Your eBike battery can be charged after every ride, or when it is flat. There is no need to fully discharge the battery before recharging it and we recommend topping up your battery with a short charge after each use, as lithium batteries actually prefer shallow discharges.
Whatever you do, do not leave a battery with no charge for any length of time. After a matter of weeks, if left in a totally drained state, the battery will instigate a shut-down process that cannot be reversed. Please keep you battery charged if not being used for any length of time! (Or simply enjoy riding your eBike on a regular basis.)