Rockwell Automation 1748 DataSite Configured Panel Installation Instructions - Manual (Page 47)

Publication 1748-IN001B-EN-P - May 2009
DataSite Configured Panel Battery 47
Battery Life Expectancy The life expectancy of the battery, also referred to as the number of charge
cycles, is a function of both the discharge rate as well as the depth of discharge.
Just as the temperature affects the capacity of the battery, it also affects the
number of charge cycles available from the battery.
Life expectancy is determined as the number of charge cycles before the
battery can no longer hold an adequate charge. End of life for a battery is
defined as the ability of the battery to hold in capacity, less than 60% of its
original rated capacity when fully charged at 20 °C (68 °F). This means that if a
battery had a rated capacity of 100 AH, but the maximum charge capacity of
the battery is now only 60 AH at 20 °C (68 °F), the battery is at the end of its
life.
Although the battery life is determined by the amount of charge capacity, it is
not dependent on temperature. The determination of a battery at end of life
can only be done by testing the overall capacity of the battery against its rated
capacity from the factory at the rated ambient temperature which is 20 °C
(68 °F).
Temperature Effects
On average every 10 °C (18 °F) increase in temperature above 20 °C (68 °F)
will decrease the battery life by one half. See
Temperature Effects on Battery
Capacity and Expected Life for expected battery life based on ambient
temperature.
Rate of Discharge
As the rate of discharge increases the overall life expectancy of the battery
decreases. High discharge rates should be avoided to ensure proper battery life
expectancy. To eliminate the possibility of high discharge rates, it is
recommended that no external loads be connected to the DataSite configured
panel in excess of 1 W.