A 500 watt-hour battery will fully charge in 4.5 hours using a standard charger. To charge your Bosch bike, ensure the battery and charger are in a dry, well ventilated area. Plug the charger in to the charging port on the bike. To charge off the bike, plug in to the port on the bottom of the battery. Be sure to plug directly into a standard wall outlet, do not use timers, surge protectors, or power strips. Remember to charge in room temperature and avoid storing and charging your battery in the cold.