The batterie is lithium and not nickel-metal as an original vacuum, which makes batteries error 0002 those batteries are not 100% compatible, and therefore it needs to update. take in mind that you need to connect the vacuum to a pc and update the firmware version by manual. If you don't want to jump in this advanced, don't buy these batteries!
Never received. The seller provided quickly a tracking number which never worked. 1 month later, when a dispute is opened, the seller took 2 days to answer a message, first: He forgot to send the package. Later, when I told him to send it, took another 2 days to respond that the item was out of stock. Lost time for nothing.