CyberPower ST425 Standby UPS Battery Backup and Surge Protector, 425VA/260W, 8 Outlets, Compact, UL Certified

I recently purchased the CyberPower ST425 Standby UPS System, and it's exactly what I needed for protecting my electronics. This compact unit offers 425VA/260W of backup power, which is perfect for keeping my essential devices running during short power outages or preventing data loss from unexpected surges. With 8 outlets, I have plenty of space to plug in my computer, monitor, modem, and other peripherals. The compact size is a major plus – it fits neatly under my desk without taking up much space. The black finish is also sleek and blends in well. Setup was incredibly easy; I just plugged it in and connected my devices. It provides peace of mind knowing that my equipment is protected from power fluctuations and that I'll have a few minutes of backup power to save my work and shut down properly during an outage. For anyone looking for an affordable, reliable, and compact UPS to protect their valuable electronics, the CyberPower ST425 is an excellent choice. It's a great value for the features it provides.

Just what I needed for the storms. Working great when the power goes out, on,out on during bad weather.

I use CyberPower UPS's on all of my computers and modems. The batteries last about 5 years and I had to replace one unit in 8 years. They have worked through a number of power failures, and I have used them to recharge cell phones during a power failure. The units give clean power when using a portable generator during a power failure (not a whole house generator).

The CyberPower SL700U is the kind of UPS you keep around not because it’s a powerhouse, but because it’s a polite, dependable little buffer that smooths out life’s electrical hiccups. It’s slim, unobtrusive, and perfect for the gear that really just needs clean, uninterrupted power long enough to avoid a reboot—modems, routers, ONTs, or those tiny-but-critical devices that absolutely should not experience a brownout. As a surge protector plus brief-runtime UPS, it does its job without fanfare or fuss, and that’s exactly what you want in a unit this size. In day-to-day use, the SL700U behaves like a compact shock absorber. Voltage drops? It catches them. Blips and flickers? It shrugs and gives you the extra seconds you need. Full outages? Well… it’ll keep your small gear running for 10–15 minutes, maybe a bit more if the load is tiny—but this is a UPS you choose for coverage, not marathon endurance. It’s not something you’d use for a full networking rack or anything mission-critical. But for protecting your modem during ISP maintenance, or keeping your router alive while your bigger UPS is rebooting, updating, or being swapped? It’s perfect. Its real value shows up when paired with larger systems. If you’ve got a bigger UPS or portable power station as your primary backbone, this little CyberPower becomes the perfect “inline buffer”—absorbing those moments where the big device switches modes, resets a circuit, or needs a firmware update. Instead of a hard network drop, everything downstream keeps humming along as if nothing happened. For anyone who works with layered power systems or wants belt-and-suspenders protection for the gear that holds everything together, the SL700U fits that niche beautifully. It’s not designed to be an all-purpose safety net, but within its intended role it’s wonderfully reliable. Treat it as the “hiccup protector” for sensitive electronics, especially in modest or home office setups, and it will earn its spot. Just don’t ask it to run a switch stack or an office during a blackout—this is the helpful sidekick, not the hero. Pros • Slim, compact, and easy to place behind desks or network shelves • Ideal for modems, routers, ONTs, and other low-draw devices • Smoothly handles flickers and short drops without reboots • Perfect as a buffer behind larger UPS or power systems • UL certified and generally very reliable for its class Cons • Very limited runtime—10–15 minutes max under typical loads • Not suitable for full racks or high-draw equipment • Standby design means it’s not as smooth as line-interactive models • Battery longevity is decent, but not exceptional

The electricity went out very briefly a moment ago. It’s the first chance I’ve had to see if it does work. And it absolutely does. I have a Mac Mini M4, 6 external desktop drives, and a monitor on the UPS side of the device. When the electricity failed, the unit gave a single beep, alerting me and giving me time to turn on the monitor and begin shutting down. Luckily it all came back on before that was necessary. But it would absolutely would have allowed for that much time. It’s affordable and well made by a solid company! I’m going to get a couple more for another cluster of computers.

ST625U received 2-25-2020 - I have not had a power outage yet but they happen a lot here in Florida during tropical storm season. EDIT UPDATE ON 10/19/2020 - IMPRESSIVE PERFORMANCE OF ALL THREE OF MY ST625U UPS units when a massive sustained power surge from an underground power cable failure burnt up 5 of my home's stand alone surge protector outlets! My CPAP kept running right through the event while my neighbor's wall wiring burnt up! All 3 of my 625's are still working after giving 40 minutes of stand-by power and their breakers did not blow - END EDIT .... SECOND EDIT 10/2023: all 3 of my units and their batteries are still going strong! I just slept through a short power outage while using CPAP END SECOND EDIT. A slight odor of 'burnt' electronics right out of the box is normal for some electronics product manufacturing methods, do not be concerned with a slight odor that does not get stronger with use. It will diminish. I tested this unit with my powered 5 motor recliner, an LED desk light and laptop running while it was unplugged from the wall 5 minutes. I will definitely update the review if any issue develops (done!). I'm a degreed biomedical technician and this design looks fine for short term outages. This is NOT for CPAP sleeping use, battery is far too small except for short power outages. The isolated battery compartment opens easily with one phillips screw and only has battery wires inside it. I inspected the battery and found 13.2 volt charge after 6 hours plugged in. The charging circuit is extra energy efficient and causes almost no detectable waste heat, an excellent feature, as claimed on the box. After 6 hours there was only one small area of the case that had a barely warm feeling, like human skin. You can triple the run time when the original battery wears out by adding a larger battery that does not fit in the case, like a 17 AH SLA battery. You have to extend the battery wires long enough to let the battery sit next to the UPS. You must have soldering skills and the right tools to do this. The larger battery will not allow use of larger, more power hungry devices but it will greatly increase run time for your existing use during power outages. The larger batteries cost about the same but they are more durable. I have no interest in setting up the software monitoring. Just a gimmick for this size device. The UPS software may not recognize a larger battery capacity but it might if it is based only on voltage remaining. As the instructions say, this will beep when power goes out but you can mute the beeping in advance by tapping the main power button twice. I don't know if it retains the mute setting after a complete battery discharge. You can just locate a battery the same dimensions of the original if you want it to fit in the case. It is 'CPS5.5AH' 6 inches long, 3 3/4 high without terminals, and 2 inches wide. I decided to buy another one of this model for my modem, router and Ooma phone box to prevent those tedious full reboots after a power glitch.

have had this a couple of months and its doing the job like it should. just plug and play, so easy installation. no complaints on the design. I like that one side of the plugs are battery back up but the other side is just surge protection so you have options

Great devices, normally. I have 3 of these, with 2 in service, 1 yet to be setup. The backup was only used for a few minutes over the last ~3 years since I purchased it, generally able to run uninterrupted for a couple minutes when power went off/on in a matter of seconds, maybe minutes. I only have 1 semi-large draw item plugged into the battery side, with the 2 smaller items being a tiny router and fiber jack. I expect during a true outage the battery backup to last ~10-15 minutes top, but when I finally experienced a true outage (lasted about 10 minutes), the battery lasted only a few seconds. Really bummed me out that after ~2 years, it failed when I needed it most. The ST625U I have still seems to be chugging along just fine. My other ST425 (purchased 2 years ago) is powering my desktop PC and I plan to upgrade it to a ST900U for a more power appropriate backup, but even when running the ST425 for the desktop, it alarmed but lasted way longer than the one powering the below devices, which leads me to believe the battery in the ST425 that failed me is junk. Connected Devices NVR system > 52V @ 2.88A → ~150W 12V router > 12V @ 0.5A → ~6W Google Fiber Jack (GFLT110) > let's say ~4W draw Total Combined Load ≈ 160 watts Expected Runtime on ST425 ~15 minutes of backup power under continuous load. Actual runtime = almost instant death, likely poor quality battery.