User`s manual

Maintenance and inspection Battery life and replacement procedure
10 – 14
SRAM card battery
Q2MEM-BAT
The life time of the battery Q2MEM-BAT depends on the used memory board and on the time,
the CPU is switched ON. Additionally it depends on the serial number (version) of the CPU.
Tab. 10-14:Battery life (Q2MEM-BAT) when the SRAM card is installed in CPU modules with
the serial No. (first digits) is "04012" or later
The power-on time ratio indicates the ratio of programmable controller power-on time to one day (24 hours).
When the total power-on time is 12 hours and the total power-off time is 12 hours, the power-on time ratio is 50 %.
The actual value may vary depending on ambient temperature.
NOTES Do not use the battery exceeding the guaranteed value of the battery life.
If the battery life for data buffering has expired the guaranteed time of the following table,
store program and data into a ROM, so that the data don’t get lost, if the PLC is powered
down or the battery voltage is low,
during the time given in the right column of the following table, save program and data on
a PC, after special relay SM52 is set.
Note that the SRAM card battery is consumed even while the programmable controller is
powered ON with the CPU module battery connected.
When the battery-low special relay SM52 turned on, immediately change the battery. Even if
an alarm has not yet occurred, it is recommended to replace the battery periodically accord-
ing to the operating condition.
The SRAM card is not available for the Basic model QCPU.
SRAM card
Power-on
time ratio
Battery life
Guaranteed value Actual service value After SM51 turned on
Q2MEM-1MBS
Q2MEM-2MBS
0 % 690 hours
(28 days)
6336 hours
(0.72 years)
8 hours
100 % 11784 hours
(1.34 years)
13872 hours
(1.58 years)
8 hours
Tab. 10-13:Battery life (Q2MEM-BAT) when the SRAM card is installed in CPU modules with
the serial No. (first digits) is "04011" or earlier
SRAM card
Power-on
time ratio
Battery life
Guaranteed value
Actual service value
After SM52 turned on
Q2MEM-1MBS
(Manufacturing
control No. A)
0 % 690 hours
(28 days)
6336 hours
(0.72 years)
8 hours
100 % 11784 hours
(1.34 years)
13872 hours
(1.58 years)
Q2MEM-1MBS
(Manufacturing
control No. B)
Q2MEM-2MBS
0 % 2400 hours
(0.27 years)
23660 hours
(2.7 years)
20 hours
30 % 2880 hours
(0.32 years)
31540 hours
(3.6 years)
50 % 4320 hours
(0.49 years)
39420 hours
(4.5 years)
70 % 6480 hours
(0.73 years)
43800 hours
(5 years)
100 % 43800 hours
(5 years)
43800 hours
(5 years)
50 hours