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CyberPower ST425 UPS: unboxing, setup and what it can really power
Short answer: the CyberPower ST425 is a tiny, budget UPS (425 VA / 260 W, about $60) that is fine for small loads like a Mac mini, a cable modem or a network switch. For a regular desktop computer I recommend a bigger unit, around 1,000 W, because this one may only run it for a minute or two, or not at all.
What you get: the specs on the box
- Capacity: 425 VA / 260 W.
- Outlets: 8 surge-protected outlets; 4 of them also have battery backup.
- Surge protection: close to 900 joules, plus a $75,000 connected-equipment guarantee (if something is damaged because the UPS did not protect it, you deal with the company).
- Input: 96–140 V, 50/60 Hz; output 120 V simulated sine wave (not pure sine wave like the better inverters).
- Weight: about 4 lb (under 2 kg); cord around 5 ft; made in the Philippines.
Step 1: plug in the right devices
One side of the unit is labeled surge protected outlets with battery; the other side is surge protection only. Put the computer (or modem/switch) on the battery side. Use the surge-only side for things that don't need to stay on during an outage, like a monitor or an inkjet printer.
Step 2: connect to a grounded outlet and charge
The label says the UPS must be connected to a grounded outlet before you turn it on, and you should charge it for 8 hours. After that you don't have to configure anything: plug it in and it works. Press and hold the power button for 2 seconds to turn it on (and the same to turn it off). When you unplug it from the wall it keeps running and starts beeping.
Step 3: write down the date and label the outlets
A tip I use on every UPS: write the purchase date on the unit and, if you can, on the battery. Years later you'll know when the battery is due for replacement. I also mark the battery side (for example “BAT”) so I always know which outlets are backed up.
How long will it run?
The battery inside is very small (about 2.9 Ah, smaller than a phone and similar to a small Ryobi tool battery). In my experience a Mac mini with an Intel i7 may last about 10 minutes, while a Mac mini with an M2 or newer chip can last around 40 minutes. That's why I bought it: for my Mac mini. For a modem, router or switch it is also a good fit.
Limitations: no USB or network port
This model has no USB or RJ45 port and no software. Better UPS units (I like APC) can connect to your computer or network, put the computer into standby automatically when the power goes out, and log outages and power fluctuations. With the ST425 the equipment simply runs until the battery is empty. For about $60 it's the most economical option: enough if you want something basic, but get a bigger, managed unit for anything more important.
Who should buy the ST425?
Buy it if you want to protect small, low-power equipment from short power blinks, brownouts and surges: a Mac mini, a cable modem, a router or a network switch. It is compact, light and cheap, and the four battery outlets cover a typical home network. It keeps your internet up for a few minutes so you don't lose your work when the power blinks.
Skip it if you need to power a regular desktop PC, want automatic shutdown, or want to see a log of outages and power fluctuations. In that case look for a unit around 1,000 W with a USB or RJ45 port and software.
Frequently asked questions
Can the CyberPower ST425 run a desktop PC?
Not recommended. It is 425 VA / 260 W; for a regular computer I recommend a unit around 1,000 W, otherwise it may last only a minute or two or not work at all.
How long does it keep a Mac mini on?
In my experience about 10 minutes for an Intel i7 Mac mini and around 40 minutes for an M2 or newer Mac mini.
Do I need to configure it?
No. Connect it to a grounded outlet, charge it for 8 hours, and press the power button for 2 seconds. It has no software or USB port.
Is the output pure sine wave?
No. The label says 120 V simulated sine wave.