Slightly related, and maybe you could provide more knowledge here: common knowledge for safety critical devices, such as avalanche beacons, is to only use disposable alkaline batteries. The reasoning I've heard is that due to the flat power curve of non-alkaline batteries, if you put a nearly-dead one in the beacon and check the battery level, it will read as fuller than it really is, and you run the risk of having it die on you during a normal usage period (maybe 12 hours). With an alkaline battery, when it's close to done, it will more accurately register as such on the device.