and 2016 Spark EVs is built using 192 cells (2P96S configuration). The battery is rated at 19 kWh. 400 volts divided by 96 cells equals 4.17 volts per cell. 19 kWh / (4.17 V per cell X 192 cells) = 23.7 amp-hrs per cell.
My test results for my 2016 Spark EV with 10k miles on the ODO were: 16.6 kWh battery capacity, 4.13 volts avg per cell which calculates to 20.9 amp-hrs per cell. The SoC of the battery at the time of the test was 100% and the GOM read 110 miles after the full charge.
A friend of mine has both a 2015 Spark EV and a 2016 Spark EV and I will be testing these two cars too. He thinks there is a problem with his 2015 which I find interesting as my leased 2015 Spark EV, which I just turned in, looked like it suddenly lost about 1 to 1.5 kWh in battery capacity. Unfortunately, I will not be able to test it to verify the problem.
One thing is certain - I now have a baseline against which to compare future tests to see how fast the HV battery degrades.