My Neato XV-21 works twice a week cleaning a rather small house of about 80 square meters. The replacement battery will definitely wear out faster than the original battery that came with the device. After three years of use, the batteries deteriorated significantly and the device failed to complete a cleaning cycle without returning home to charge for about a year. Now he has to go home to charge at least twice in the cleaning cycle. I have strictly followed the reset procedure when installing replacement batteries, and did so once in the meantime when the batteries first showed signs of reduced run time. .Disappointment and definite weakness in an otherwise great product (Nato XV-21 vacuum cleaner)