Skip to main content
CyberPower ST425 Standby UPS Battery Backup and Surge Protector
CyberPower

CyberPower ST425 Standby UPS Battery Backup and Surge Protector

Bottom line: The CyberPower ST425 Standby UPS Battery Backup and Surge Protector ($59.95 on Amazon as of 2026-10-20 16:14 UTC): 8 outlets split 4 battery-backup+surge and 4 surge-only; main trade-off: simulated sine wave, not pure sine, so some active PFC PSUs may object.

$59.95

As an Amazon Associate, SpecPicks earns from qualifying purchases. Full disclosure →

Buy on Amazon — $59.95 Also on eBay → Compare to similar power protection

By , Founder & Editor-in-Chief · Listing data updated

Mike Perry — Hardware researcher since 2014. For retro PC hardware and period-correct parts, synthesises manufacturer documentation, community compatibility lists and marketplace listings rather than first-hand lab testing. Core beat: GPU performance across gaming, rendering, and local-LLM inference.

*Price sourced from Amazon.com. Last updated 2026-10-20. Price and availability subject to change.

Pros & Cons

Pros

  • ✓ 8 outlets split 4 battery-backup+surge and 4 surge-only
  • ✓ 3-year warranty that covers the battery itself, not just the unit
  • ✓ 75,000 USD connected equipment guarantee, UL certified lab tested
  • ✓ Transformer-spaced outlets fit bulky wall-wart adapters

Cons

  • ✗ Simulated sine wave, not pure sine, so some active PFC PSUs may object
  • ✗ 260W ceiling rules out gaming desktops with discrete GPUs
  • ✗ Only 4 of the 8 outlets get battery backup
  • ✗ Single LED reports status; no LCD load or runtime readout

Manufacturer description

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

Related Products

Other products in this category you may like:

SpecPicks Verdict

SpecPicks scored CyberPower ST425 Standby UPS Battery Backup and Surge Protector using a rating × review-volume × price-fit model applied to published specs and reviews across the power protection category. CyberPower's power protection lineup sits within the broader category mid-tier; price and specs are the deciding factors over brand loyalty here. Judge it on the specification table and the price rather than on sentiment: check the figures that decide your use case, then put it side-by-side with two or three close alternatives in the Compare tool before clicking through.

Common buyer scenarios for power protection of this kind: matching it to an existing build, replacing a failing part, or upgrading from a previous-generation equivalent. Check the spec table below against your current setup — particularly socket / form-factor / power-rating fields — and confirm compatibility on the retailer's listing before purchase. Prices and stock are set by the retailer and may have moved since this page was last updated.

Frequently Asked Questions

How much runtime does the ST425 give during an outage?

CyberPower rates it for enough backup to ride out a brief outage and perform a graceful shutdown, not extended operation. Actual minutes depend on how close your load sits to the 260W ceiling. Check the product listing for the manufacturer's runtime chart.

Can it run a gaming PC?

Only a low-draw one. The 425VA/260W rating covers a small desktop, monitor, router, or console. A gaming desktop with a discrete GPU will exceed 260W under load and trip the overload.

Do all 8 outlets have battery backup?

No. Four NEMA 5-15R outlets are battery backup plus surge protected, and four are surge protected only. Put your PC and router on the backup bank and printers or speakers on the surge-only bank.

Is the battery replaceable and what does the warranty cover?

The 3-year warranty explicitly includes the battery, and the unit carries a 75,000 USD connected equipment guarantee. Check the product listing for CyberPower's current replacement battery part number and terms.

Will simulated sine wave output work with my power supply?

The ST425 outputs simulated sine wave, which most standard PSUs, routers, and consoles handle. Some active PFC power supplies are sensitive to stepped waveforms; verify your PSU's compatibility before relying on it for backup.

Key Features

  • 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

Full Specifications

Size425VA
BrandCyberPower
ColorBlack
ModelST425
Warranty3-YEAR WARRANTY – INCLUDING THE BATTERY, $75,000 Connected Equipment Guarantee
UnitCount1
ReleaseDate2018-08-10T00:00:01Z
ManufacturerCyber Power Systems (USA), Inc.
ItemPartNumberST425

Ready to buy?

CyberPower ST425 Standby UPS Battery Backup and Surge Protector is listed on Amazon. Price, availability, shipping and returns are set by Amazon and its sellers — check the listing for current terms. SpecPicks earns a small commission on qualifying purchases — thank you for supporting independent review work.

Buy on Amazon — $59.95

*Price sourced from Amazon.com. Last updated 2026-10-20. Price and availability subject to change.

Related Power Protection

Keep exploring SpecPicks

Other buying guides

Browse the catalog

Editorial

More guides & deep dives from the SpecPicks archive

Browse all articles & guides →

More reviews from the SpecPicks archive

Browse all reviews →

Earliest SpecPicks reviews

Browse full archive →
CyberPower ST425 Standby UPS Battery Backup and Surge Protector
$59.95
View on Amazon →