The cRIO-904x contains a CMOS battery. The CMOS battery is a lithium cell battery that stores the system clock information when the cRIO-904x is powered off. There is only a slight drain on the CMOS battery when power is applied to the cRIO-904x power connector. The rate at which the CMOS battery drains when power is disconnected depends on the ambient storage temperature. For longer battery life, store the cRIO-904x at a cooler temperature and apply power to the power connector. Refer to the specifications in the Models section or on ni.com/manuals for the expected battery lifetime.
The CMOS BATTERY IS DEAD warning appears onscreen during the power-on self test if the battery is dead. The cRIO-904x still starts, but the system clock is reset to the date and time of the BIOS release. The battery is not user-replaceable. If you need to replace the CMOS battery, contact NI. Refer to the specifications in the Models section or on ni.com/manuals for information about battery disposal.