6 Inspection and Maintenance
6-4
NJ-series CPU Unit Hardware User’s Manual (W500)
6-2 Replacing the Battery
The Battery in the NJ-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 the variables that are retained
during power interruptions.) This section describes how to replace the Battery.
The Battery maintains the CPU Unit internal clock and the variables retained during power interruptions
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 variables that are retained for power interruptions will be lost when the
main power supply goes OFF.
* The minimum lifetime is the memory backup time at an ambient temperature of 55C. The typical lifetime is the
memory backup time at an ambient temperature of 25C.
6-2-1 Battery Replacement
Purpose of the Battery
Battery Service Life and Replacement Period
Model
Approx. maximum
lifetime
Approx. minimum lifetime
*
Approx. typical lifetime
*
NJ501- 5 years 1.1 years 5 years
NJ301- 5 years 2 years 5 years
NJ101- 5 years 2 years 5 years
Memory Backup Time
5 yr
4 yr
3 yr
2 yr
1 yr
Ambient temperature
25
°
C40
°
C
* This graphic is for reference only.
This is the value when the power ON time rate is 0% (power OFF).
55
°
C
NJ101- CPU Unit
NJ301- CPU Unit
NJ501- CPU Unit
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