This document describes the expected service life of the backup battery currently installed in the WORKABOUT PRO G2 (WAP2, 7527) hand held computer.
The back-up battery pack of the WORKABOUT PRO G2 (PTX Service P/N 1050944 or Workabout Pro G2 Accessory model number WA3019) is composed of a single Li-Ion cell with a rated capacity of 140 mAh. Since there are no calendar life specifications from cell manufacturers beyond 1 year, we can only estimate the usable life of the battery based on our experience with other cells of this type.
As very little charge capacity is required in its application, the number of cycle counts that the battery would see during typical use should not be an issue . So an estimate of the shelf or calendar life is what we are seeking here.
From typical shelf life or low usage rate experience with other similar batteries, a shelf life of approximate 3 years can be expected when properly stored. As a cell ages it will suffer charge capacity degradation, increased internal impedance amongst other factors that will degrade performance to the point where it may no longer be able to provide sufficient power to drive the circuit.
Since our charging algorithm for 7527 back-up cell keeps the battery optimized for low usage rate conditions, we would expect that this 3 year number would be the typical life a user should expect from the pack under typical conditions.
Factors that would negatively affect this typical value are as follows: