User`s manual

Battery life and replacement procedure Maintenance and inspection
MELSEC System Q, Hardware 10 – 11
● Q02(H)-, Q06H-, Q12H- or Q25HCPU (first digits of serial No. is "05011..." or later), Process
CPU (QPHCPU) and Redundant CPU (QPRHCPU)

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 guaranteed value represents a battery life at 70 °C, which is calculated based on the characteristic values of
manufacturer-supplied memories (SRAM) and on the assumption of storage within the ambient temperature
range of –25 °C to 75 °C (operating ambient temperature of 0 °C to 55 °C).

The actual service value (reference value) represents a battery life that is calculated based on the values meas-
ured at storage ambient temperature of 40 °C. This value is intended for reference only, as it varies with charac-
teristics of the memory.

In the following status, the backup time after power off is 3 minutes:
– The battery connector is disconnected.
– The lead wire of the battery is broken.
CPU
Power-on
time ratio

Battery life (Q7BAT)
Guaranteed value

Actual service value

After SM52 turned on

Q02CPU 0 % 43800 hours
(5 years)
43800 hours
(5 years)
240 hours (10 days)
30 %
50 %
70 %
100 %
Q02HCPU
Q06HCPU
0 % 5000 hours
(0.57 years)
43800 hours
(5 years)
240 hours (10 days)
30 % 7142 hours
(0.81 years)
50 % 10000 hours
(1.14 years)
70 % 16666 hours
(1.90 years)
100 % 43800 hours
(5 years)
Q02PHCPU
Q06PHCPU
0 % 4051 hours
(0.46 years)
38727 hours
(4.42 years)
192 hours (8 days)
30 % 5787 hours
(0.66 years)
43800 hours
(5 years)
50 % 8102 hours
(0.92 years)
70 % 13503 hours
(1.54 years)
100 % 43800 hours
(5 years)
Q12HCPU
Q25HCPU
Q12PHCPU
Q25PHCPU
Q12PRHCPU
Q25PRHCPU
0 % 2900 hours
(0.33 years)
21107 hours
(2.40 years)
96 hours (4 days)
30 % 4142 hours
(0.47 years)
30153 hours
(3.44 years)
50 % 5800 hours
(0.66 years)
42214 hours
(4.81 years)
70 % 9666 hours
(1.10 years)
43800 hours
(5 years)
100 % 43800 hours
(5 years)
Tab. 10-11:Battery (Q7BAT) lives of High performance model QCPU (first digits of serial No. is
"05011..." or later), Process CPU and Redundant CPU