The battery lasts around 14 days with normal use (cleaning twice a day), and up to 22 to 33 days when tested, depending on the cleaning mode and intensity. This corresponds to around 28 to 66 brushing sessions without recharging. This means you don't necessarily have to take the charging glass or case with you on a week-long trip, as the battery will last this long without any problems. The included charging case also makes it easy to recharge via USB when travelling if you do need to charge.