UPS Battery Voltage, Capacity and Runtime Guide
Understand UPS battery voltage, battery capacity and backup time before selecting replacement batteries or an external battery configuration.
Battery voltage and UPS DC voltage
A battery’s nominal voltage and the UPS DC string voltage are different specifications. Batteries connected in series add voltage. The permitted number and arrangement must match the UPS design and charging system. Review UPS battery specifications before selecting a replacement.
Capacity does not directly determine runtime
Ampere-hour capacity is measured under stated discharge conditions. UPS runtime also depends on actual load, discharge rate, temperature, battery condition, cutoff voltage and conversion losses. Use model-specific runtime curves or discharge tables rather than promising a fixed number of hours from Ah alone.
Requirements such as 1, 8, 12 or 24 hours
Long backup-time requests need a defined operating load and an approved battery configuration. A larger battery arrangement must also be compatible with the UPS charger and DC system. State the target duration as a requirement to assess, not a guaranteed runtime based only on capacity.
VRLA batteries and external battery packs
A loose VRLA battery, an assembled battery string and a proprietary external battery module are different products. Match chemistry, voltage, terminals, enclosure, communication requirements and supported battery count. Same-voltage batteries can have different dimensions and discharge characteristics.
Replacement versus runtime extension
For replacement, provide the UPS model, existing battery labels and battery count. For longer runtime, also provide measured load and the new target duration. Review battery replacement planning or UPS runtime extension.
Use the technical documents
Download the applicable datasheet or specification file from the product’s Documents tab or the document library. Compare the discharge conditions and revision before using a table for selection.
Discuss your product requirements.
Send the brand, model, quantity and delivery destination.