In the range of current chargers, only the CR246 (and CR65) offers float charging for storage operation of a rechargeable battery.
Stromer writes:
The battery management system (BMS) also consumes a small amount of power, which slowly discharges the battery. If you do not use your bike for a longer period of time, we recommend connecting the bike to the CR246 charger, which offers the option of float charging. Float charging automatically keeps the battery in the optimum charging range. This means that the charging process is stopped after a full charge until the charge level of the battery has fallen back to approx. 60 % after around 3 weeks. The charge level is then kept constant at 65-80 % until the charger is disconnected from the battery.