Re:Rechargeable vs. Alkaline Batteries
by sixstringtheory on Monday July 22, 2019 @05:07PM
(#20502338)
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.
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Alkaline batteries start off at 1.5-1.6 volts and the voltage follows the charge reasonably linearly down to about 1.0 volts. So that's correct, alkaline batteries at 1.5V per cell are 'good' full stop. Where a rechargeable at 1.2V might or might not be. Who really knows if it charged all the way[1][2].
[1] Gallant is careful to put his nmh batteries in the the charger each night. Goofus got high and forgot. In the morning Goofus swapped his dead ones for the ones in Gallants charger.
[2] Power went out between 11pm and 6am while everyone was asleep.
I have one of the few avalanche beacons that have separate modes for alkaline and NiMH batteries. (Specifically, the Barryvox Pulse.)
My understanding is that "alkaline mode" measures the voltage to determine charge level, as one would expect. The "NiMH mode" instead uses a timer-based approach to estimate charge level due to the different discharge curve.