The amount of UPS battery runtime a data center needs depends on the critical load, the facility’s backup-power design, how quickly generator power becomes available and the operating requirements of the site. There is no single runtime that is appropriate for every data center.
In a generator-backed facility, the UPS battery system typically provides the stored energy needed to support the critical load during the transition from normal utility power to backup generation. Battery capacity can then be configured around the facility’s required runtime and UPS load.
Critical Infrastructure Group provides UPS battery testing and replacement services and supplies UPS systems for data center and mission-critical applications.
UPS Runtime Should Match the Data Center’s Power Strategy
The first question is what the UPS battery system is expected to accomplish during a power interruption.
For many data centers with standby generators, the battery system acts as a bridge. It supports the protected load immediately while the facility’s backup generation and transfer equipment transition the data center to its alternate power source.
U.S. Department of Energy data center power-system research describes this arrangement directly: on-site generation provides longer-duration backup power while UPS batteries supply the load during the interim period between a grid disturbance and the availability of local generation.
Review the U.S. Department of Energy’s data center power-system modeling research.
That means the appropriate runtime should be coordinated with the generator and transfer-system design rather than selected independently.
The Protected Load Directly Affects Battery Runtime
Battery runtime depends on how much load the UPS is supporting. As the protected load changes, the amount of runtime available from a given battery configuration changes as well.
This is especially important when an existing data center adds servers, storage, networking equipment, high-density racks or AI/GPU infrastructure. The UPS itself may have sufficient power capacity for the expansion while the battery configuration may need to be reviewed to maintain the desired runtime.
If UPS capacity is also being evaluated, see What Size UPS Does a Data Center Need?
For expansion projects, CI Group can help source additional or replacement UPS equipment across a broad range of capacities and manufacturers.
Generator Start and Transfer Time Are Part of the Calculation
In a data center with backup generation, the battery system and generator system work together.
The UPS provides uninterrupted power while the generator starts, reaches the required operating condition and the electrical system transfers the critical load to the backup source. The desired battery runtime should provide appropriate support for that transition as defined by the facility’s engineering and operating requirements.
Facilities evaluating backup generation can also review How Do You Size a Backup Generator for a Data Center?
CI Group supplies commercial and industrial generators, including large-capacity equipment for data center and critical-infrastructure applications.
More Runtime Can Be Added When the Application Requires It
Some facilities want additional battery runtime beyond the basic transition to generator power. The appropriate configuration depends on the UPS model, battery technology, available space and project requirements.
Depending on the UPS architecture, increased runtime may be supported through a larger battery system, additional compatible battery cabinets or strings, or a replacement battery configuration designed around the required load and runtime.
This gives data center operators an opportunity to specify runtime around the way the facility actually operates rather than treating battery capacity as a fixed characteristic of the UPS.
When planning a new system, CI Group can help identify UPS equipment and compatible battery configurations that fit the required capacity, voltage and project requirements.
Existing Battery Systems Can Be Evaluated for Current Runtime Requirements
A data center expansion is also a good time to review the battery system already supporting the UPS.
The review can compare the current protected load with the facility’s desired runtime and determine whether the existing configuration continues to match the operating requirement. Battery testing can provide additional information about the condition and performance of the installed system.
If additional capacity is appropriate, CI Group can support UPS battery testing and replacement as part of a data center maintenance, expansion or equipment-update project.
Battery Maintenance Helps Preserve the Intended Runtime
Once a battery system is sized for the required runtime, ongoing inspection and testing help confirm that the installed system continues to support the facility’s critical-power plan.
NFPA 70B is the current standard for electrical equipment maintenance and includes maintenance requirements applicable to stationary standby battery systems and other electrical equipment used in commercial and critical facilities.
Learn more about NFPA 70B electrical equipment maintenance requirements.
CI Group’s UPS Maintenance Services can incorporate UPS and battery-system evaluation into an ongoing critical-power maintenance program.
For more information about service intervals, see How Often Should a Data Center UPS Be Maintained?
What Determines Data Center UPS Battery Runtime?
When planning battery capacity, the project team should consider:
- The critical load supported by the UPS
- The desired minimum runtime at that load
- Generator startup and transfer requirements
- UPS and battery-system configuration
- Existing battery capacity and condition
- Required redundancy
- Planned increases in IT load
- AI, GPU or other high-density computing additions
- Available space for battery cabinets or supporting equipment
- Manufacturer requirements for the selected UPS system
Once the load and required runtime are established, the appropriate UPS and battery configuration can be selected for the application.
Plan Battery Capacity With the Entire Critical-Power System
UPS battery runtime works best when it is planned as part of the complete data center power system. The UPS, batteries, generators and transfer equipment all contribute to maintaining power from the moment normal service is interrupted through the transition to longer-duration backup generation.
For facilities building, expanding or updating critical-power infrastructure, CI Group can provide UPS equipment, battery replacement, generator equipment, automatic transfer switches and related critical-power support through its Data Center Power Infrastructure services.
Need More UPS Battery Runtime for Your Data Center?
Talk with CI Group about your UPS load, desired runtime, existing battery configuration and project requirements. We can help identify battery replacement, expansion and UPS equipment options for your facility.