PowerEdge: AC Power Recovery Setting Fails After CMOS Battery Failed or Removed

Unexpected Power‑On Behavior on PowerEdge 14G/15G/16GIntel Platforms

When the CMOS battery has failed or been removed, the AC Power Recovery BIOS setting no longer controls the system’s power‑on response.

• The server powers on automatically when AC power is applied.
• This occurs regardless of the configured AC Power Recovery option (Off, On, Last).

The AC Power Recovery configuration is stored in a chipset register. When the CMOS battery fails or is removed, the register loses its stored value and reverts to the default setting.

This reset causes the system to ignore the configured AC Power Recovery option and always power on automatically.

Replace CMOS Battery to Restore AC Power Recovery Setting.

Warning: Performing hardware replacement without proper power isolation can cause electric shock or damage to components. Always unplug the server before opening the chassis.

Caution: Static discharge may damage the motherboard. Use an anti‑static wrist strap or mat throughout the procedure.

Note: Use only the battery type recommended by Dell for your specific PowerEdge model. Installing an incorrect battery may lead to further BIOS configuration loss.

Contact Dell Support: If you are unsure about any step, encounter unexpected behavior, or the issue persists after battery replacement, contact Dell Technical Support for assistance.