Storing Batteries - Psion Teklogix 7535 G2 User Manual

Chapter 3: Getting To Know Your 7535 G2
Monitoring The Battery And Maximizing Run Time
• The hand-held battery is a 'smart battery' with built-in intelligence. The taskbar battery
icon is a linear gauge used to estimate the remaining run time of the battery. It is impor-
tant to note that the battery capacity icon displays quarter percentages of nominal
capacity (the capacity of a new battery). An aged battery, even when fully charged,
shows somewhat less capacity than nominal.
Double-tapping on the battery icon displays a dialog box that provides detailed information
about the battery status and performance. If the remaining capacity indication seems inaccu-
rate, the battery may need recalibration. Recalibration requires that the battery be fully
charged, discharged and then charged again before use. If the battery is fully discharged and
charged on a regular basis, recalibration should not be necessary.
• When the hand-held is switched off, it goes into a low-power, suspend state but contin-
ues to draw a small amount of power from the battery. This should not be an issue unless
the unit is left in suspend state for more than a week—in this case, the battery should be
removed.
• Batteries left unused for durations of more than one or two months should be fully
charged, operated in the hand-held until the battery is empty (i.e. the low battery
warning appears), and then charged again before use. This recalibrates the gas gauge
and allows the internal electronics to determine the actual capacity of the battery. See
"Battery Gas Gauge Calibration" on page 180 for a detailed discussion of battery
calibration.

3.1.4.1 Storing Batteries

Long term battery storage is not recommended. If storage is necessary:
• Always try to use a 'first-in first-out' approach to minimize storage time.
• Lithium-ion batteries age much faster at elevated temperatures. Store batteries at tem-
peratures between 0° C and 20°C.
• Always charge batteries to 40 to 60% before storing them. Batteries can be damaged by
an over-discharge phenomenon that occurs when an empty battery is stored for a long
period of time such that the cell voltage drops below a lower limit.
• To minimize storage degradation, recharge stored batteries to 40 to 60% every 4 or 6
months to prevent over-discharge damage.
• A 'never used' Li-Ion battery that has been stored for 3 years may have limited or no
useful life remaining once put into service. Think of batteries as perishable goods.
42 Psion Teklogix 7535 G2 Hand-Held Computer User Manual