al 50% yo creo que está bien
Del manual de yamaha:
Long storage period (1 month or longer) and using it again after a long storage period
When storing the bicycle for a long period (1 month or longer), remove the battery pack and store it using the following procedure.
• Decrease the residual battery capacity to where one or two lamps are lit, and store it indoors in a cool (10 to 20 °C), dry place.
• Check the residual battery capacity once a month, and if only one lamp is flashing, charge the battery pack for about 10 minutes. Do not let the residual battery capacity become too low.
• If you leave the battery pack at “full charge” or “empty”, it will deteriorate quicker.
• Due to self-discharge, the battery slowly loses its charge during storage.
• The battery’s capacity decreases over time but proper storage will maximize its service life.
• When using it again after a long storage period, be sure to charge the battery pack before using it. Also, if you are using it again after storing it for 6 months or longer, have your bicycle inspected and maintained at a dealer.