Changed the battery twice and never lost data...its of no concern cause all you have to do is slide the battery contact to the side (.5 sec), remove battery (1 sec), install new battery (2 sec), replace contact (.5 sec). Still got 4 seconds to spare and im not kidding. Also I decided to purposely loose all of my data, removed battery, waited a couple of minutes, replaced battery and only had to redo the presets. Dive data was all retained.
