EVDRIVER wrote:People thought the pack was 24kwh and would use 80% and go 100 miles, I knew that was not possible nor did I believe any auto maker would cycle batteries 95-100% DOD. This explains the the 24 KWH usable. 80% DOD at about 30 kwh is 24 kwh
Some people didn't.
May 8th: http://www.mynissanleaf.com/viewtopic.php?p=2568#p2568
May 9th: http://www.mynissanleaf.com/viewtopic.php?p=2670#p2670
May 11th: http://www.mynissanleaf.com/viewtopic.php?p=2770#p2770
My guestimate from May is that the cells are about 40Ah each for a 27kWh pack. I think they're actually larger than that - and we have one member that held a cell and seemed to think it was a similar size to a 50Ah cell.
What we know:
The pack has 48 modules of 4 cells (192 cells total)
Nominal cell voltage is 3.6V
AESC's battery page says their EV battery is made from 33Ah cells. We don't know for sure that the Leaf will use 33Ah cells.
Mark Perry reported in DC that the consumer state of charge range was the 'middle' 80% from 10% to 90% charged.
Pack capacity is cell capacity times nominal voltage times number of cells.
An example using an AESC standard 33Ah cell in a Leaf pack:
33Ah * 3.6V * 192 = 22,809.6Wh or 22.8kWh
This is smaller capacity than even the Leaf's reported 24kWh consumer capacity. This suggests the cells must be larger. As already reported, we need a 30kWh pack to get 24kWh of usable energy at 80%.
30,000Wh / 192 / 3.6V = 43.4Ah
The cells need to be at least 43Ah each to give a 24kWh pack when new. But if the cells are 50Ah, we'd start with a pack that could provide up to 34,560Ah when new...and that would give some 'extra capacity' that could be used later in the pack's life. I'd use 50Ah cells if it was important to maintain a minimum drive range at end of pack life...
One last pack indicator - technically 'hearsay' but also from Perry in DC - the suggestion that total pack size is 32kWh: http://www.mynissanleaf.com/viewtopic.php?p=17255#p17255
A 32kWh pack size means we need 46.3Ah cells.
I'm feeling pretty good about 46-50Ah cells for a total pack capacity between 31.7kWh and 34.5kWh