It is important that PIEPS users do not use Lithium or rechargeable batteries in the DSP models, Freeride, the Backup transmitter or the TX 600 transmitter.
Even though Lithium batteries are designed for electrical equipment and resist cold much better than alkaline batteries, lithium and rechargeable batteries have a relatively unpredictable discharge curve. One minute your beacon could say 99% and the next minute it could say 1%.
The capacity of an alkaline battery degrades much more predictably, and the circuitry in the avalanche beacon can detect, and display this effectively.
Unless otherwise stated by the manufacturer, all avalanche beacons should use alkaline batteries.