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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  • mode_13h - Friday, April 22, 2022 - link

    > Sadly, humanity is full of falsehoods for ‘profit’.

    Why is everything bad somehow an indictment of capitalism, yet you never credit it with anything good that's achieved or made accessible to consumers?
  • Oxford Guy - Thursday, May 12, 2022 - link

    Too bad.
  • mode_13h - Wednesday, July 13, 2022 - link

    You have yet to give one modern example representing a viable alternative. Every modern attempt at true socialism thus far has failed. On the other hand, there are examples of regulated capitalism that continue to work well to this day.
  • RU482 - Monday, April 18, 2022 - link

    tangential topic - generators. It seems inverter generators are raved about as being superior, but no one ever seems to mention whether they have a true sine wave output or a modified sine wave output
  • myself248 - Wednesday, April 20, 2022 - link

    > the circuitry layout is fairly outdated.

    A flippant statement like that implies a fairly substantial amount of reverse-engineering that must've gone into such a conclusion! And it would be more persuasive if the intermediate steps were shared -- how was the reverse-engineering performed? What topology does the unit use? What's outdated about it? How does it compare to others on the market?

    I think the UPS market very much needs technically-competent reviews, and this is an encouraging step in that direction. But it could stand to add some rigor and detail. Thank you for the promising start!
  • Leone018 - Wednesday, April 20, 2022 - link

    Is equal to Tripplite ECO1500LCD
  • nikitas589 - Thursday, April 21, 2022 - link

    Nice work - an nice new section - keep them UPSs reviews coming.
    Speaking form experience, line-interactive UPSs may sometimes not respond consistently to power interruptions. I've had one (MGE Eclipse) that for example you would pull the plug and it would work as expected. But for minor power interrupts it wouldn't... so maybe its a nice idea to devise a few power-off scenarios just to make sure the UPS works as expected in a range of scenarios. It wasn't clear tom me in the review if already do so.
  • nikitas589 - Thursday, April 21, 2022 - link

    Oh and the noise level report is 'critical' for home users at least. :-) The quietest I've found on spec is an NJOY's Echo Pro (Online UPS).
  • JFish222 - Thursday, April 21, 2022 - link

    Another +1 for these types of reviews, and additional suggestions:

    1. What is the UPS power draw from the wall when not charging/under load (as mentioned by others).

    2. What status monitoring / remote shutdown capabilities are present.
    In addition to running the local "Powerchute Personal Edition" type software connected via USB, are there remote shut down agents when connecting multiple devices? Are there fleet management capabilities if I have one under every desk, etc.

    3. Low voltage protection (also alluded to, was another interesting question). IE: In the event of an outage, does the battery run to 0% (not grate for Lead Acid), or is there an x% cut-off to protect the battery

    4. Parasitic draw when the unit is powered off.
    Can I keep the unit offline (ie: not in production) but with batteries internally connected without damaging the batteries? There is a natural discharge rate for lead-acid, but if there is parasitic draw even when off, those batteries could be toast when I pull the unit from the cabinet.

    5. Do the USB ports function when the UPS (inverter) is powered down.
    It's an edge case, but not always well identified in specs. In the event of a hurricane/wildfire/[insert longer-term-outage] occurs, this can be a lifesaver. This also may have some IoT applications.

    To those wondering about adding more sockets . . .
    For those wondering what to do if you lack enough power ports on the UPS, I install passive mini extension cords.
    The "squid" style ( https://www.amazon.com/dp/B075ZRB14L) and mini-extension (https://www.amazon.com/dp/B09TC7ZPCJ/) are my go-to's. To address potential criticism of this approach, I always use grounded, passive cords and keep the loads in line with the UPS specs. We work with what we've got!
  • GeoffreyA - Sunday, April 24, 2022 - link

    I don't own one, but UPSes could save the backsides of many in my country, where there are scheduled power cuts all the time, and that we can't always keep track of. Euphemistically called "load shedding," it is sometimes a daily occurrence.

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