User's Manual

Operation: C1SD, C1ST, and C1SL Versions
5-24 CENTRON Meter Technical Reference Guide
Figure 5.8 CENTRON C1ST/L Battery Life
An explanation of Figure 5.8 is as follows:
The Available Battery Capacity line is a function of time. Recent changes made to
the design (optimized battery current consumption at the transition phase from AC
power ON to AC power OFF), allowed the CENTRON to further improve the
available battery budget over time.
With the estimated available battery capacity, a carryover capacity of 8 years is
shown by the cross over point between the Available Battery Capacity curve and
the Battery Usage when the meter is not powered curve.
A very small amount of current is required to keep the real time clock running
when the meter is not powered from the AC line. The clock is running from
battery power (when not powered from the AC line) when the meter is
programmed with a TOU or LP configuration that requires clock or calendar
functionality. An even smaller amount of current is required of the battery while
the meter is powered or is in low power mode. The meter is in low power mode
when the meter is programmed with a demand only configuration (no clock or
calendar functions) or when given a three button reset. The lower Current Draw
AC Power line on Figure 5.8 represents this lowest current (low power mode or AC
power). When the meter is either powered from the beginning of life or in low
power mode, the available battery capacity is not used until beyond 15 years of
service life.
The series of lines is intended to help the user to assess the battery life under
different usage profiles (time while the meter is not powered versus time while the
meter is powered).
The following examples illustrate usage of the below Battery Life Graph.
Example 1
For example 1 (see Figure 5.9), the meter is unpowered (with battery running the
clock) for two years then installed in the field under AC power. Follow the Current
Draw: the Battery Power line from year zero to year two, then follow the Current
Draw: the AC Power line from year 2 to the right. This shows that the battery will