A UPS keeps only the equipment plugged into its battery-backed outlets running, and only for as long as its battery and the connected load allow. For most home setups, that means a PC can stay on long enough to save work and shut down cleanly while lights, appliances, and anything outside your home stay dark. A battery-backed router helps only as a dependency, not a guarantee: whether your internet service works during a local outage depends on equipment and networks outside your home that a UPS cannot reach.
What a UPS actually keeps running
A UPS is local backup power for the devices connected to it. It does not back up your house, and it does not restore utility service. Its protection is limited to the outlets wired to the battery.
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- Battery-backed outlets keep the connected device powered from the battery when utility power drops. Runtime is drawn from the battery.
- Surge-only outlets protect against voltage spikes but give no battery time during an outage. Check the back of your unit; labeling varies by model.
Connect only the equipment you need to keep running, and put it on battery-backed outlets. Anything on surge-only outlets goes dark with the rest of the house.
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Sizing a UPS for the outcome you need
Start with what you want to happen when the power fails. The answer determines how much capacity you need.
#1 Best Overall
- 425VA/260W Standby Uninterruptible Power Supply (UPS): Uses simulated sine wave output to provide battery backup power and to safeguard home office, home entertainment including computers, gaming consoles, and broadband routers
- 8 NEMA 5-15R OUTLETS: Four battery backup & surge protected outlets; Four surge protected outlets; INPUT: NEMA 5-15P right angle, 45 degree offset plug with five foot power cord
- ADDITIONAL FEATURES: LED status light indicates Power-On and Wiring Fault, transformer-spaced outlets
- GREENPOWER UPS HIGH EFFICIENCY DESIGN: Reduces power consumption by utilizing a compact charger and power inverter to create an ultra-efficient backup power system for home and office use
- 3-YEAR WARRANTY – INCLUDING THE BATTERY; 75K USD Connected Equipment Guarantee; UL SAFETY CERTIFIED: Product has been tested in a UL certified lab and listed with UL as meeting or exceeding safety standards
Save work and shut down
A short interruption usually calls for enough time to save files and shut the computer down properly. A modest UPS handles this for a desktop PC and monitor in most cases, provided you check its ratings against the actual load.
Keep a session running
If you want to keep gaming or working through a longer outage, plan for a much heavier draw. A desktop gaming system can use battery quickly. Vendor example runtimes for this scenario are listed in the table below.
Ride out a long outage
A UPS is not a long-duration generator substitute. Battery capacity limits how long any UPS can carry a load, and a VA label alone does not tell you how long that will be.
Use these checks before you buy or plug anything in:
Rank #2
- 1500VA / 900W RELIABLE BACKUP POWER: The highest VA capacity available for home use; delivers short-term battery power to keep essential devices powered during blackouts, surges, and unexpected power interruptions
- TEN PROTECTED OUTLETS: Power your entire setup with 5 battery backup outlets for essential devices, and 5 surge-only outlets for peripherals. Plus built-in coaxial and Ethernet surge protection for added peace of mind
- AUTOMATIC VOLTAGE REGULATION (AVR): Corrects low voltage brownouts (88V+) and surges (+/-13%) without draining battery. Boosts or trims to stable 120V. Extends runtime for blackouts; Active PFC compatible for gaming PCs
- REPLACEABLE BATTERY & ENERGY STAR UPS: User-replaceable battery (APCRBC124, sold separately) for zero-downtime swaps. ENERGY STAR certified for 92%+ efficiency, cutting energy costs vs standard UPS units
- LCD DISPLAY PANEL: Features an intuitive LCD screen that displays real-time status information including battery charge level, estimated runtime, load capacity, and input voltage for easy monitoring of your power protection system
- Add up the maximum wattage of every device you plan to connect, including the monitor, router, and modem.
- Confirm that neither the combined watt nor the VA rating of connected equipment exceeds the UPS rating. APC states this as a rule.
- APC’s UPS buying guide suggests the unit’s watt capacity should generally exceed the attached load by 20–25%. Treat this as APC’s recommendation, not an industry standard.
- Do not use the VA figure as a proxy for runtime. Runtime depends on the battery and the real load.
Runtime: what the vendor examples show
APC publishes example runtimes for its 900 W / 1500 VA Back-UPS Pro Gaming unit. These figures come from APC’s product page, which does not state the battery age, test method, or exact configuration behind each number. Treat them as illustrations, not guarantees for your system.
| Example setup (APC product page) | Example runtime | Notes stated by APC |
|---|---|---|
| Gaming PC with one monitor | 13 minutes | Router and modem included by default |
| Gaming laptop with one monitor | 27 minutes | Router and modem included by default |
| Xbox One X with a 55-inch TV | 21 minutes | Router and modem included by default |
| PS4 Pro with one monitor | 22 minutes | Router and modem included by default |
The gaming laptop result is higher than the gaming PC result because the laptop draws less power. Every additional device you connect shortens the time you get, so a runtime figure only applies to the exact load it was measured on. Measure or calculate your own load before relying on any published number.
Why runtime disappoints
Two causes account for most shortfalls: overload and battery age.
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APC’s Back-UPS troubleshooting guidance says an overload can cause connected equipment to lose power. The fix is to remove nonessential equipment from the unit. If the alarm continues, reduce the load further rather than waiting for the battery to run down.
Rank #3
- 1500VA/1000W PFC Sinewave Uninterruptible Power Supply (UPS): Uses sine wave output to provide battery backup power for Active PFC & conventional power supplies; Safeguards computers, workstations, network devices, and telecom equipment
- 12 NEMA 5-15R OUTLETS: 6 battery backup & surge protected outlets, 6 surge protected outlets; INPUT: NEMA 5-15P right angle, 45 degree offset plug with 5 foot power cord; 2 USB charge ports (1 Type-A, 1 Type-C) quickly charge phones and tablets
- MULTIFUNCTION, COLOR LCD PANEL: Displays immediate, detailed information on battery and power conditions; Color display alerts users to potential issues before they can affect critical equipment and cause downtime; Screen tilts up to 22 degrees
- AUTOMATIC VOLTAGE REGULATION (AVR): Corrects minor power fluctuations without switching to battery power; UL SAFETY CERTIFIED: Product has been tested in a UL certified lab and listed with UL as meeting or exceeding safety standards
- 3-YEAR WARRANTY – INCLUDING THE BATTERY; $500,000 Connected Equipment Guarantee; FREE PowerPanel Management Software (Download)
An aging battery
Batteries lose capacity over time. APC’s guidance says an aging battery loses runtime capability. When runtime is inadequate, charge the unit fully, then follow the battery replacement instructions for your specific model. Do not substitute a generic battery without confirming it matches your UPS model.
What to do when the power fails
Do not wait for a low-battery alarm. Use the time you have while the battery is still strong.
- Note the time the outage began so you know how long the battery has been carrying the load.
- Save open documents and close applications that hold unsaved work.
- Shut the computer down using your operating system’s normal shutdown command rather than pulling the plug.
- Leave the UPS running only as long as it needs to keep the equipment you want powered, and let it shut down or power off when the battery is nearly depleted.
APC’s Back-UPS troubleshooting guidance states the instruction directly: “Save all open files, and shutdown the computer.” It appears in that product series’ battery-operation guidance.
Indicator lights differ by model. APC’s FAQ for the Back-UPS series it covers says a rapid green flash means roughly two minutes of runtime remain. Check your own model’s manual before assuming the same meaning on another unit.
Rank #4
- 12 NEMA 5-15R OUTLETS: Six battery backup & surge protected outlets; Six surge protected outlets (Three ECO controlled); INPUT: NEMA 5-15P right angle, 45 degree offset plug with five foot power cord
- MULTIFUNCTION LCD PANEL: Displays immediate, detailed information on battery and power conditions
- ECO MODE: When the UPS detects a computer is off or in sleep mode, it will automatically turn off power to computer peripherals connected to ECO mode outlets, reducing power usage and lowering energy costs
- 3-YEAR WARRANTY – INCLUDING THE BATTERY; $100,000 Connected Equipment Guarantee and FREE PowerPanel Personal Edition Management Software (Download)
Power supply compatibility
APC describes pure sine-wave output as offering the highest degree of compatibility with active power factor correction (PFC) power supplies, which are common in modern PCs. Its troubleshooting guidance also notes that a step-approximated sine waveform may not be accepted by some connected equipment. Check your PC’s power supply documentation and your UPS’s output specification together, since the waveform is a property of the specific model.
Unattended shutdown software
If you leave a PC unattended, a UPS can trigger a controlled shutdown only if the software is installed and supported. APC says its PowerChute Serial Shutdown software can start a graceful shutdown during a prolonged disturbance, but only for the UPS product families the software lists. APC also states that Mac OS is not supported for PowerChute Serial Shutdown. macOS offers its own energy management and scheduled shutdown features, which you can use instead. Verify the UPS model and operating system before counting on automatic shutdown.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Your internet connection is a separate dependency
Plugging a router and modem into a battery-backed outlet keeps those devices powered locally. It does not confirm that your internet service will work during the outage. Your provider’s equipment, the local cable or fiber node, and any cellular or neighborhood infrastructure sit outside your home. APC’s guidance does not establish whether any specific internet provider or neighborhood network stays powered during an outage, so check with your provider about its own backup arrangements.
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Best Value
- 1500VA/900W Intelligent LCD Uninterruptible Power Supply (UPS): Uses simulated sine wave technology to provide battery backup power to safeguard workstations, networking devices, and home entertainment equipment
- 12 NEMA 5-15R OUTLETS: Six battery backup & surge protected outlets; six surge protected outlets; INPUT: NEMA 5-15P plug with 6-foot power cord; USB charge ports (1 Type-A, 1 Type-C) quickly charge mobile phones and tablets
- MULTIFUNCTION, COLOR LCD PANEL: Displays immediate, detailed information on battery and power conditions; Color display alerts users to potential issues before they can affect critical equipment and cause downtime
- AUTOMATIC VOLTAGE REGULATION (AVR): Corrects minor power fluctuations without switching to battery power; UL SAFETY CERTIFIED: Product has been tested in a UL certified lab and listed with UL as meeting or exceeding safety standards
- 3-YEAR WARRANTY – INCLUDING THE BATTERY; 500,000 Connected Equipment Guarantee; FREE PowerPanel Personal Software (Download)
- The modem and router are on battery-backed outlets, not surge-only outlets.
- Their combined draw is included in the UPS sizing calculation.
- You know whether your provider’s equipment has its own backup power.
Where a generator fits
A UPS and a generator solve different problems. Eaton’s handbook states that a generator does not protect equipment from power problems. It describes the UPS as the device that bridges the time until a generator starts and stabilizes its output. A UPS is therefore useful alongside a generator, but a generator is not a reason to skip sizing a UPS. Whether a generator is appropriate for a particular home is outside what this guidance can settle.
Comparing UPS options
If you are choosing between units, compare them on these six points, in this order:
- Usable watt capacity and VA rating, both checked against your combined load.
- Estimated runtime at your measured load, not the vendor example.
- The number and type of battery-backed versus surge-only outlets.
- Output waveform and compatibility with your PC’s power supply.
- Whether the battery is replaceable and whether a model-specific replacement is available.
- Shutdown software and operating-system support.
Keep the router and modem in the calculation if you want internet access to survive a short outage, and remember that the connection still depends on factors outside the UPS.
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