The 1st generation Volt started with using 65% of the battery with an upper state of charge of around 85-87% and a lower state at around 20-22%. The 2nd generation Volt uses about 76% of its capacity (14.0 kWh out of 18.4). Presumably better experience, battery design improvements, and the benefits of larger capacity (less likely to be fully discharged of usable capacity each charge cycle) lead to the increased state of charge usage. GM has claimed that battery aging studies project that the 2nd generation packs should last at least as long as the 1st generation packs and perhaps a bit longer.
If you believe that the Bolt EV's nominal capacity is not much more than the published 60 kWh then it appears to allow nearly all of the battery to be used. It may well charge as high as 97% and allow discharge down to near 2-3% at reduced speeds before finally rolling to a stop. Those numbers are just guesses because GM has not released actual numbers and some people suspect that the battery may be noticeably larger than its claimed size of 60 kWh thus allowing a bit more of a buffer zone at the top and bottom.
If you believe that the Bolt EV's nominal capacity is not much more than the published 60 kWh then it appears to allow nearly all of the battery to be used. It may well charge as high as 97% and allow discharge down to near 2-3% at reduced speeds before finally rolling to a stop. Those numbers are just guesses because GM has not released actual numbers and some people suspect that the battery may be noticeably larger than its claimed size of 60 kWh thus allowing a bit more of a buffer zone at the top and bottom.
