The Oyster Cellular tracking unit uses 3 x “AA” cell batteries. The circuitry is designed to handle battery cell voltages from 1.5V to 1.8V, suitable for use with Li/FeS2 batteries such as the Energizer Ultimate Lithium (L91). It can also operate briefly on regular Alkaline batteries.
Predicting the battery life is quite difficult, due to the wide range of operating conditions.
The battery life is affected by:
The type and quality of batteries used
The type of modem (2G, 3G, LTE), and the average signal strength
The average GPS signal strength available when installed
The average temperature of operation
The operating mode (periodic, GPS based tracking, accelerometer based tracking)
The particular configuration of that mode
The level of asset activity (trip quantity and length, loading / unloading jostling)
To help inform the battery life prediction and evaluation process, many discharge tests have been performed, and approximate battery cost constants extracted.