Robot controller does not have a memory backup battery. However, it  contains a battery that maintains the date and time of the internal  clock.

If the controller is turned off when the battery is low, the internal  clock will be initialized. In this case, the time and date will be  displayed incorrectly, and the Change Battery error will be erroneously  displayed. In addition, an error might occur, leading to immediate stop  during motion. 


The lifetime of the internal clock battery is 10 years. At the biennial inspection, check that the battery's replacement timing. If the replacement timing is prior to the next inspection, before the replacement timing elapses, please contact DENSO Robot service division or a dealer where you have purchased our robot. 


For how to confirm the battery replacement date, refer to "Displaying and Changing Controller Battery Maintenance Schedule Screen" in TEACH PENDANT OPERATION GUIDE or "Setting the next Battery Replacement Date" in MINI PENDANT OPERATION GUIDE.

Owner's Manual

https://www.fa-manuals.denso-wave.com/en/usermanuals/005907/