Wow that is strange, if it still counts the operating time even without the battery, it can be still be operated by some sort of CMOS battery that counts time even when a machine is off, like alarm clocks and computers, they still keep a time to count but that’s my guess and removing a CMOS battery (Not regular battery) may be the only way to fully stop the time. Usually it barely uses any energy when its counting time but I can see why this may be of concern since all electronics has a certain lifespan it can run before it starts going bad and forces you to buy a new one. Hope you can figure this out soon and hope this helps.