PowerEdge: Coin-cell (CMOS) battery changes

What does the coin-cell battery do?

The coin-cell battery provides backup power for two system features when the main input power is removed:

1. Preserving the real-time clock (RTC).
2. Enabling the chassis intrusion feature that alerts when the system has been opened.

When the coin-cell battery falls below a certain level, these two features do not function.

Furthermore, on platforms with Intel processors, the coin-cell battery did impact the system settings. Although settings are stored in non-volatile memory, for consistency with prior behaviors and user expectations, removing the coin-cell battery would have reset those settings to defaults.

The changes below were introduced for PowerEdge 14G in iDRAC 7.00.00.173 and in Intel BIOS versions 2.22.1 (for 400-series servers and above) and 2.17.2 (for 100-300 series servers) in mid-August 2024.

However, these two BIOS releases were demoted from the Dell support site in September due to an unrelated sighting. BIOS versions 2.22.2 and 2.17.3 replaced them respectively on October 1.

Similar changes have been applied to 15G and newer platforms starting from the firmware combinations below.  While these are the versions where the change was made, see PowerEdge: Minimum, Recommended, and Latest Code Versions when selecting a release to install.
 

Platform	BIOS	iDRAC
14G AMD	Not Implemented	7.00.00.173
14G Intel 100-300 series	2.17.3	7.00.00.173
14G Intel 400+ series	2.22.1	7.00.00.173
15G AMD	2.18.1	7.20.10.05
15G Intel 100-300 series	1.11.1	7.20.10.05
15G Intel 400+ series	1.16.2	7.20.10.05
16G AMD	1.11.2	7.20.10.05
16G Intel 100-300 series	2.0.0	7.20.10.05
16G Intel 400+ series	2.5.4	7.20.10.05

Recommended Action:

Dell Technologies recommends all 14G customers update to iDRAC 7.00.00.173 or newer. Customers with Intel-based products should also apply BIOS versions 2.22.2 or newer (for 400-series and above servers) or 2.17.3 or above (for 100-300 series). Together these provide the best experience.

Changes:

iDRAC 7.00.00.173 and BIOS versions 2.22.1 (400-series and above) and 2.17.2 (100-300 series) change these behaviors. The expectation is that for most users, the impact of replacing the battery, which requires an outage window, is not worthwhile.

Settings preservation:

With the updated BIOS, removing the coin-cell battery no longer resets BIOS settings. This aligns the behavior with AMD-based PowerEdge products.

NVRAM can still be cleared with the jumpers on the main board.

Previous event logging:

The previous designed behavior logs a warning event, BAT0015, when the coin-cell reaches ~2.7 V. Once it drops to ~2.6 V, a critical event, BAT0017, is logged. Each error is logged to both Lifecycle Log (LCL) and System event log (SEL) event messages.

However, due to a defect, recent firmware has instead reported these events as BAT0020 and BAT0021 respectively. These message codes are intended to be exclusively used for the batteries for non-volatile memory.

Because these events are warning or greater severe, the control panel lights up amber.

When the coin-cell battery drops below ~2.0 V and the system is rebooted, this sequence of events is logged. They appear in both the LCL and on the screen:

• UEFI0034 (critical) indicating battery loss has been detected.
• UEFI0069 (critical) indicating a coin-cell checksum error has resulted in settings being reset.
• UEFI0130 (warning) indicating system time has been lost.

The screen also displays an F1/F2 prompt and waits for the user to acknowledge the errors.

New event logging:

The new behavior results in less messaging overall.

Logging now begins during boot when the coin-cell battery has failed and primary input power was removed. The local system time has already been lost.

With the new BIOS and iDRAC firmware together, an informational event, UEFI0447, is logged to the Lifecycle Log during boot. It advises the user that system time was lost. This single event replaces the three seen on older BIOS versions and there is no longer an F1/F2 prompt during boot. Unless iDRAC is also updated, this event appears as unknown in the Lifecycle Log.

Users dependent on local system time must reset it from F2 System Setup. However, Dell anticipates most customers have configured Network Time Protocol (NTP) on their servers and are not impacted.

With the new iDRAC firmware, an informational event, BAT0022, is logged to the Lifecycle Log when iDRAC boots shortly after input power is connected. It advises that until the coin-cell battery is replaced, chassis intrusion detection will not work when main input power is removed. Be aware that this message will not appear after updating to iDRAC 7.00.00.173 until input power has been lost and then restored. Either removing all power cables and reattaching them or requesting a virtual AC cycle achieves this.

Because both of these new events are informational, the control panel LED remains blue.

Removal of CMOS battery sensor:

As part of implementing the logging changes above, the CMOS battery sensor has been disabled to avoid inconsistencies in health reporting. As a result, the CMOS battery no longer appears in any management interface, including:
iDRAC web UI

• Redfish
• TSR
• RACADM
• SNMP
• IPMI

Summary of changes, using the original 14G Intel implementation as an example:

Defining:

• Old BIOS = < 2.22.x on 400-series and above servers or < 2.17.x on 100-300 series servers
• New BIOS = ≥ 2.22.x on 400-series and above servers or ≥ 2.17.x on 100-300 series servers
• Old iDRAC = < 7.00.00.173
• New iDRAC = ≥ 7.00.00.173

BIOS	iDRAC	BIOS settings when coin-cell low	CMOS sensor	Logged to console during POST	Logged to Lifecycle Log
Old	Old	Lost	Present	UEFI0034, UEFI0069, UEFI0130, Pause for F1/F2	UEFI0034, UEFI0069, UEFI0130 during boot
New	Old	Preserved	Present	Nothing, no pause for F1/F2	Nothing
Old	New	Lost	Not Present	UEFI0034, UEFI0069, UEFI0130, Pause for F1/F2	UEFI0034, UEFI0069, UEFI0130 during boot, BAT0022 when input power has been removed and reapplied.
New	New	Preserved	Not Present	Nothing, no pause for F1/F2	UEFI0447 and BAT0022 when input power has been removed and reapplied.

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