On a volumetric energy density basis compared to 18650's in the 100D
I've checked my math numerous times and I can't find an error. If the numbers are right it'd really not earth shaking news since the whole idea of the 2170's is to lower costs. If correct it possibly implies that Tesla Panasonic just repackaged the existing 18650 cell into a new form factor and there is no "secret sauce" in the new 2170's.
The key to the calcs is the usable energy in the EPA report.
http://www.teslarati.com/wp-content/uploads/2017/09/Tesla-Model-3-EPA-CSI-HTSLV00.0L13.pdf
usable energy for 2170's in Model 3 is 78.3 kwh in the new model 3 long range pack
Tesla Model 3 actually has 334 miles of range according to EPA data
It actually is there more than once in the report on pages 6 and 7 at the bottom of the page it says:
"Manufacturer Test Comments Internal Test results for MY2017 Model 3 Long Range. Range determined by using SAE J1634 Multi-cycle test procedure. END-SOC 78270 wh."
also it says:
"Integrated Amp-hours 222.81
Average System Voltage 351"
multiplying those 2 numbers = 78273 watt hours
Therefore usable energy= 78.3 kwh
number of cells in big model 3 battery=4416
Tesla Model 3: Exclusive first look at Tesla’s new battery pack architecture
therefor usable energy per cell is 78.3/4416=.0177 kwh per cell
model S 100D pack has 8256 cells and 98.4 kwh usable energy
Teardown of new 100 kWh Tesla battery pack reveals new cooling system and 102 kWh capacity
therefore usable energy in one 18650 cell=.01192 kwh/cell
Therefore increase in usable energy in one 2170 cell is 48% greater than the 18650 (.01192/.0177)
Volume in 2170 cell is 47% greater than the volume in the 18650 (simple volume calc for 18X65 vs 21X70 cells)
so energy went up 48%
volume went up 47%
basically the same within 1%
Do these numbers make sense? Can you guys find any holes in this analysis or math errors??
Thanks,
George