Very easy. It is quick and simple to swap the batteries in the watch band for the batteries in the charger. The batteries are about 1 inch square, so they are designed for people with limited dexterity. While we have many wearers in their 60s and 70s (and even younger), our oldest wearer is currently 103, and she has been changing her batteries regularly for years with no issues. See how easy it is to swap batteries.