I wonder why it's 80% and not 85% of the battery? of course I'm not an engineer so I don't have that answer. I anticipate charging it about once a week once it's charged to 80% well, after the first few months of fun driving that is. Or should I top it off every night?
It is a round number of the percentage where the charging slows while fast charging. The migration of the battery chemicals slows as you get a smaller percentage in the uncharged form.
For home charging I don't notice the rate being slower to go to 100% since it is anyway overnight. Also, when I charge overnight I look at the estimated completion time and lower the charging current until it just reaches 80 or 100% by morning. That should put less heat into the battery.
There is a "preconditioning" setting, but I think that one waits to start charging until just in time, rather than lowering the current.
When I want to drive 2-3 hours into the mountains I slow charge to 100% because there are few chargers there, and you have to "lend" range to go up the mountains. So you use more range than the distance traveled.
If you drive in B mode you get back the range you used to climb. I find that I can gain 40 miles of range going down the mountain. So I like to keep the buffer for going up.
To drive shorter trips I just bring it to 80%. I see no reason to charge every day. Your remaining charge and range is always on the instrument screen, so there is no suspense.
Plus, once you know where the public chargers are in the region you can plan on hitting those. I don't use the fast chargers past 80%, since they slow down after that and you pay by the minute.
BMW gives us 30 minutes free charging at EA. That is enough to go from 30% to 80%.
You will see your car soon. Enjoy it.