Editor's Note: Today we're kicking off a new review category for AnandTech: Uninterruptible Power Supplies. These devices are becoming increasingly common as desktop users are looking for laptop-like reliability. All the while, it's also an area that we feel is lacking in good, EE-enlightened systematic reviews. So our multi-talented power guru, E. Fylladitakis, is applying his skills to UPSes. As this is a new area for us, please let us know what you think in the comments below!

While Uninterruptible Power Supplies are hardly a new thing in the PC space, the tried-and-true battery backups for desktop PCs have been undergoing a resurgence in popularity in recent years. Improvements in power delivery technology such as GaNs have been reducing costs and improving reliability, and meanwhile lithium-ion batteries, with their much greater energy density/lower volume, are starting to make inroads on the UPS market as well. All the while, with laptops outselling desktops in the consumer PC market, a PC that doesn't shut itself down during a power outage is becoming the norm, rather than the exception. So what better time is there to take a look at UPSes?

To kick off our inaugural UPS review, we're starting with a 1500VA unit from BlueWalker. BlueWalker is a company that originates from Germany and specializes on the design and marketing of power-related equipment. The company was founded in 2004, making it one of the oldest household UPS/AVR manufacturers that still exist to this date.

BlueWalker is marketing their retail products under the PowerWalker brand name and has a very wide portfolio of both hardware and software products available. For today’s review, we are taking a look at the PowerWalker VI 1500 CSW, a 1500VA/900W UPS that boasts a true sinewave output.

PowerWalker VI 1500 CSW
Power Capacity 1500VA/900W
Output Voltage 230 VAC
Input Voltage 170-280 VAC
Type Line Interactive
True Sinewave Yes (ish)
Battery Lead-Acid, 2x 12V/9Ah
Full Load Backup Time 3.5min
Half Load Backup Time 10min
Battery-Backed Sockets 2 (Type F)
Surge Protected Sockets 2 (Type F)
USB-A Outputs 2 (2.1A)
Ethernet Surge Protection Yes
LCD Display Yes
Dimensions 99 x 280 x 410 mm
Weight 13.1 kg

Given that BlueWalker is a German company, there should be little surprise that the PowerWalker VI is geared towards the European market. The UPS only outputs at a nominal 230V, and similarly, is only designed to accept voltages around that range (sorry, Americans!). Past that, this specific version comes with 2 battery-backed Type F sockets, as well as another two sockets with just surge protection. With 216 Wh of lead-acid battery capacity, it's rated to run a full load for a few minutes, stretching into the double-digits at a half load or less.

Of particular interest with this UPS is the price: true sinewave units have historically carried a significant price premium, but BlueWalker isn't charging nearly the same premium as true sinewave UPSes from other major manufacturers, making the PowerWalker VI 1500 CSW a much cheaper UPS – and at around 180, one that's popular on the market as a result. But can it live up to the same high power delivery expectations without the same wallet-busting price? Let's find out.

The PowerWalker VI 1500 CSW UPS

We received the PowerWalker VI 1500 CSW in a relatively simple cardboard box, with the heavy unit well-protected by thick packaging foam pieces. Inside the box, we found a CD with the compatible monitoring software, thorough manuals in several languages, and a USB cable.


The PowerWalker VI 1500 CSW is a tower-style UPS with an LCD screen at the front. Measuring only 410 mm deep, 100 mm wide, and 280 mm tall (16.2 in × 4 in × 11 in), it is very compact for a unit with that high of an output. There are also two USB charging ports at the front, right under the LCD screen.


The LCD screen, once turned on, will show the basic electrical figures of the unit, such as the voltage, the load, and the remaining battery time. It stays off most of the time and the user needs to press the power button momentarily in order to turn it on.

At the rear side of the tower, we find four power sockets. We are testing the version with the four Schuko (Type F) sockets, but BlueWalker also offers this unit with UK and FR sockets, plus a version with eight IEC socket.

Note that only two sockets offer battery backup, as the other two are for surge protection only. In fact, having just two sockets connected to the unit’s battery backup output is an atypically low number of powered sockets for a 1500VA UPS, as we usually see more.

Along with power protection, there is also a non-destructive circuit breaker and an Ethernet surge protection path (input-output jacks) available with the PowerWalker. Finally, there is a fan that will only turn on when the unit is running on batteries, charging its batteries, or in auto voltage regulation (AVR) mode. The AVR mode essentially has the unit running on grid power but forces the AVR circuit to operate, which may be useful in some situations where the power grid is energized, but very unreliable.


More than half of the front fascia is a door that must be removed in order to access the battery compartment. It is held in place by two small screws at the bottom side of the unit. Once removed, a very large connector can be seen that connects the batteries to the main unit. This needs to be unplugged in order to remove the batteries. If the batteries need to be replaced, the wiring must be unplugged and transferred to the new batteries. We found two Leoch 12V 9Ah batteries in the unit, connected in series (24V 9Ah output). Leoch is a Chinese manufacturer of batteries that is amongst the largest on the planet and whose products are considered to be of fairly good quality.

Cracking open the unit’s body, we can see the unit’s large transformer and circuitry. The transformer actually is not very large for the 1500 VA unit and the amount of cooling it receives from the fan is fairly low. This will not be a problem for the stock unit, where the batteries will likely last just a few minutes, as there will not be enough time for the transformer to overheat. Modifying the unit’s batteries to increase its autonomy in any way without greatly upgrading its cooling capabilities would be, however, nothing short of suicidal.


The power circuitry left us with mixed feelings. The relays are supplied by Golden Relays, a reputable manufacturer, yet the capacitors are supplied by Aishi and Jamicon, suppliers that are considered to be mediocre. Eight IRF3205 MOSFETs generate the output when the unit switches to its batteries, MOSFETs that are proven to be reliable but, having been released well over two decades ago, are nowadays very cheap and their performance is relatively poor compared to more modern MOSFETs. The workmanship is very good but the circuitry layout is fairly outdated.

Testing Results & Conclusion
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  • sor - Wednesday, April 13, 2022 - link

    I'm probably in the minority, but I have an 8 hour whole house battery backup. The UPS is here at my desk to gap the moments it takes for that to kick in.

    That said, I've got two computers, my network gear, and a 38" monitor plugged into a small-ish Back-UPS Pro 1000S and the load currently says 72W with an estimated backup time of 53 minutes.

    Also, the majority of power outages in my area (maybe once a year) last less than a minute.
  • Mikewind Dale - Wednesday, April 13, 2022 - link

    A friend of mine has a gas generator that takes a few seconds to kick in, so I told him to buy a Cyberpower CP1500PFCLCD PFC Sinewave UPS for his ThreadRipper Pro 3955WX. And it works.
  • t.s - Thursday, April 14, 2022 - link

    Very nice electricity there. Here, at least in a month (average), there's 1 time power outages and usually goes for 2 hours.
  • Thunder 57 - Friday, April 15, 2022 - link

    Not sure where you are from but I took a battery just the other day to Home Depot. There was a bin just for batteries you could toss them in. There are other places that do that too. And yes, a UPS on a modem/router is very nice to have. Keeps your internet up and you can use a tablet/laptop for plenty of time.
  • Lezmaka - Wednesday, April 13, 2022 - link

    I'm just one person (physically, mentally... that's still undetermined) but I liked this. With more people (like me) working from home hopefully there's enough interest to see more of these. I'd personally like a little more educational commentary, either as part of reviews or guides, but hope to see more of these.
  • jamesindevon - Wednesday, April 13, 2022 - link

    Great review - thanks. It could have done with a mention of the USB socket around the back -- it should be there so attached PCs can power down safely when the unit goes to battery power. A few words on this and any provided software would have been good (can one PC send a shutdown signal to another?)

    Also, you might want to mention that European grid frequencies vary a lot more than this unit.
  • romrunning - Wednesday, April 13, 2022 - link

    I am interested in seeing some APC reviews, especially at 1k+. APC (Scheider Electric) still seems to be the market leader in North America, so would love to see their products reviewed. My favorite does seem to be the 1500VA spot, so I'm curious to see whether the savings on the cheaper CyberPower is worth it.
  • tyger11 - Wednesday, April 13, 2022 - link

    I went with CyberPower units after an APC one died on me, and I've never looked back,
  • domih - Wednesday, April 13, 2022 - link

    Same here. I've a few APC ones which I bought when CompUSA (brick and mortar) died and was selling them at a quarter of the price by the last week. Otherwise I have many more CyberPower. No problems with both brands. Both brands did their job several several time during power outages. Meaning: the power went down for a few seconds and the computers did not mind. Or the power was out for hours and I had time to do normal shutdowns (automatic or manual). Contrary to APC, the CyberPower Windows Server software app was free. I don't really care anymore because I switched to Linux years ago. I also got several additional APC and CyberPower for free from a company that did not want them anymore and was on the verge to e-waste them. Like my first generation of UPSes I just replace the batteries and they were like new. All the models I have from both brands use the same battery anyway: any equivalent to DURACELL DURA12-8F2 12v 8Ah AGM. I went to a local brick and mortar battery retailer. He smiled and gave me a good discount when I ask the price for 24 units :-)
  • mode_13h - Wednesday, April 13, 2022 - link

    I had a Cyber Power CP685AVRLCD fail pretty badly on me, after about 5-6 years of use. I seem to recall it emitted a strange noise and started emitting a funny odor, not prompted by any sort of power event that I could discern. I can't remember if it also cut power to the outlets, but I think so.

    We've had a couple APC units fail, at work. The most common thing I see is that a unit appears completely bricked, but the issue is that its battery is simply too dead. As a result, it gives no signs of life when plugged in. After installing a fresh battery, they seem to return to fully working status. However, I'm not counting that as "failed" - I just mention it as a caution to anyone who thinks they need to dump an old UPS that *seems* dead, after not being plugged in for a long time.

    Keep your UPS's plugged into A/C, even if you're not using them! Lead acid batteries DO NOT like deep discharges!

    Anyway, we have some APC rack mount units are probably 20 years old and still kicking. They're not on anything mission-critical, so as long as they don't catch fire or something, there seems to be no need to replace them.

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