How Long Will a UPS Run an NVR and Security Cameras?
Estimate UPS runtime for an NVR camera system from real watts, battery watt-hours, inverter efficiency and reserve margin.
UPS runtime depends on attached watts and usable battery energy. The VA rating alone cannot tell you how long an NVR and cameras will run.
Simple energy estimate
If the UPS battery system has roughly 180Wh of nominal stored energy, only part of that is practically delivered at AC output after inverter losses, discharge-rate effects and cutoff reserve. Assuming 70% usable energy gives about 126Wh. At a 100W surveillance load, the simplified estimate is about 1.26 hours.
Why manufacturer runtime curves are better
UPS batteries do not behave like ideal energy tanks. Higher loads reduce effective capacity and UPS electronics consume power. For a final purchase, use the manufacturer's runtime curve at the expected load.
Reduce load before buying a huge battery
A 35W monitor, desktop PC or unnecessary PoE device can materially reduce runtime. If the goal is recording continuity, prioritize cameras, NVR, switch and essential networking.
Plan for battery aging
Runtime declines as batteries age. A system that barely achieves the required outage duration when new may fail the requirement after a few years. Include margin and test periodically.
Example design target
Suppose the complete camera chain averages 140W and you need 30 minutes. The ideal energy requirement is 70Wh; after allowing for conversion losses and reserve, the battery system should contain materially more usable capacity than that. Then verify the actual UPS runtime curve at 140W.
Use the UPS Runtime Calculator for a quick model.