The batteries for the Disetronic pump are the same as the batteries used in the MiniMed pumps (Eveready 357 or equivalent), except the Disetronic batteries are specially mounted in waterproof casings. There is a small "O-Ring" around the edge of the Disetronic battery case to keep water from entering the battery chamber in the pump.
These batteries can be changed or "refreshed" by carefully opening the case and replacing the old batteries with new ones. If you are ever stuck in a situation where you do not have access to the "official" Disetronic supplied batteries, this will save you.