The Viomi Alpha S9 robovac self-empties its dustbin into the docking/charge station and has a clip-on robomop/sweeper plate. A good package all around and currently on special for $599 (usually $999).
Now, the extra self-emptying functionality – taking a dump – is nice. But it raises the issue – would you rather have the best robomop and robovac and manually empty its dustbin or a typical robovac/mop and occasionally empty the docking bin (don’t worry – it uses a 3L disposable bag)? Let me tell you the answer.
Faced with the fact that the self-emptying dock adds to the price, I would rather spend more on a better mop/vacuum and forget the dock. Let me reassure you that the Viomi Alpha S9 is quite a good robovac/mop – but it is no better or worse than its lower cost siblings, the V2 Pro and V3.
The Viomi Alpha S9 ticks all the boxes for a typical robovac/mop but, to a discerning buyer, there are better robovacs and robomops – they just don’t exist in the one device yet.
Read the Guide first!
We put a lot of effort into our robovac and robomop guide because a) anyone wanting to buy one should read it first to clarify what cleaning robots can and can’t do, and b) we needed a consistent set of paradigms to test and review against.
Our opening statement is as accurate as ever, “It is fair to say that technically, none have met our expectations. Perhaps those expectations are too high.”
We have found and have no fear of contradiction that a combo robovac/mop is not as good as the best robovac and separate robomop.
The two separate ones to beat are the Gen 4 Dreame L10 Pro Gen 3 3D Dual-Lidar robovac (9.3/10) and the Hobot Legee 7 robomop (9.1/10).
Let’s see how the Viomi stacks up. We are trying a new condensed review format to save you reading so many words.
Viomi Alpha S9 self-emptying robot
Global Website | Here |
PC Byte store | Here |
Manual (PDF check downloads) | Here |
Price | RRP $999 on sale at review time $549 |
Country of Manufacture | China |
Company | A Chinese public company. Xiaomi is its strategic partner and major shareholder, and Viomi is part of its ‘mi HOME ecosystem’. Viomi has developed an ecosystem of smart products, including water purifiers, refrigerators, range hoods, switches, speakers, fans, water dispensers, mirrors, gas and electric water heaters, water processing, dishwashers and more. |
More | You can read more GadgetGuy Viomi news and reviews here |
Strategic overview and essential checklist (from our Guide)
Item | Explanation | Grade | |
Shape | Round | All round robovacs have issues with edge and corner cleaning | Pass |
Lidar | 2D | 360° single LiDAR builds a 2D map – Gen 3 | Pass |
Sensor | IR | A forward IR sensor helps to avoid obstacles | Pass |
Maps | 5 | Stores up to 5, but you must take the base station to each level | Pass |
Map edit | Yes | All the usual including mop and no mop zones | Pass |
Mi Home App | App | Google Play Store or Apple App store Well designed and meets all typical needs. Modes include vacuum, mop or both, suction (Quite, standard, medium and strong), water volume (three levels), battery level and cleaning diary, area vacuum, S and Y shaped navigation pattern, up to seven schedules | Above average |
Edge | Poor ability to clean edges – same as all round robovacs | Fail | |
Carpet | It depends on carpet type – use a stronger suction setting | Pass | |
Sills | 20mm | Similar to all mop plate round robovacs | Pass |
Other Sensors | Collision and cliff | Typical forward bumper sensor and cliff detector stops it from going down stairs | Pass |
Suction | 2700Pa | On max | Pass+ |
Dustbin | 300ml | Adequate given self-empty function | Small |
Water | 250ml | Adequate for 120m2 or more – depends on setting | Average |
Battery life | Claimed 220 minutes, but the reality is about 150 minutes and 150m2 on standard. Approx 60 minutes 60m2 on maximum | ||
Battery | 5200mAh | Samsung quality 14.4V/3.47A/50W | Pass |
Wi-Fi | 2.4GHz | Pass | |
Size | (L x W x H): 35 x 35 x 9.8 cm x 3.8kg | ||
Dock | 3L dust bag | Recharge time is about 4.5 hours | Pass |
House prep – necessary
Despite a reasonably advanced Gen 3 LiDAR and IR sensor, it still only builds a 2D map – IR is more for real-time avoidance of smaller obstacles. So, you need to do a full house prep as outlined in our Guide. It did get tangled in overhanging wires.
Map – accurate but hard to set no-go zones
There is a conundrum here, and it is common to all combo robomops. Say you have a tiled bathroom (ensuite) off a carpeted bedroom; you need to set the no-mop zone to the carpet area. But it is not entirely accurate, and the mop pad is wet anyway as it passes over the carpet. The only solution is to place the robomop in the bathroom and close the door.
We also found it onerous to get accurate virtual walls and no-go zones – the indicators were not very precise.
Cleaning efficiency – vacuum is great on hard floors
While it has 2700Pa (that is on maximum settings), it is about 2000Pa on standard and 2500Pa on medium.
We ran it in standard mode for the first two weeks, and it cleaned 75% of the test detritus from hard floors. But its carpet cleaning was not efficient at all – only 20% leaving 80% behind. We upped the hard floor to medium for the next two weeks – and it achieved 80%. We tried medium for the short sisal carpet, and it gathered slightly more. The following week we tried strong, but it still left over 50% of the detritus.
This is a common issue with all round robovacs, and the lesson here is excellent on hard floors but not carpet, particularly short ribbed sisal type or longer pile.
Speed – standard mode is about 1m2 a minute but slows if you select Y-shape cleaning (more thorough).
The Dyson V15 ‘Lie’ Detector test
Since reviewing the Dyson V15 Detector whole of home stick vac with its laser dirt ID head, we run it over the same area once the robovac has finished. As you can see, it collected an awful lot of detritus that the robovac misses – yes, it is the same for all robovacs. The majority of this comes from the edges, sills, and carpet areas.
Mopping efficiency – maintenance only
This has a static ‘drag’ plate and three water levels. Static plates mean a wet microfibre cloth; it drags a damp mop pad over the floor. There is no downwards pressure or movement – it is just like a light wipe. And that is what you get. It will not remove milk, coffee, juice, or food stains – because there is no ‘elbow grease’ behind it.
You can set it to Y-clean, and it will clean in a slower Y-pattern, but it does not appear to do much.
You can tell if the water level is correct – too low, and it leaves dry streaks and too high, and it leaves too much moisture on the floor.
Noise (dB at 1m) – acceptable
- Quite: 64
- Standard: 70
- Medium: 73
- Strong: 76
Maintenance – easy and cheap
Standard – remove the rotary brush and remove hairs. Washable HEPA dust filter, microfibre mop pad and replaceable whisker.
AliExpress has replacement dust bags, HEPA and pre-filters for reasonable prices. You can also check eBay.
Caveats
The cleaning station is large and deep (550mm with the robovac) and requires more floor space and depth. You need to find an area that won’t interfere with the thoroughfare, and that is not as easy as it sounds as it needs 1.5m clear space in front and 1.5m on each side.
GadgetGuy’s take
After we review and rate test devices, we can then read third-party reviews to see if we are at odds with any findings.
The Viomi Alpha S9 gets good ratings for a round robovac/mop – and that is what we found. Its discount price is very tempting. But it is no better than any of the plethora of Gen 2 robovac/mops (including its V2 and V3 models review here 8/10). It just offers the convenience of self-emptying.
Would I buy it?
If I had mainly hard floors. But I have seen Gen 4 3D LiDAR robovacs and how they don’t need time-consuming house prep, and the robomops with ‘muscle’ do a vastly better job. Catch 22 – two devices! But, and we issue this reminder for all robovac buyers – you need a quality stick vac to do edges, stairs, and longer carpet.
Seeing that the Viomi S9 does save upto 5 maps to support multiple floors, do you know if it support similar functionality like the Roborock vacuum whereby one only needs to move the robot vacuum between floors without needing to move the charging dock? Refer to the following article about multi floor support for Roborock:
https://support.roborock.com/hc/en-us/articles/900002181666-How-to-create-multiple-maps-for-multi-level-house-
I am 90% sure that the charging dock needs to be moved. Here is all I could find
Once you have completed your first Map pick up the charging dock and move it to the next location and start the cleaning cycle again. It will show on your phone/Mi Home app as Map 1 for a while, this is ok, let it run! Your smart Robot Vacuum Cleaner and Mop will obviously figure out that the room is different from its currently saved map and start creating the new zone as an additional map. You can save it as Map 2 etc.
Thanks Ray – I’ve bit the bullet and decided to purchase the Viomi S9 and will update you once I have received it & completed some testing. I’ve been informed that the docking station is required when a new map is to be created but once the map has been created, you can just move the vacuum between floors and just select the correct map before starting the cleaning cycle.
It may be a case where the robot will go around “searching” for the docking station at the end of the cleaning cycle until it runs out of power if the docking station isn’t moved to the same floor but I’m hoping it will be smart enough to come back to the starting point and just stop there.
I look forward to your reader real-life contribution.
Hi you mention that its going for 549? Which website is it?
$599 is sale price now – here https://www.pcbyte.com.au/p/viomi-alpha-s9-robot-vacuum-dirt-disposal-black-223317
We purchased Viomi alpha s9 two months ago. The functions are advanced therefore initially we were very happy with it, however very quickly it began to malfunction. The error messages are in Mandarin and therefore we have no idea what it is saying. The dirt bag disposal no longer works, instead a message keeps telling us the bag is full. I have replaced the bag twice, it is completely empty, yet the vacuum is no longer emptying itself because it thinks the dirt bag is full. Now it stopped cleaning altogether. It literally goes over the dust without any suction.
I have made numerous attempts to get some help from the PC Byte (where we purchased it from) and Mi store, but had no support at all. Both have requested numerous things from me, such as photos, videos, invoice, etc, all of which has been provided to both. Mi Store is saying it’s the responsibility of PC Byte. PC Byte is simply not responding to my emails. All of my phone calls take hours on hold before either I am having to give up, or there is some malfunction and I lose my spot in the cue.
Needless to say, I am disappointed.
Thanks for the feedback. Viomi advised us that the official distributor was PC Byte (not Panmi) and we have had nothing to do with them. I will copy your comment and send it to PC Byte saying that our recommendation is at risk. If you get action please let us know.
I have the same issue as Kat. The dirt bag disposal works intermittently and the message keeps telling us the bag is full (when it is not). Very frustrating, as I am sure it could be fixed with a firmware update.
I passed Kat’s problem to PC Byte but have heard no more. If you bought from them lodge an email here https://www.pcbyte.com.au/contact-us
Hi Ray,
I just bought this machine. I did not move the charging dock. so the map I got is very confusing. I set the water level to 2 assuming 1is more water or 3 is least water? but I find it is really mop well.
How can I restart a new map. I didn’t save the map and looks like it saved itself.
Thanks
Sorry but after the review we sent the product back so my comments can only be general. The MiHome app allows you to save up to five maps so you should be able to make a new map and save it. Yes it will autosave the first map that you should be able to delete.
I have just purchased this and cannot seem to connect it to my wifi. When i try it states that “this device does not support 5 GHz”. Has anyone had this issue or have a solution?
It was the biggest mistake of my life. This brand does not offer any technical support. They don’t answer and when they answer, they sends you for a walk.
They only sell lies. Product specifications are incomplete and unrealistic.
6 months after buying a Viomi S9, the product started to show signs of operation problems. After the first firmware update, the product started to fail to clean even 50% of what it did at the beginning.
At the second firmware update, the device fails to clean even one room.
the battery drains very fast.
Given the answers I was recived from them, they should not sell in Europe.
I don’t know how they managed to homologate their products under the CE marking. Their products should not be sold in any store in Europe or world wide.
It’s a disgrace to Xiaomi company.
Seeing that I am not the only one who complains about their service, I come to believe that it is a marketing strategy in which they make the devices malfunction through Updates.
DONT BUY. WORST DEVICE EVER. WORST CUSTOMER SERVICE. WORST BRAND EVER.
They dont have any respects for their customers.
They should pay us to take their products… thats how bad they are
Hi, I am planning to buy Viomi Alpha S9 UV Robot Vacuum which comes with a UV sterilizer. Do you know if this is suitable for wooden floors as I am afraid the UV may damage the wooden surface?