UPS for a router and modem: how long will it last?
A UPS keeps a router and modem on through a short outage. How long depends on the battery, which UPS makers rarely state in watt-hours.
For a 15 W load: a power station with 250–300 Wh is estimated at about 15–16 hours. For the UPS units below the maker lists VA and watts, so a runtime is not published; enter the battery's volts × amp-hours in the calculator, or use the maker's runtime chart. Estimates, not tests.
How long will it run? Estimate, not a test
Hours ≈ battery Wh × efficiency ÷ total watts. The watts below are typical examples, not facts about your gear: read the label on your router's and modem's power adapters.
UPS units from the maker's page
| Product | Type | Capacity | AC outlets | USB / DC ports | Weight | Warranty | Estimated runtime 15 W example load |
|---|---|---|---|---|---|---|---|
| APC Back-UPS Pro BR1500MS2 | UPS | 1500 VA / 900 W | 10 | 2 USB charging ports (Type A + C) | 27.6 lb | 36 months (UPS), 12 months (battery) | Not published |
| APC Back-UPS BE600M1 | UPS | 600 VA / 330 W | 7 | 1 USB charging port | 7.69 lb | 36 months (UPS), 12 months (battery) | Not published |
| APC Back-UPS BE425M | UPS | 425 VA / 255 W | 6 | No USB charging port | 5.7 lb | 36 months (UPS), 12 months (battery) | Not published |
Ordered by stated VA, largest first: a spec order, not a quality ranking. VA is not watts: the watts figure is the one to match against your load. Read .
Prefer a battery that lasts hours? See power stations for a WiFi router, or the full comparison.
How the runtime estimate works
- Hours ≈ battery Wh × 85% ÷ total watts. The 85% is an assumption for power lost in the inverter or converter, not a measured figure.
- The example load of 15 W is 10 W for a router and 5 W for a modem. These are typical examples, not facts about any product.
- Real runtime is shorter when the battery is old or cold, and a UPS or inverter uses some power just by being on.
- Watt-hours = volts × amp-hours. A UPS page that lists only VA gives no runtime; a lead-acid UPS also should not be run to empty.
Sources and quotes
- APC Back-UPS Pro BR1500MS2 · maker's page
- Type:
Product or component type Uninterruptible power supply (UPS)
read 2026-10-19 - Capacity:
Rated power in VA 1500 VA
read 2026-10-19 - Rated output (W):
Rated power in W 900 W
read 2026-10-19 - Battery:
Battery type Lead-Acid battery
read 2026-10-19 - AC outlets:
10x NEMA 5-15R outlets
read 2026-10-19 - USB / DC ports:
2 USB smart charging ports
read 2026-10-19 - Weight (lb):
Product weight 27.6 lb(US) (12.5 kg)
read 2026-10-19 - Warranty:
Warranty (in months) 12 Battery|36 UPS
read 2026-10-19 - APC Back-UPS BE600M1 · maker's page
- Type:
Product or component type Uninterruptible power supply (UPS)
read 2026-10-19 - Capacity:
Rated power in VA 600 VA
read 2026-10-19 - Rated output (W):
Rated power in W 330 W
read 2026-10-19 - Battery:
Battery type Lead-Acid battery
read 2026-10-19 - AC outlets:
7 NEMA outlets (2 surge)
read 2026-10-19 - USB / DC ports:
1 USB smart charging port
read 2026-10-19 - Weight (lb):
Product weight 7.69 lb(US) (3.49 kg)
read 2026-10-19 - Warranty:
Warranty (in months) 36 UPS|12 Battery
read 2026-10-19 - APC Back-UPS BE425M · maker's page
- Type:
Product or component type Uninterruptible power supply (UPS)
read 2026-10-19 - Capacity:
Rated power in VA 425 VA
read 2026-10-19 - Rated output (W):
Rated power in W 255 W
read 2026-10-19 - Battery:
Battery type Lead-Acid battery
read 2026-10-19 - AC outlets:
6 NEMA outlets (2 surge)
read 2026-10-19 - USB / DC ports:
Type of USB power supply None
read 2026-10-19 - Weight (lb):
Product weight 5.7 lb(US) (2.6 kg)
read 2026-10-19 - Warranty:
Warranty (in months) 36 UPS|12 Battery
read 2026-10-19
How we check
- A product is listed only when its type and capacity, and most of its outlets, ports, weight and warranty, each have a quote that appears word for word on the maker's own page, read within the last 30 days.
- Anything the page does not state shows "Not published". Nothing is filled from memory.
- No prices are shown. Pages we could not read, such as CyberPower and Tripp Lite, and the Anker SOLIX C300 DC (its page lacks weight, outlets and warranty), are left out rather than guessed.
- No mini DC UPS (12 V, for routers and ONTs) is listed yet: none had a maker's spec page we could verify.