great product but leave the battery cap off between uses [SEP] sonicare are great products as my dentist has noticedthe only problem with this great replaceable battery version is that the batteries did not last for more than a week or two until i discovered that removing the battery cap between uses made the batteries last as longi can only guess that there is a small constant current drain on the batteries removing the cap disconnects them and stops that constant hour a day drain then they last fine i use nimh rechargeables