Backup power explainers
UPS for Router and Modem Runtime Planning
A router and modem usually draw far less power than a computer, which makes them good candidates for long UPS runtime. The key is adding every network device in the chain, including fiber boxes, switches, mesh nodes, and any small adapters.
Comparison
Small UPS
Best for: Basic modem and router support during short outages.
Tradeoff: Runtime may drop quickly if extra network devices are added.
Larger UPS
Best for: Mesh systems, fiber ONT, switches, and longer work-from-home continuity.
Tradeoff: Costs more and may still provide less runtime than a larger power station.
DC battery backup
Best for: Compatible routers or fiber equipment with low-voltage inputs.
Tradeoff: Requires exact voltage and connector matching.
Sizing example
A 35 W load for 8 hours points to about 350-500 Wh before adding reserve and real-world losses.
A modem, router, and small fiber terminal may average 35 watts. UPS runtime depends on usable battery capacity and inverter efficiency at low load.
Decision checklist
- Add the watts for modem, router, ONT, switches, and mesh nodes.
- Choose runtime based on the longest outage you want to bridge.
- Check whether internet service stays active during local power outages.
- Keep the UPS in a ventilated place.
- Test the setup before relying on it for remote work.
Planning notes
- Low loads can still be inefficient on some AC UPS units.
- A fiber ONT may be required for the router to have service.
- Mesh satellites may need separate backup power if they are in different rooms.
- Cellular hotspot backup may be useful when wired service fails upstream.
Safety and limits
- Do not overload UPS outlets with unrelated devices.
- Replace UPS batteries according to the device guidance.
- Avoid placing battery backup equipment in enclosed hot cabinets.
- Use the correct power adapters for network equipment.
FAQ
How long will a UPS run a router and modem?
Small network loads may run from under an hour to many hours depending on UPS battery size, load watts, and efficiency.
Should I put my desktop computer on the same UPS?
Only if the UPS is sized for it. A desktop can cut router runtime dramatically.
Will internet still work in a power outage?
It depends on your provider's upstream equipment and connection type. Your home gear may have power while service outside your home is unavailable.