User`s manual

Battery life and replacement procedure Maintenance and inspection
MELSEC System Q, Hardware 10 – 13

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 %.

refer to Tab. 10-5

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.
Q10UD(E)HCPU
Q13UD(E)HCPU
Q20UD(E)HCPU
Q26UD(E)HCPU
0 %
1
43800 hours
(5 years)
43800 hours
(5 years)
600 hours
(25 days)
30 %
50 %
70 %
100 %
0 %
2
11100 hours
(1.27 years)
43800 hours
(5 years)
600 hours
(25 days)
30 % 15800 hours
(1.80 years)
50 % 22000 hours
(2.53 years)
70 % 37000 hours
(4.22 years)
100 % 43800 hours
(5 years)
0 %
3
5000 hours
(0.57 years)
43800 hours
(5 years)
600 hours
(25 days)
30 % 7100 hours
(0.81 years)
50 % 10000 hours
(1.14 years)
70 % 16600 hours
(1.89 years)
100 % 43800 hours
(5 years)
0 %
4
3700 hours
(0.42 years)
36100 hours
(4.12 years)
432 hours
(18 days)
30 % 5200 hours
(0.59 years)
43800 hours
(5 years)
50 % 7400 hours
(0.84 years)
70 % 12300 hours
(1.40 years)
100 % 43800 hours
(5 years)
CPU
Power-on
time ratio

Battery con-
sumption
category

Battery life (Q7BAT)
Guaranteed value

Actual service
value

After SM52
turned on

Tab. 10-12:Battery (Q7BAT) lives of the Universal model QCPU