Bill Bennett writes: My first inclination was to turn down the offer to review Deebot Ozmo 90, a robot vacuum cleaner
and mopper. At the time I was too busy. Jo overhead the phone conversation and told me to call back - she was keen. So
keen I left her to write the review:
Dennis, or, to use his proper name; Deebot Ozmo 900, has the wrong voice. It is a woman’s voice. As a modern girl I
don’t believe vacuuming is a woman’s job.
The man of the house thinks he sounds like a female version of the toaster in the 1980’s science fiction sitcomRed Dwarfabout Dave Lister, the space-ship snack-machine repairman who wakes up alone three million years in the future after his
ship suffers a fatal radiation leak.
Actually, Dennis does have a futuristic look. He is a smooth white disc (320 mm in diameter, 70 mm high) who trundles
around on rollers and comes equipped with a laser distance sensor (LDS), a bumper and anti-collision sensors.
He also has a docking station that you plug into an electrical socket. However, although he may sound likeRed Dwarf’s toaster, his software is better. He can build room maps and he comes with an app (Google Assistant and Alexa enabled).
Like lots of people who have tried him out, I quickly came to think of Dennis as a lovable, useful pet.
It’s hard not to develop affection for a machine that tells you when he’s tired. That is when his battery is low. He
then trundles off to his docking station for a rest (recharge). Dennis’ formal name is Deebot Ozmo 900. He is the latest
robot vacuum cleaner from Ecovacs Robotics.
He is also the latest in a long line of slowly improving robot cleaners. There is still a way to go, but for many people
Dennis would be a boon. Where he really scores is that he mops as well as vacuums. I have criticisms of Dennis and I
will come to these later, but he is a huge help around the house.
He is cordless and can run for up to 90 minutes when the cleaning is easy – less when mopping as vacuuming and mopping
at the same time as this uses more battery power.
He would be a great help for mothers with messy young children, the elderly and those with a mild disability or
infirmity. However, he needs supervision. He is a bit like a two-year-old in that he gets stuck and calls for help.
Cables plus our television sideboard proved a problem for him. But I could work on my laptop while keeping an ear cocked
for when he got into trouble.
Death to dust bunnies
What I really loved though was how Dennis dealt with dust bunnies. Vacuuming these up a hateful job as it involves
grovelling next to beds manipulating our Dyson vacuum cleaner’s wand extension. Dennis, in comparison, gaily scoots
under the beds and vacuums up the bunnies with ease.
On the minus side, because he often gets stuck I don’t think his accompanying phone app is very useful. What would you
do if you set him to work from the app while at the office and he got marooned in a corner?
The app is also difficult to install. There has been a lot of flak in the online support forums and elsewhere about
this. I got the impression Ecovacs is more focused on robotics than apps, with the app just being something it feels it
has to provide.
Other criticisms: Dennis’ mapping limitations. Ours is a split-level home and Dennis is designed to create just the one
map. He kept having to create new maps.
In practice this isn’t a big issue, except I think this is why he gets stuck backing away from our sideboard, needing
frequent rescuing. Other minor issues are his bin is small. It needs frequent emptying. Similarly, the water reservoir
for mopping is also small. It quickly runs out of water. But the mop pad is excellent for cleaning a laminated floor
like ours as the boards swell up with too much water.
Dennis is best suited to hard floors. While he worked well on our low-pile Turkish rug, I could see deep pile carpeting
would be beyond his suction capacity. He would work well with wall-to-wall low pile though.
On the plus side, after using him several times in one week, our house smelt fresher and breathing was easier. I get
asthma and he obviously picked up a lot of dust, pollen and pet dander.
Because he is a robot, users would be likely to use him often and so keep more on top of cleaning.
No longer a luxury product
The competition: other robots and the Dyson cordless stick cleaners.
Dennis – aka the Deebot Ozmo 900 – is an affordable robot at NZ$800. Not long ago, robot vacuum cleaners were a luxury.
While Dennis can’t do everything, ie, vacuum curtains and furniture, he is excellent at what he does do.
A competitor would be the Dyson range of five cordless stick vacuum cleaners. These range in price from $900 to $1400.
While I haven’t tried them, I did lift one up in a store and found it quite heavy and unwieldly. The big battery sits on
the stick handle. For families whose vacuuming involves lots of quick clean-ups this could suit, although I think being
able to leave a vacuum cleaner to get on with the job is preferable.
To be fair, this isn’t a like-for-like comparison. The best way to think of a robot such as Dennis is as the vacuum
cleaner equivalent of the washing machine. Both get on with the job largely unattended. Normal vacuum cleaners are a
different kind of beast.
More pros and cons:
Dennis is squat and circular and not very tall – 100 mm at his tallest, where his LDS disc sits. This makes him good for
sucking up under-bed dust bunnies. However, it takes a while to get going with him as his manual is short and a bit
He also needs more maintenance than my old-style Dyson. For instance, his main ‘rolling’ brushes clogs up with hairs
these need cutting away. But he does a wonderful mopping job.
He does get stuck often. I think this is because his map is confused as we have split floors and he can only create one
map – he kept re-creating this. Ecovacs could upgrade here, providing Dennis with the ability to create two or more
maps. This would make him useful in small hotels as well as multi-storey homes.
Also, the LDS disc that sits on top of Dennis’ main body proved to be the same height as the bottom of our sideboard –
this could be why he kept returning to this same spot and getting stuck.
Deebot Ozmo 900 mops as well
On the plus side, the fact that Dennis mops too is a major bonus, especially with messy pets and their muddy paws.
Some robot vacuum cleaner reviews describe robots falling down stairs. To guard against this, I set up obstacles –
mainly cushions – as advised by the manual. This proved unnecessary as Dennis’ sensors easily detected the stairs; he
stopped and turned around.
The man of the house commented that it was good to know all you needed was a couple of cushions to stop a dalek
invasion. Clearly, he watched too muchDr Whoin his youth. Happily, Dennis doesn’t have a murderous Dalek personality.