Certified - CompTIA Server+

The complementary metal oxide semiconductor battery powers the basic input output system chip on a server’s motherboard. This chip stores low-level configuration data such as boot device order, virtualization settings, and system time. When the server is powered off, the complementary metal oxide semiconductor battery keeps this data intact. If the battery fails, these settings may be lost. The Server Plus certification includes knowledge of how battery failures affect server reliability and how to identify and respond to these problems.
Failure of the complementary metal oxide semiconductor battery can cause unpredictable system behavior. The system may reset its date and time after each reboot. Boot errors may occur because device order or startup behavior has been changed. System freezes or lockups may appear randomly. Many of these symptoms remain hidden until the battery is fully depleted. Timely monitoring and replacement prevent these failures from affecting uptime or triggering unnecessary support incidents.
The most recognizable sign of battery failure is an incorrect system clock after reboot. The server may display a date from the past or revert to a default year such as two thousand and one. Settings within the basic input output system may also return to their factory defaults. This can include turning off virtualization support, changing the boot order, or disabling necessary controllers. Boot failures, including those related to security keys or encrypted disks, may also occur if the system clock is invalid.
The real-time clock, also known as the R T C, is used by operating systems, authentication systems, and encrypted volumes. Many server applications depend on accurate timestamps. An invalid system time can prevent secure logins, cause software updates to fail, or render certificates invalid. On some platforms, a completely dead battery will block the boot process entirely until the basic input output system is manually reconfigured.
Battery voltage readings are available in most systems. They can be found inside the basic input output system menu or through management software such as Intelligent Platform Management Interface tools. Warning signs include voltage readings below two point five volts or a system that resets its clock unexpectedly. If the server is rebooted and the time is wrong, the battery may already be too weak to hold the configuration.
Replacing the complementary metal oxide semiconductor battery must be done carefully. The server must be powered down completely and unplugged from power. Electrostatic discharge precautions must be followed, and the battery must be inserted in the correct orientation. Most servers use a lithium battery with a model number C R two zero three two. Always use a replacement part recommended by the system vendor.
After replacing the battery, the system may revert to default settings. Technicians must reconfigure all critical basic input output system options. This includes restoring the boot device order, enabling virtualization extensions, and confirming system timers. If possible, settings should be backed up before battery failure occurs. Printouts, screenshots, or exported configuration files are helpful for restoring complex settings.
Loss of accurate time can interfere with scheduled tasks. Backup jobs, system update tasks, or scheduled scripts may fail if the system clock is incorrect. Security certificates may be seen as invalid if their timestamps appear to be in the future or past. After any battery-related event, timestamps should be corrected as soon as the system boots. Services should then be restarted to confirm normal function.
Some random system lockups can be traced to real-time clock issues. When the system loses time synchronization, services may hang or become unresponsive. Review system logs, basic input output system event reports, and the behavior of the network time protocol service. If errors appear around time sync, this may confirm that the battery or R T C has failed. Fixing the clock often restores normal operation.
When a battery is replaced, the event must be recorded. Maintenance logs should include the battery model, server identifier, and time of replacement. Tracking battery age helps predict future replacement needs. Recording each event also supports warranty tracking and helps correlate unusual system behavior with battery-related changes.
For more cyber related content and books, please check out cyber author dot me. Also, there are other prepcasts on Cybersecurity and more at Bare Metal Cyber dot com.
Preventing system instability from battery failure begins with routine health checks. During quarterly hardware inspections, technicians should verify the voltage of the complementary metal oxide semiconductor battery. Batteries should be replaced every three to five years, even if no warning signs are present. Proactive replacement avoids service disruption during reboots or after unexpected power outages. Waiting until failure risks data loss, misconfigured systems, or unplanned downtime.
Some issues that resemble battery failure may have different root causes. These include corrupted firmware, a failed basic input output system flash, or a defective power supply. Battery problems often appear alongside other symptoms in aging hardware. Always rule out layered causes when troubleshooting unexplained boot behavior. Restarting the system repeatedly without identifying the cause may lead to further instability.
Modern servers include tools for detecting battery or real-time clock issues. The basic input output system event log may include error messages about date resets or invalid configuration values. Intelligent Platform Management Interface systems can forward alerts to centralized monitoring platforms. Technicians should review these alerts as part of monthly maintenance. Enabling Simple Network Management Protocol traps or syslog forwarding can improve visibility into low-level issues.
After replacing a battery, it is important to review and reapply the server’s power recovery settings. These determine what the server does after power is restored. Options include remaining off, returning to the last state, or turning on automatically. Battery failure may reset this configuration. The chosen setting should match the organization's policy and be documented in standard build templates for consistency.
Battery replacements should be aligned with other planned maintenance. When possible, combine battery checks with fan inspection, power supply testing, and thermal system cleaning. This minimizes the number of reboots and downtime periods needed for maintenance. Coordinating tasks also allows for better use of scheduled windows and technician availability, especially in production environments.
Technicians must avoid unsafe replacement methods. Never solder batteries to the board or install batteries with unmatched voltage ratings. Use manufacturer-recommended parts and replace one battery at a time, especially in systems that use clustering or high availability. Unapproved methods may void warranties or introduce dangerous conditions. All replacements should be documented according to vendor policy.
Training support staff to understand low-level hardware health improves overall reliability. Include instruction on how the basic input output system depends on battery power, how to identify related symptoms, and how to properly perform replacements. Troubleshooting flowcharts should include battery-related checks. This knowledge should be added to onboarding materials for new technical staff.
In conclusion, the complementary metal oxide semiconductor battery is a small component with significant responsibility. Its failure can lead to misconfiguration, boot errors, and unpredictable behavior. Regular inspection, accurate documentation, and safe replacement ensure stability and help maintain server uptime. The next episode explores startup-related security failures, including Trusted Platform Module errors and firmware integrity alerts.