[REVIEW] Viomi S9 is one of the best Chinese vacuum cleaners, and it can empty itself

If you’ve been following trends in the robotic vacuum space, or browsing our site, you’ve surely noticed a new feature from the past few months – an automatic dustbin emptying system in the vacuum. One of these vacuums found its way to our editorial office – VIOMI S9.

We tested not only the automatic emptying, but also put it through our vacuuming and mopping quality test. You can read our impressions in the detailed review. From the VIOMI brand, we’ve already tested the VIOMI SE robotic vacuum, with which we were very satisfied—so our expectations are high.

Where to buy VIOMI S9?

The VIOMI S9 robotic vacuum is currently available from several sellers such as Banggood, Geekbuying, AliExpress, and DHGate. The great part is that at all of these sellers it’s available in European warehouses, so delivery will be exceptionally fast. At the same time, you don’t need to worry about any customs duties or VAT.

Basic specs and features

Probably the biggest draw of this vacuum is the advanced Dumping 2.0 system, thanks to which it automatically empties its dirt container. The charging dock includes a disposable dust bag with a 3 L capacity and a 381 mm-long tube that moves all dirt from the vacuum into the waste bag.

Thanks to the short tube with just one joint, emptying is fast and hassle-free. Other systems use a much longer tube with multiple joints that connects to the vacuum from underneath. This system is slower and less efficient.

Its suction power is 2700 Pa, handled by an advanced and quiet brushless motor that impresses with excellent longevity. The vacuum can also automatically detect when it’s on a carpet, when it increases the pressure.

You also get a quality HEPA filter and a 5200 mAh battery that lasts for approximately 3.6 hours of operation. That means it can clean up to 320 m². Of course, the VIOMI S9 can also wash your floors, with a 250 ml water tank.

There are 3 suction levels and also 3 floor-washing levels. A great feature is that the vacuum can remember maps of multiple rooms and even several floors. That makes it useful not only for small apartments, but also for large family houses or villas. It can then automatically recognize which room it’s in.

The VIOMI S9 has a 360-degree laser on the top part that handles space scanning. The laser technology is extremely accurate (less than 2% deviation) and fast. In one second, it can scan up to 6 times 360° within a distance of 8 meters. The robot vacuum can also overcome obstacles up to a maximum height of 2 cm.

Another highlight is the sterilizing UV system that kills up to 99.99% of bacteria.

Great bundle with accessories, design, and placement of elements

Because the vacuum has a larger docking station, the packaging dimensions are also bigger. The box measures 41,5 x 41,5 x 43.5 cm and it’s placed inside another protective, cardboard outer box that’s very sturdy and provides excellent protection for the whole package.

Inside, the vacuum is stored in an unusual vertical position. Next to it, you’ll find the docking station, a water tank with a mop, and also a small box with accessories. There’s also a clear user manual in English.

Besides the vacuum, the docking station for automatic emptying, and the mopping mop with a cloth, you’ll also find extra accessories here—something that isn’t very common. Specifically, you get a replacement three-armed brush that collects dirt under the vacuum, 10 pieces of disposable mopping cloth pads, and 3 dust bags that are inserted into the docking station. These extra accessories will be a nice bonus, and we’d be happy to see them included with other vacuums too.

When it comes to the design, we think it’s a real success. We had the vacuum available in an elegant white color with blue accents. It’s also available in black. The LDS 2.0 laser space scanning system is located in the center of the top part, where we also find 2 buttons – power on / off and return to the docking station.

A bumper is placed around the perimeter, which the vacuum uses to detect obstacles by bumping into them, along with several sensors. Unlike the VIOMI SE model, here the dust container is slid in from the back. There’s no openable top, which increases the overall structural strength. The dust container simply slides out from the back and also includes charging connectors as well as an opening for automatically sucking dust into a bag in the docking station.

The bottom part is already the classic one: wheels, a removable rotating brush, a three-spoke swivel brush, and anti-fall sensors. Plus, we also have a very interesting new feature here in the form of an UV sterilization strip, which sits between the rotating brush and the front, small wheel.

Docking station and first power-on

The docking station itself is, for obvious reasons, significantly larger than we’re used to with robotic vacuums, with dimensions of roughly 25 x 19 x 36 cm. On the bottom there’s an opening for suction of dirt from the vacuum and the charging connectors. On the sides, there are air vents, and the front has an LED display that can show the current vacuum battery status and the waste bag status.

The docking station opens from the top, and inside you’ll only find the dust bag, a brief description of how to install it, and a small brush for cleaning the rotating brush from hair and other dirt. The docking station doesn’t turn off—it’s always active as long as it’s connected to power, and during vacuum charging or while it’s running it doesn’t show any data. Those appear only when the vacuum is connected and when it’s emptied.

So the first power-on consists of plugging in the docking station and switching on the vacuum itself using the button on the top. Once turned on, the vacuum is ready to pair with the app, which is also confirmed with clear voice prompts.

Add to Mi Home app

Since the VIOMI brand is part of Xiaomi’s ecosystem, the vacuum can be added to the Xiaomi Home (Mi Home) app. Pairing is very simple and quick—just like with any other product. In the app, the vacuum appeared automatically because your smartphone detected it nearby.

If that doesn’t happen, simply search for the specific model in the list or scan its QR code. Next, we entered the details of our WiFi network, and the vacuum automatically paired with the app. The last step is naming the vacuum and assigning it to a room.

During the first cleaning, a map of the rooms gradually appears in the app. The vacuum first went around the perimeter of the first room, then cleaned it right away using the well-known system, and only afterwards moved on to the next room.

In the same way, it gradually cleaned all the rooms in the apartment. We tested the VIOMI S9 in a three-room apartment. Thresholds higher than 2 cm that it can’t overcome lead into the bathroom and toilet. We also didn’t let it into the wardrobe, so the total area it managed to clean is 37 m². The first cleaning took 43 minutes.

The next cleaning is already faster and takes 37 minutes.

Automatic emptying

After each cleaning, VIOMI S9 automatically connects to the docking station, where the contents of its dust bin are emptied. Everything happens automatically, and the docking station with the waste bag vacuums all the dust from the vacuum. During this process, the noise level rises significantly, but the whole operation takes only a few seconds.

During this operation, the docking station shows on its LED display information about the vacuum’s current battery capacity and also the current status of the trash bag. A detailed fill level of the bag is not available, but the docking station can alert you when it’s time to replace the bag.

After the emptying process is finished, the LED display turns off and no data is shown anymore. We miss a button that would let us display information on this screen, at least for a few seconds.

Our impressions, suction levels, and cleaning quality

The VIOMI S9 robotic vacuum cleans really well, and what’s more, its cleaning speed is quite high. We were also impressed by its quick response to a start command from the app. The vacuum reacts almost immediately after pressing the “Start” button: it disconnects from the docking station right away and heads into the room.

We also like how the elements are laid out in the app. The cleaning mode settings (vacuuming, mopping, or vacuuming with mopping), as well as the suction and mopping levels, are on the home screen right under the current map. At the top, you can see the floor area, the cleaning time, and the remaining battery capacity in percent.

We see a downside in how it discovers obstacles. VIOMI S9 doesn’t have a camera or any sensors that would let it avoid and navigate around obstacles. Instead, it bumps into them, similarly to most robotic vacuums. However, the impacts can be quite strong at times. It didn’t happen that the vacuum tipped something over, but we secured the areas in advance so that it wouldn’t.

Moving around the rooms and the actual vacuuming or mopping is trouble-free. During a few weeks of testing, the vacuum got stuck only once, when it reached a very narrow area from which it couldn’t get out. When vacuuming carpets, you can clearly see a slowdown, and at times the vacuum spent more time than we expected on a carpet with longer fibers.

As usual, we also tested the cleaning quality on the kitchen tiles, where we scattered breadcrumbs mixed with coffee and red lentils. For a better idea, we’re including a photo of the floor before cleaning:

After the first run at the highest level, there were still a few particles left on the floor. The coffee was gone, but the breadcrumbs and lentils couldn’t be completely and perfectly vacuumed up. Even after the second run, the tile floor still wasn’t flawlessly clean—some dirt remained in the grout lines between the tiles.

As for noise levels, we measured them with a digital sound level meter in all modes:

• silent – 56 dB
• standard – 60 dB
• medium – 70 dB
• powerful – 72 dB
• during emptying – 75 dB

Mopping quality

As we mentioned in the introduction, the package includes 10 disposable mop pads and one cloth. We used the cloth. Mopping is available in three levels – level 1 to 3. Since robot vacuums usually don’t impress with mopping quality, we used the highest level.

Again, we spilled onto the kitchen tile floor water diluted with cocoa and food coloring, which we let dry. Then we sent the vacuum to wash the kitchen. You can see a photo of the floor before mopping below:

After the first mopping, the vacuum was able to wash off smaller spots. After the second, almost everything was removed, and after the third mopping the floor was nearly perfectly clean. Only a small spot of food coloring remained. The vacuum mopped in Y mode, so each spot was passed over multiple times, achieving higher mopping efficiency than most other robot vacuum cleaners.

Runtime on a single charge

The manufacturer states that the battery lasts up to 3.6 h on a single charge. However, we couldn’t find under what conditions— and in which mode—this kind of runtime was measured. The vacuum has a 5200 mAh battery and should clean an area of 320 m².

We first tested the runtime at the highest suction power. In that mode, the vacuum managed to move through our apartment nearly 3× (105 m² in total), taking 1 hour and 50 minutes. In Standard mode, it cleaned our apartment nearly 4× (127 m² in total) and took 2 hours and 15 minutes.

Map customization

VIOMI S9 can split the space into individual rooms by itself right after the first cleaning. We liked that each room got its own unique color and number. Other vacuums usually have only a very limited color palette, so multiple rooms end up with the same color.

If you don’t like the automatic room split or you want to make changes, you can use the map management. Here you can change how the map is divided into rooms, rename them, mark virtual walls or no-go zones. You can also choose to clean only the marked area or a single point.

You can merge or split rooms, and you can name them with your own custom names—not only the default ones.

Settings in the Mi Home app

The app settings offer several customization options. Here you’ll find one-time edge cleaning, repeated cleaning, records of past cleanings, and the Do Not Disturb mode. The mopping style option is especially interesting. You can choose between S and Y modes, which represent the vacuum’s path shape. S mode is the classic one that everyone knows. Y mode cleans the space more thoroughly, but it takes a bit longer.

In the settings, you can also choose a map if you have multi-floor premises, or delete the map if needed. There are 3 languages in which the vacuum can speak to you. They are English, Chinese, and German. You can also adjust the volume.

You can also see the status of individual components and accessories (main brush, mop, side brush, and filter), find the vacuum, use remote control, change the vacuum’s name in the app, share the device with other users, enable automation, and access other settings that most robot vacuums offer.

VIOMI S9: Final rating

VIOMI S9 is a high-quality robotic vacuum with automatic emptying of the dust bin. This function is excellent and frees you from the troublesome task of emptying the bin from the vacuum, which often gets messy. Thanks to this system—one that works really well—you just need to periodically throw away the full dust bag from the docking station and insert a new one. The system is especially great for people with dust allergies and for those who want to take their level of automatic cleaning to a new level.

We also appreciate the new UV sterilization feature and the included set of a few disposable mops and trash bags in the base package.

A small downside is the increased noise during automatic dustbin emptying, and the obstacle detection via collisions. Overall though, it’s a very well-executed vacuum with a new technology at a reasonable price.