Another downside and word of caution: I left my $1200 Rad City bike in the garage over the winter and it got unplugged somehow. By spring it was no longer able to charge, and replacing just the battery cost another $600.
FWIW, I would encourage anyone who isn't certain enough about it to buy a $3,000 bike to start with a cheaper Chinese model to decide if it is for them. There are things I don't love about this bike, but it definitely has me sold on electric assist bikes given the hills I have around me and my knees, and when it comes time to replace it, I expect I will get a nicer model.
Quite probably there was something wrong with that previous pack already that caused a self discharge rate so high that the pack had gone completely empty.
The best way to store them for long term is to charge to either 3.7 or 3.9 V / cell (depending on whether you want to check them in 3 or in 5 months).