Battery Back-Up; Internal Battery; Internal Battery Monitoring - Elster A1140 User Manual

19

BATTERY BACK-UP

The A1120/40 has an internal battery that supports the clock and calendar.
An optional external battery that supports the reading of meter data and display facilities during
power outages can be provided.
19.1

Internal Battery

In the event of an a.c. failure, an internal battery (a Lithium 'coin' cell) supports the real time
clock.
The battery is soldered onto the printed circuit board.
The meter can be programmed to initiate one of the following courses of action should the supply
fail and the battery become exhausted. When the supply returns: -
a. Freeze the TOU registers and increment the total cumulative registers only
b. Assume the last known time and continue to use the TOU registers
See Section 29 for battery disposal.
19.1.1

Internal Battery Monitoring

The battery provides support for the life of the meter. The following functions are provided on the
Battery Monitor: -
Elapsed Time - The total amount of battery support time is monitored. The elapsed time counter
decrements to represent the use/shelf life of the battery.
Remaining Time - The remaining battery life is calculated by subtracting the elapsed time from
the expected time. The remaining life may be read via the optical or RS232 communications port
and its value optionally included in the display sequence.
If the remaining time falls to zero, a 'flag' is set which can be read by via the optical port or RS232
port.
Failed Battery - The occurrence of total battery fail is monitored each time the meter is
energised. A flag is set and the time and date recorded when the meter last powered down.
Operating & Maintenance Instructions
31