Replacing The Battery; Battery Replacement; Purpose Of The Battery; Battery Service Life And Replacement Period - Omron CJ2 CPU UNIT User Manual

7-2

Replacing the Battery

The Battery in the CJ-series CPU Unit must be replaced periodically as preventative maintenance. (The
Battery is a backup power supply for the CPU Unit's internal clock and RAM). This section describes
how to replace the Battery.
7-2-1

Battery Replacement

Purpose of the Battery

The Battery maintains the CPU Unit internal clock and the I/O memory data held in RAM while the main
power supply is OFF. If the Battery is not installed or Battery voltage drops too low, the internal clock will
stop and the I/O memory data that is held will be lost when the main power supply goes OFF.

Battery Service Life and Replacement Period

At 25°C, the maximum service life for batteries is five years whether or not power is supplied to the CPU
Unit while the battery is installed. The battery's lifetime will be shorter when it is used at higher temper-
atures and when power is not supplied to the CPU Unit for long periods.
The following table shows the approximate minimum lifetimes and typical lifetimes for the backup bat-
tery (total time with power not supplied).
Model
CJ2H-CPU6@(-EIP)
CJ2M-CPU@@
*1 The minimum lifetime is the memory backup time at an ambient temperature of 55°C. The typical lifetime is the
memory backup time at an ambient temperature of 25°C.
Memory Backup Time
5 yr
4 yr
3 yr
2 yr
1 yr
CJ2 CPU Unit Hardware User's Manual
Approx. maximum
Approx. minimum lifetime
lifetime
5 years 1 year 2 months
4 year 5 months
3 year 7 months
CJ2M-CPU@@
25 ° C
40 ° C
This graphic is for reference only.
7 Inspection and Maintenance
*1
5 years
CJ2H-CPU6@(-EIP)
1 year 2 months
Ambient temperature
55 ° C
*1
Typical lifetime
7-5
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