To estimate WiFi router runtime, total the power of every device needed for the connection and divide usable battery energy by the average demand. Keeping a router powered does not guarantee that your internet provider stays online.
Editorial correction: Earlier versions included unsupported testing, experience or performance claims. This research guide replaces those claims. Examples below are calculations, not measurements made by Wild Smart Gear.
Include the complete network
- Router and any separate WiFi access points.
- Cable modem, fiber ONT or other provider equipment that needs local power.
- Switches, mesh nodes and any required PoE adapters.
- The actual power supplies or supported DC converters.
An adapter’s maximum output rating is not necessarily the device’s average consumption. Measure the intended arrangement or obtain device-specific consumption information.
Calculate an example
Suppose a measured router uses 8W and a modem uses 12W: together they average 20W. A hypothetical 400Wh delivered to those devices would provide 20 hours at that load before reserve. These are assumed inputs, not measurements by this site.
If the inverter consumes additional energy that is not included in the measured usable Wh, account for that overhead. Avoid counting the same conversion losses twice. A station may turn an output off under light load, so check its idle-timeout settings and manual.
Check DC connections rather than guessing
A DC cable fitting the router does not prove voltage, polarity or current compatibility. Use the device’s supported supply arrangement and station output limits. USB-C PD requires an agreed supported profile and cable; it is not a universal router adapter.
Choose runtime versus UPS behavior
If interruption tolerance matters, check the complete manufacturer-supported UPS/EPS arrangement and transfer time against the network equipment. An EPS label is not a guarantee that every modem stays running through transfer.
Use the outage continuity guide to plan provider availability, charging, automatic restart and alternatives. This page covers energy calculations, not a promise of uninterrupted internet.