RTC Battery Fault

Applies to

• FAS/AFF Platforms
• Real-time clock (RTC) coin-cell battery

Issue

• Node and chassis fault LEDs are illuminated with error below:

hsamcmd --fault-show-all
===============================
tag  origin  fld                                     fault reason                                    count  time
---- ------- ----                                    -------------                                   ------ -----
1    bmc     /chassis-1/controller-a                 P3V3_BATT: Voltage Sensor 26 LNC                1      Wed Jun 25 10:58:10 2025
2    bmc     /chassis-1/controller-a                 P3V3_BATT: Voltage Sensor 26 LCR                1      Wed Jun 25 10:58:22 2025

• Or node and chassis fault LEDs are illuminated with no clear indication of the fault
• The following EMS message is generated, and a non-critical fault will be reported against the battery:

Tue Sep  4 15:05:29 CEST [NODE1:monitor.chassisPower.degraded:warning]: Chassis power is degraded: RTC Battery is in WARN LOW state current voltage is 2774 mV, normal low is 2800 mV

• SP-LATEST-IPMI log shows P3.3V Batt is the the following condition.

P3.3V Batt     warnlow    2660 mV     2537 mV     2695 mV     3307 mV     3447 mV    

Or

P3.3V Batt     critlow     945 mV     2100 mV     2205 mV     3395 mV     3500 mV

• SP-LATEST-SYSLOG log shows rtcWarnLowPower

BMC env_mgr[1534]: Payload EMS: EMS_monitor_rtcWarnLowPower(2660 mV) 

• BMC events all shows P3.3V Batt is critical low.

BMC env_mgr[1461]: P3.3V Batt is critical low

• From the BMC/SP shows P3V_BAT is the following condition:

Sensor Name      | Current    | Unit       | Status     | LCR       | LNC       | UNC       | UCR
-----------------+------------+------------+------------+-----------+-----------+-----------+-----------
P3V_BATT         | 2.840      | Volts      | nc         | 2.720     | 2.880     | 3.300     | 3.460
Or
P3V3_BATT        | 0.963      | Volts      | cr         | 2.100     | 2.205     | 3.395     | 3.500