Mitsubishi Electric Q172DCPU User Manual page 152

6 INSPECTION AND MAINTENANCE
POINT
(1) Do not use the battery exceeding its guaranteed life.
(2) When the battery hours (total power failure time) may exceed its guaranteed
value, take the following measure.
• Perform ROM operation to protect a program even if the battery dies at the
Multiple CPU system power-OFF.
• If SM51 or SM52 turns on, the contents of programs, parameters and
absolute position data cannot be guaranteed.
It is recommended to back-up the battery periodically.
(3) When the battery-low special relay SM52 turns on, immediately change the
battery. Even if the alarm has not yet occurred, it is recommended to replace
the battery periodically according to the operating condition
(4) The self-discharge influences the life of battery without the connection to
Q173DCPU/Q172DCPU/Q172DEX. The external battery should be exchanged
approximately every 4 or 5 years.
And, exchange the battery with a new one in 4 to 5 years even if a total power
failure time is guaranteed value or less.
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