Coin cell Real Time Clock (RTC) battery reports low or high voltage state incorrectly

EMS Event Logs

• EMS event log events will show similar to the following:

[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
 

[env_mgr: monitor.rtcHighPower:error]: Real-time clock battery voltage is above normal (P3.3V Batt is warning high (3307 mV).)

[node1: env_mgr: monitor.rtcWarnLowPower:error]: Real-time clock battery voltage is below normal (2880 mV).

Sensors State

• The 3 volt battery sensor will show in an alert state:

cluster1::> system node environment sensors show -state !normal

Sensor Name              State          Current    Critical     Warning     Warning    Critical
                                        Reading       Low         Low         High       High
-------------------------------------------------------------------------------------------------
Bat 3.0V                 critlow         2545 mV     2545 mV     2702 mV     3503 mV     3575 mV

or:

P3V Batt                 warnlow         2880 mV     2720 mV     2880 mV     3300 mV     3460 mV 

• The system controller service-event show command also shows the fault.

cluster1::> system controller service-event show

Node             ID  Event Location                      Event Description
---------------- --- ----------------------------------  ----------------------
cluster1-01      1   Controller B on Chassis 1           P3V3_BATT: Voltage Sensor 26 UNC

• The BMC CLI system sensors and events all commands or the corresponding SP-LATEST-IPMI and SP-LATEST-SYSLOG AutoSupport sections will also indicate the issue:

BMC> system sensors filter BAT

Sensor Name      | Current    | Unit       | Status     | LCR       | LNC       | UNC       | UCR
-----------------+------------+------------+------------+-----------+-----------+-----------+-----------
P3V_BATT         | 2.840      | Volts      | nc         | 2.720     | 2.880     | 3.300     | 3.460

BMC> events all

Record 904: Wed Mar 18 02:14:02.350000 2020 [IPMI.notice]: 0001 | 02 | EVT: 0157bdbd | P3V3_BATT | Assertion Event, "Upper Non-critical going high" | Reading: 3.307 | Threshold: 3.307
 

Or

Record 1946: Sun May 29 23:44:14 2022 [IPMI.notice]: 6501 | 02 | EVT: 0150bdbd | Bat_3.0V | Assertion Event, "Lower Non-critical going low"

 

Controller Attention LED

• The amber warning  attention LED on the controller will illuminate