Robomow RX20u Review – Upgrade from Robomower Rx12u or just more cash?

Robomow RX20u Review

Robomow RX20u Robotic mowers are pretty to look at but how well will it cut your lawn? Is it really a worthy upgrade from the Robomow RX12u or is it just more expensive? Find out in the Robomow RX20u review below why you are paying an extra $200.

Product: Robomow RX20u

Company: Robomow

Model: RX20u  

General Market Price: USD $850-950

Where to buy New for best price online: eBay at USD $795

Warranty: 1 year

Stars from C-ELMR :

What’s in the box? Take a look at this unboxing video of the Robomow RX20u

NB. Looks exactly the same as the Robomow RX12u

What is the Robomow RX20u and how does this little robot manage to cut your lawn?

The Robomow RX20u works in the same general manner as other robotic mowers. Without getting too “techy” It works within the boundaries of a low voltage guide wire to cut within the boundaries you set.

All you need to do is set up the guide wires around the boundaries of your lawn, set up the charging station, connect it to a power outlet and press start and the mower will be off to do its job.

A remote control feature is also available with this robotic mower. This is a plus.

The review of the Robomow RX20u will cover the following:


Ease of Use

Power, Performance and Efficiency

Durability and Ease of locating replacement parts

Customer service from company

Value Versus Cost to Run

Other Viable Robotic Mower Options

Before we begin, tale a look at all that Robomow had to say about their RX20u mower! How much of it do you think is true?

Jump to Review Summary….

Design – what is really going on inside of the Robomow RX20u? 

The company had a lot to say but what is really going on inside of the Robomow RX20u? Take a look at these Specs.

Robomow RX20u specs

From those specs you can see that this Robomow is small, light and very neat but it is not packing much. Let’s break down the specs and show you what they really mean for your lawn.

Height of grass cut

It has a very limited range of 0.5 to 1.7 inches. There is no improvement here from the Robomow RX12u. You would still need to groom your lawn so that it is lower than 1.7 inches before you use this mower on it. If not, it will just get stuck, bogged down by your tall grass.

Also, Robomow RX mowers do not have the smart cut feature to accommodate to the difference in grass growth rate you will experience in the different seasons. Therefore, as seen with the Robomow RX12u, you will be left with overgrown lawn in the rainy season unless you schedule a full 9 hr per week mowing time. Other robotic mowers (such as the Husqvarna Automowers) have smart cut feature.

Size and Weight

Like the Robomow RX12u, this is a very simple mower and is therefore very small, light and easily transported. The two RX mowers are really the smallest that I have seen so far. They are the same size.

User interface – The Robomow RX20u has an App!

It has a manual start and stop option but it has the intelligence to return to the charging station when it is dying. The upgrade is with the App feature available with the RX20u and not the RX12u.

Robomow RX20u comes with a built-in Bluetooth LE (Low Energy) device that allows to control your mower from your smartphone. A free complementary Android mobile app can be downloaded by scanning QR code found in the manual.

The app allows you to:

  • Activate theft protection
  • Set automatic mowing schedule
  • Drive your mower via remote controlling, especially for making patterns in your lawn
  • Define additional starting points
  • Get access to diagnostics team from the app by a service station.


The range of wireless connection between the Robomow App and your mower varies between 10 to 25 meters under normal conditions, depending on the mower’s orientation (side, front, or back). Note that when you are facing away from the mower, the range is reduced approximately by half. 5.3 CONNECTION

For safety reasons, the communication link with a mower in Remote Control mode is very sensitive and thus less tolerant to communication errors. This requires a shorter range with the mower than in other Robomow App modes.
Either way, you need to maintain line of sight and no more than 3 meters (10 ft.) distance when operating the mower in Remote Control mode.

Safety Features – Not very impressive

Definitely an upgrade from the Robomow RX12u except it still has a pet safety issue.

Robomow warning

So is this robotic mower pet safe?

No. Absolutely Not. So if you have a dog who loves the grass, not for you unless you plan to sacrifice his play time for your mow time

Child lock feature – Is it safe to leave the mower running with your kids on the lawn?

No, there are clear warnings in the manual about this.

“The Child Lock prevents unintended operation of Robomow by an accidental press of one of the buttons. Only pressing two buttons in the right order will initiate the operation. It is required to activate the Child Lock feature if children under age 6 may come in contact with Robomow”

(Robomow RX20 manual)

You can however, manually lock the mower or use the app to lock it so that a child cannot turn it on without you first unlocking it from your device or them knowing that two buttons that should be pressed simultaneously. To enable child protection, press and hold the GO + STOP buttons together for 6 seconds. If you wish to disable child protection, press and hold the GO + STOP buttons together for 6 seconds again. The app lock feature is a very convenient upgrade.

What happens if it is lifted, tilted or topples over?

Here is where another upgrade comes in. The blades will stop automatically if i is tilted or lifted.

What about anti-theft features?

Yes, this has a good anti-theft feature that integrates with the app. You can lock the Robomow RX20u using the Robomow App. Anyone without a registered mobile device cannot get it to operate again without some real computer skills.

Does Robomow RX12u have a rain sensor?

Well no, and it will get wet if you do not get a house for it. It is not weather proof so you should take the time  to build or buy a house for this mower to live outside or place the charging station inside the garage or any other dry area.

Ease of use – The Installation Process

The installation process is pretty simple, not unlike any other robotic lawnmower. All you need except pliers, hammer and a wire clipper, are found in the package. It comes with a very straight forward manual and Robomow has a great video on YouTube showing you the steps. There is no additional programming required for the mower to work.

Manually, all you need to do is lay out the guide wires, set up the charging station and press the red power option on the mower. When you need the mower to stop working, press the power button to turn it off. The only annoyance with the installation process is the time it takes to lay the guide wires around your lawn but if you are impatient, you can hire someone to do it.

Take a look at the video below showing the installation process. 


What about the Robomow App?

Using the app, A mowing schedule can be programmed into the bot so that it will cut your grass at set times during the week. To get the app, you can search play store or scan the QS code found in the manual. You will use your email and a password to create an account as well as the serial number on the mower.

This also has its own manual outlining everything in spectacular detail. It took me about 30 minutes to read the entire thing. It is just like any other command app. No hassle at all to use.

How hard is it to do battery changes?

Not very hard. Take a look at the video below.

Power, Performance and Efficiency (!!)

This mower performs well on small flat lawns. It will do the job efficiently but there are some drawbacks. According to customers who purchased the Robomow RX20u, these were the major advantages and disadvantages with power, performance and efficiency of the mower:

The good

  1. It will maintain the manicured look if you have a flat lawn
  2. It turns if it bumps into an object.
  3. It has managed to get into all of the corners and edges,
  4. It is VERY quiet.
  5. The unit is light weight, and isn’t designed for steep hills but it sure handles to lumps/bumps
  6. Only uses RX20u about 4kWh per month (about 48p per month).
  7. The wheels are knobby and the rubber is soft with grooves to reduce slippage and lawn damage from spinning wheels.
  8. The cutting height is easily adjusted with a small knob on the side of the unit, with a handful of pre-set heights. Most people get best results from starting at the highest height adjustment then gradually going down to get the plush carpet look
  9. There’s never any clumps of clippings lying around because the mower mulches efficiently. The tiny clippings fertilizes the lawn making it  greener and more weed resistant.
  10. It finds the charging station if it is installed properly in a flat, clear area. If it is having difficulty reaching the station due to obstacles in its way, the app can be used to draw a perimeter around the problematic path for it to get to the charging base easier.

The bad

  1. It hardly finds its charging station on its own unless you find the perfect spot for it.
  2. It absolutely does not handle the lawn well unless the grass growth is slow and your lawn is 180 m. sq. or less.
  3. It does not handle slopes well so you need a flat lawn for it to work well without leaving overgrown patches. Also, it will get stuck at the bottom of the slope, spinning in circles unless you move it. To avoid this, you need to place perimeter wire around the slope and cut them manually or with an upgraded version of this Robomow.
  4. It takes too long to charge (16-20 hrs!)  compared to the work time (90 – 130 minutes). This is because it uses lead acid batteries instead of the lithium ion batteries that we prefer.

Durability and Ease of locating replacement parts

The mower was described by one customer as having very sturdy material. The blades are said to last up to a year after which they must be replaced. There is a 1 year warranty on the entire mower so if anything happens to it within this time, it will be fixed by the company for you. Replacement blades can be found for you on their official Website as well as on Amazon and eBay.

Customer service from company

They replied to my email within 24 hours and answered all my questions well.

Diagnostics – security alerts directly to your smartphone. Awesome

The RX20u can also be equipped with a GSM card which sends operational and security alerts directly to your smartphone. With the GSM card, the RX20u can also collect technical data, diagnose faults and communicate directly with the Robomow support team so that they can help you if necessary. I am yet to see complaints about their diagnostics team so they get full marks here.

Value Versus Cost to Run

Who would I recommend this mower for? Would it be on any value to you?

  • People with small, flat, uncomplicated lawns.
  • Elderly
  • Disabled
  • Busy individuals
  • Looking to spend more time with the family
  • People who hate mowing
  • Do not feel secure allowing strangers to cut your lawn
  • Commercial use

Who would I discourage from buying this mower?

  • People with unchained animal
  • People with lawns bigger than 180 m. sq. with thick, fast growing grass.
  • Lawns with slopes
  • Lawns with complicated connections

Thoughts on Value – Robotic mowers are not expensive to run. This RX20u will use about 4kWh per month (about 48p per month). You will need to change blades and batteries once per year. Otherwise, you should be fine. I would say this mower is worth the purchase and yes, it is an upgrade from the Robomow rx12u. (Read review from the suggested posts below)

Other Viable Options for small lawns

  1. Miimo 310 – View Full Review here miimo 310
  2. Worx Landroid – View full review here – Personal Favorite 
  3. Husqvarna 315 –  View price and reviews on Amazon
  4. Gardena –View price and reviews on Amazon
  5. McCulluh –  View price and reviews on Amazon 

Review Overview

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I am a lover of people and all things natural. Big tree huger alert but I love when things work the way that they were meant to. Eco-Friendly does not mean that people should suffer to make it happen. My reviews here will help you to find the best Eco-Friendly alternative to your gas mower. If the electric mower is trash, you can trust and believe that I will give it a bad review, tree hugger or not.

13 Replies to “Robomow RX20u Review – Upgrade from Robomower Rx12u or just more cash?

  1. I read your review of the Robo Mower Rx20u and quite honestly it would not be my first choice of mower. As was pointed out it is adequate if the lawn is short to start with and the area is nice and flat but as a gardener myself,lots of gardens have sloping areas and tiered sections that require man powered mowers. The child and pet safety factors are not ideal for domestic use. i can see that this type of mower would be ideal for sports ground where flat short lawns are needed all year round.

  2. I have read your review of the Robo mower Rx2ou and to be quit honest , as a gardener myself, it is not what i would personally choose. As what was pointed out, if your garden was nice and flat with the grass reasonably short to start, that is ideal. But many gardens have slopes, tiers and other surfaces that require more physical involvement with a more traditional man powered mower. The pet and child safety factors are not adequate for domestic use, so that is a no no. I can see that this machine would be an ideal mower for sport fields where level grounds are essential.

    1. Hey there,
      I can see your point. You are right. This mower is either for commercial use or for people who do not have unchained pets or kids.

  3. Many thanks for all your hard work in reviewing this cordless mower under the Robomow brand, I have used a gas mower all my life but I am finding it more and more difficult to keep on top of it so my wife had mentioned this robotic mower and stated that we should consider this option instead, the level of detail is great, I also like the remote control feature, one question, how does it operate in hilly areas?

    1. Hi Justin,

      I’m afraid this little robot will not do you any justice in hilly terrain. It stops at the bottom of the slope at about 6 Degrees and gets confused trying to mount it. This will only work for small, flat lawns.There are other Robomow robotic mowers equipped to deal with slopes. Also, read the Worx Landroid Robotic Mower Review, the MIIMO robotic mower reviews and the Husqvarna Robotic Mower Reviews. Those will do your lawn some justice. 

  4. Wow, it sounds just like what I need ! But i never thought of comparing, thank you so much for listing the pros and cons of this model. Is there a model (simple and easy to handle) that you would recommend ? Our lawn is pretty much square and has no fancy edging.
    Appreciate the feedback thank you so much.

    1. Hi Cath,

      The Husqvarna line of automowers are really my “go-to guys” when it comes to power, performance, efficiency and ease of use. They really work independently to get the job do for you. A less expensive choice would be Worx Landroid. It really gets the job done without stopping and getting confused over minor slopes and patches in the lawn. Read the reviews and then decide from there. You could also go to our “Contact C-ELMR” page and fill out a request form for a mower for your lawn. We give great suggestions based on your budget and lawn type.

  5. Hello
    I didn’t know they made a product like the Robommow RX20u how convenient is that? Do you see the guide wires? If you have to groom the lawn first you might just as well mow it yourself don’t you think?

    That is so cool that it returns to it’s charging station when it’s dying. Modern technology has really come a long way when you can control your mower on your smart phone. It is a pretty neat product and it looks nice.

    1. Hey Angie,

      So you would mow it before letting the robomow loose on your lawn because it would not be able to cut the tall grass. After that first mow, the robomow will keep your lawn kept so that you will never need to mow again…except in the rainy season. It was built to do the work for you. There are other robot mowers that can handle tall grass and rain but they still recommend that you mow the lawn initially before you start using the automowers…think of it like the last mow of your life. 

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