Robomow RX12u Review

Robomow RX12u Review

Update March 2020

Please note that Robomow has introduced a new model called “Robomow RX 50u Connect” that will be available on the UK market towards the end of March 2020. This new robotic mower is equipped with the latest Lithium-ion battery technology and other enhanced features. I would therefore recommend that you do not purchase the Robomow Rx12u and RX20u due to its older technology, including the Lead Acid battery. If you are looking for a robotic mower of this size I would strongly recommend the WORX WR130E S300 OR wait to my full review of the new Robomow RX 50u (I will complete this review when available). The WORX WR130E S300 is packed full of the latest technology, and is my number 1 recommendation for lawns up to 300m².


The RX12u is the smallest and most affordable model Robomow have ever built. It is best suited to those with small gardens (upto 250m²) that are shaped a little more complex than most.

Because of its very smart navigation and mobility, the RX12u can handle these gardens much more effectively compared to other brands/models.

Now even though the RX12u is a smaller and cheaper mower, it still has the good mowing features that you would see on Robomow’s bigger and more expensive models.

Considering everything that this model is equipped with, it is difficult to match the value for money the RX12u provides.

But to see if it belong in your garden make sure you stick around as I’ll be reviewing all of its features, functions and capabilities.

Robomow RX12u compared to the Robomow RX20u.

How does this compare with it’s slightly bigger brother the Robomow RX20u?

The difference between the RX12u and the RX20u are in the ability to schedule cuts, which you get with the RX20u; as well as this, you get the android app connectivity and being able to mow in up to 5 zones with the RX20u. The RX20u also has a security key which renders the device useless if removed. If you don’t require the larger lawn coverage and these additional features then the RX12u is still a contender, with the convenient touch and mow button. Just hit go when you want to mow!

Main Features

  • Rating: 7.5/10
  • Covers Areas up to 250m² (preferably 150m²)
  • Hard to Beat Mobility
  • Easy Operation

Robomow Video

To get a glimpse of what the RX12u is capable of, watch the Robomow video below:

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Model Comparison
Mowers Robomow RX12u Flymo 1200R Husqvarna 105
Lawn Coverage (max) 250 m² 400 m² 600 m²
Noise Level 63 dB 58 dB 58 dB
Mowing Time 90 – 120 minutes 75 minutes 70 minutes
Charging Time 16 – 20 hours 60 minutes 50 minutes
Dimensions 53x42x26cm 58x46x25.5 cm 55x39x25cm
Weight 7.5 kg 7.4 kg 11.1 kg
Mobile App No No No
Slope Capability 8.5° 14° 14°
Rating 7.5/10 9.4/10 9/10


As I have already made clear, the RX12u has exceptionally good mobility, but why exactly is that? Well it comes down to a few things…

Smart Mow

Both RX models do NOT have the Smart Mow technology built in, this is only found on the RC and RS models.

However, Smart Mow alone is not enough to handle a complex garden, with many small spaces and narrow passages.

That is why Robomow have made the RX12u much smaller and compact than any other of their models. With this design it can squeeze through even the tightest of angles. This gives it a better chance of covering every inch of your garden.

And it can also travel along gentle slopes reaching 8.5° – which isn’t the best if I’m honest, the majority of robomowers can reach up anywhere between 20 – 22°.

This is not an issues if your lawn if flat, but just make sure to keep it in the back of your mind and consider before purchasing.

Driving System

Again this is slightly different from most models but just like above, it actually improves the mobility of the RX12u.

Instead of making use of the standard three wheels, Robomow decided to go with something a little more innovative.

Just like all Robomow models, it uses two big wheels at each side so that is stays balanced and steady. But instead of using a typical third wheel at the back, the RX12u has been fitted with a Glider.

This promotes better maneurverability as it gives the mower much more freedom and allows it to make turns with ease. Making it perfect for complex gardens.

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Power System

The RX12u mower is powered by a Lead Acid battery and electrical motor to produce between 90 to 120 minutes of mowing time.

For such a small mower this is pretty good and it should finish your lawn within this time, however it has a downside…

If it doesn’t finish the lawn in this time then you could be left waiting up to 16 to 20 HOURS for it to fully recharge. This is due to the mower being fitted with the older Lead Acid battery.

Considering the size of lawn it’s designed for the RX12u shouldn’t have a problem finishing your lawn in one go, but I have to say I was a little shocked when I saw this.

The reason behind such a poor charging time will be the fact that the mower makes use of a Lead Acid battery, these are less efficient than the much more common Lithium-Ion battery seen in all robomowers (or at least all the ones I’ve seen anyway).

Other than not being able to develop one to fit the RX12u, I can’t think to why Robomow wouldn’t fit this model with one.

I’d imagine this will be quite a turn off for most people and is definitely something they’ll need to work on going into 2020 (New Robomow RX 50u Connect model will be released in the UK late March 2020 – it has all the new features, including the latest Lithium-ion battery).

Mowing Features

Floating Deck

The Floating Deck feature allows the blade to move up and down with the slope of the ground. Meaning the RX12u can stay level with your garden, reaching every inch of grass.

So whenever the mower comes across any bumps or holes while on route, it will be able to cut it just as evenly as flat land.

Multi-Zone Feature

So that this model can take care of a whole range of complex gardens, like all Robomow mowers, it can travel between separate lawns (5 of them).

There’s no need for you to lift it from one to the other, as long as there is a passage of some sort it can make its own way there.

However you will need to make sure the perimeter wire surrounds all lawns and that the passage is not too narrow (see user manual for exact measurement).

This shouldn’t make the installation process any more difficult but I guess that depends on your lawn. And even if it is a little trickier, this saves you the effort of dragging the unit from one to the other. So I think it will be worth your time anyway.

Rain Sensor

The RX range of robotic mowers do NOT come with a rain sensor. Rain sensors are found on the RS and RC Robomow robotic mowers.

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Narrow Paths

In order for this mower to work properly around your lawn, you need to ensure that there is at least 15cm of space between one length of perimeter wire and another.

Just make sure you keep this in mind before your purchase. If you have any areas of lawn which are narrower than the RX12u it will not then be able to pass through, never-mind mow it.

Robomow App

The Robomow RX12u does NOT have the app functionality. You would need to purchase the next RX model up, the RX20u – if you wanted this feature.

Robomow RX20Blade

The RX12u is equipped with a slightly different blade than other Robomow models. It is a little smaller and only has two edges, probably to account for its smaller size.

But don’t worry – it is still just as effective. Built strong and tough, this blade gives you a flawless cut and will only need to be replaced once a season, saving you time and effort.

And as I mentioned earlier, you can adjust its cutting height (between 15 to 45mm) for the changing seasons and lawn conditions.


For the benefit of your garden’s health and so that you don’t have to collect all those pesky clippings, the RX12u cuts your grass into small pieces.

So small in fact, that you cannot see them after mowing because they have fallen all the way down to the bottom soil. This is where the magic happens.

The clippings will begin to decompose and act as a fertiliser (mulch), providing nutrients for the soil to improve its growth and overall health. This results in a much fuller, greener and better looking lawn.

So not only will the RX12u maintain your lawn, but it will also improve it as well.

Mowing Modes

So that the RX12u can fit into different environments and adapt to different situations, you can program it to operate differently.

This is done through a selection of gardening modes, which I will explain in more detail below…

Turbo Mode

The Robomow RX12u does NOT have the Turbomow feature. This feature can be found on the RS and RC models.

Eco Mode

So that the RX12u operates using minimal energy for cutting your grass and maintaining your garden, you can set it into ‘Eco Mode’. When you want to save a little bit of energy this feature is ideal.

However be warned this does slow down the RX12u work rate, so it will take longer to finish the mowing.

Edge Mode

Now this is the most useful of all modes – the ‘Edge Mode’. This program instructs the RX12u to follow the perimeter wire and cut only the borders of your garden.

Giving it a chance to reach and cut the outer limits of your lawn.

However the problem is still not quite solved yet.

If your garden is next to the wall of your house or a fence, the RX12u can still not cut the grass beside it. So after every mow, you will have to go out with the trimmers and clean this up.

This can be quite annoying but I think it’s more than a worthy trade for mowing the entire lawn yourself.

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Safety Features

Bump Sensors

Okay so you probably have some garden accessories on your lawn like chairs, potted plants and trees. Well wouldn’t it be a shame if your brand new mower ran off course and started eating these.

I think you wouldn’t be best pleased and you’d probably want a refund – I would too.

Well no need to worry the RX12u comes with its own bump sensors.

So whenever it comes into the slightest contact with any of these obstacles, it will stop immediately and turn off its blade, recalculate a new route to follow, move backwards a couple of spaces and turn to mow in a different direction.

Keeping everything – including and especially you – safe when it’s away at work.

Lift & Tilt Sensors

The RX12u is equipped with sensors that turn off the blades immediately when the mower is either lifted or tilted. So if you need to replace or clean the blades, don’t feel scared or cautious, you will not be in harm’s way.

Although if you can be a little overcautious at times (like me) then lift from the back of the mower. This is furthest point away from the blades and there’s a handle to grab hold on.

PIN & Alarm System

To protect your mower from being stolen and so that others can’t use it unauthorised, the RX12u comes with a PIN code.

The mower also comes with a Child Lock to prevent anyone unfamiliar with safe operation from operating it freely.


  1. Old battery technology.
  2. Because of the mowers shape and the size of blade, it can’t reach grass beside a wall or fence. This means you’ll have to get the trimmer out once in a while for that perfect edge to edge finish.
  3. For the Bluetooth connection to work you need to be standing quite near the mower, so you can’t control it from the comfort of your sofa.
  4. The Charging time of 16 – 20 hours is a very long time to wait before the RX12u can get back to action. But considering the size of lawn it is built for it should finish mowing your lawn in one go.

In summary, there isn’t all that wrong with the RX12u if you compare it to other models. This model has so many good qualities that having a couple of flaws is more than acceptable.

Robomow RX20Conclusion

As you can probably tell from my tone just above, in 2017 I was really impressed with the RX12u. However things and technology has now moved on and there are much better alternative robotic mowers available on the market today.

Features like the Floating Deck and the Glider really do make this perfect for the small, complex garden. And not only that but things are included that you usually only find on a high end model – like the mobile connection and multi-zone feature.

If you have a small garden and are in the market, then this model could be an option for you, however I would strongly recommend that you wait for the new Robomow RX 50u Connect (will be released late March 2020) or consider the new WORX range of robotic mowers – these are my top picks due to their features, value for money and performance. 

Should You Buy This Mower?

Even though this is a great mower, it doesn’t fit everyone’s garden. So to help you understand whether or not it deserves a place in your garden and if you’ll take full advantage of its features, below I have listed its perfect customer-

  • Your garden is not larger than 250 m²
  • Your garden is complex in shape so will make use of the RX12u mobility
  • Your garden is separated between 2 lawns that are connected to one another via a pathway
  • Your lawn has slopes under 8.5°
  • You do NOT require the Robomow app
  • You don’t mind doing a little bit of trimming every now and then
  • Someone who doesn’t mind longer charge time 16 to 20 hours

The following installation kit is supplied with this mower: Installation Kit Included (70m Perimeter Wire, 80 Pegs, Connectors, Base Station Etc).

Hopefully these pointers have made it clear if you’re suitable for the RX12u. Please see my March 2020 update at the top of this review. There are other more suitable options available on the market at the moment with latest technology (this model is now too dated and less efficient compared to other models/brands).

If you want to check out the latest prices make sure you click on the link below to see the latest price.

Where can I purchase this model?

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Additional Specifications
Working Area 200 – 300 m²
Max Incline 8.5°
Battery Type Lead Acid
Battery Power 26V
Mowing Power 100W
Typical Charging Time 16 – 20 hours
Typical Mowing Time 90 – 120 minutes
Cutting Height (min-max) 15-45 mm
Cutting Width 15-45 mm
Sound Level ECO mode: 64 dB Measured – 67.9 dB Guaranteed – 69 Db
No. Of Zones 5
Alarm Yes
PIN Code Yes
Rain Sensor Yes
Floating Deck Yes
Lift Sensor Yes
Tilt Sensor Yes
Perimeter Wire 100m or 200m
Product Size LxWxH 53x42x26cm
Weight 7.5 kg
Lawnmower Product Expert, Reviewer and Author at | 01284 615144 | | Website | + posts

As a seasoned expert in the field of garden power tools, I have dedicated over a decade to working with and reviewing a wide variety of lawn mowers. My extensive experience has allowed me to gain a deep understanding of the benefits and limitations of different types of mowers and garden tools.

Over the years, I have honed my skills in writing informative articles and creating helpful videos for various blogs and publications. This has given me the ability to not only recognise what makes a good lawn mower, but also to help you choose the perfect garden tool for your specific needs and requirements.

With my wealth of knowledge and expertise, I am confident that I can provide you with valuable insights and recommendations when it comes to selecting the right lawn mower for your lawn. So, whether you're looking for a battery cordless, electric, petrol, or robotic mower, you can trust in my expertise to guide you towards the best option for your garden.

2 thoughts on “Robomow RX12u Review”

  1. Hi Mark!

    Excellent review I must say!

    Is there any difference in batteri and charging adapter compared to the rx20u?

    Thank you!

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