I haven't seen this discussed before, so I thought that I would mention it.
When I set both the 120v and 240v charging to their lowest setting, my i3 automatically stops charging at 85% or 87% capacity. Like others, I've been somewhat disappointed by the inability to avoid charging to a full 100%. However, I seem to have accidentally stumbled onto a hidden feature, either that, or my i3 is not working properly
Since I live in Phoenix, and my garage is regularly over 100 degrees this time of year, I like being able to leave the i3 plugged in all night to keep the battery cooling system active. This seemingly hidden feature allows me to check both boxes, keeping the battery cool, and not charging to a full 100%.