Zoomit said:
I'm not so sure. We don't have enough data yet to be conclusive, but it appears the pack is 60kWh and all that is available to the driver if desired. It also appears there will be charging feature that lets the owner set the charge to stop at 90%.
The entire pack is
never available, there is always a buffer on both the bottom and top. Some manufacturers release that info (BMW, for example), others do not and it is not clear on what the pack size refers to - actual or usable.
There is a term for completely discharging a Li-ion battery - "Bricking". Once you do it, your battery is about as useful as a brick for powering a car (or anything for that matter). The BMS will shut the car down completely before you can fully discharge your battery pack.
From the published reports on the Monterey to Santa Barbara, journalists reported figures like 58.7 kWh used (with range remaining). This is a pretty good indication that the usable energy is 60 kWh hours (or even a little more). The physical pack capacity is unknown.
It appears that Nissan makes about 97% of the LEAF pack available - and that may be part of the degradation issues they have (along with lack of thermal management).
Of those that publish actual/usable - BMW allows 87%, Kia 88%, Chevy (on the Volt) 75%.
I think it very likely that Chevy will have at least a 10% buffer, so actual pack capacity is likely 66+ kWh.
There were early reports that LG was supplying 55 Ah, 3.75 V 3P96s cells in the Bolt pack (which has 288 cells). That would yield 59.4 kWh. I believe they have gone to a 65 Ah cell (from info on the new 40 kWh Zoe). That would yield a 70.2 kWh pack and an 85% utilization.
There also some indications LG has or had a 63.35 Ah version that would yield a 68 kWh pack and 88%.
The diagram in the original post is misleading - there are 96 cell groups with 3 cells per group. While it appears that there are 5 "packs", the rear two stacked "packs" (at least the top one) are narrower.