The battery dies steadily in 8-11 months. With a guarantee, everything was perfectly thought out - it is six months. Just after that, the battery will begin to degrade, that is, it will be discharged faster than you vacuum the studio. If you are ready to pay half the price of a vacuum cleaner once a year for a new battery, then this device is for you. It cannot be repaired, the problem is not in the banks, but in the controller.