Robotic Lawn Mowers Buying Guide

Buying a robotic lawnmower is an investment, so you should take plenty of time to choose one. You’re buying a modern helper, whose features and parameters you must be satisfied with down to the smallest detail. The content of this article will help you in this respect.

We’ll focus on all the essentials related to the choice of the machine according to the area to be mowed, the width and height of the cut, and the control itself. We’ll outline the basic and advanced functions of these products, with which you can achieve fully automatic lawn mowing.

And to make matters worse, you’ll also learn about regular and important maintenance, including setting the right area for mowing. This is how robotic lawnmowers know where to mow.

How to choose a robotic lawnmower in a nutshell:

  • Area – Choose a mower based on the size of your garden. The size of your lawn will determine the battery life and size of the mower, as well as its power and reach. You’ll always find the maximum area in ft² (m²) as the first parameter for a given mower.
  • Slope – If you have sloping terrain, keep this in mind when making your choice. Different mower models can cope with different gradients, which are given in percentages. In addition, keep an eye on the allowable slope inside the work area and inside the charging station.
  • Endurance per charge – The longer the endurance, the shorter the time it takes for the mower to mow the garden. The most common value is around 60 minutes. After that, the mower must be charged at the station before it can continue working.
  • Terrain roughness – If you have various obstacles close together in your garden (trees, bushes, rockeries, etc.) make sure the mower can pass between them.
  • Grass cutting height – The cutting height is usually adjustable between 0.8 and 2.4 inches (20 and 60 mm). However, some models will cut grass up to 4 inches (100 mm).
  • Functions and controls – Be clear about what you expect from the mower and what features you’ll use. The basics are safety sensors and anti-theft security. Some models can be controlled remotely by connecting to an app.
  • Noise – The mower will be in use for a large part of the day, so it should be as quiet as possible. The usual value is up to 60 dB, mowers with higher volume can be considered noisy.

Working principle of the robotic lawnmower

Robotic lawnmowers often referred to as automatic mowers, were until recently the dream of gardeners. Today, they’re slowly becoming a common, but more importantly also affordable product range offered by many companies. The overall design varies depending on which model you prefer. In the storage position, the mowers are roughly this size:

  • Length approx. 22-34 inches (55-85 cm)
  • Width approx. 16-26 inches (40-65 cm)
  • Height approx. 8-14 inches (20-35 cm)

The robotic lawnmower is driven by wheels, and the rear wheels, driven by an electric motor, are larger in order to transfer sufficient engine power to the lawn. There are one or two smaller wheels at the front, which are used to turn the mower. The wheels are either plastic or rubber. If you choose wheels with a rougher tread, the mower will get better mobility in rough terrain.

You should also know that the robotic lawn mower isn’t equipped with any collection basket. It doesn’t collect the grass but trims it by a few millimeters at frequent intervals. This is actually a mulching process, where the grass cutting is chopped into the smallest possible particles and spread over the lawn. This is usually done using three separate blades or a conventional mower blade.

Perimeter wire

Unlike robotic vacuum cleaners, the area maintained by a robotic mower isn’t surrounded by walls. Orientation in the space is therefore slightly more difficult. To prevent the mower from leaving the designated area, a boundary wire or perimeter wire is placed in the grass or a few centimeters below the surface to orient the device. It forms a sort of loop from the charging station, around the garden, and back again. See the separate chapter for more information on the correct laying of the guide wire.

Robotics mowers without perimeter wire

As technology advances, robotic lawnmowers are also getting rid of their wires. Gradually, they’re coming to the market without a circuit wire. They orient themselves in space according to the reference station you place in your garden and satellites. They use GPS or Galileo, and some models communicate with both systems.

Mowers without a wire are suitable for large areas, parks, sports fields, and anywhere there’s a good view of the sky. They simply won’t cope in a garden with many trees or a covered seating area. It should be mentioned that these mowers are still in their infancy and their high purchase prices reflect this.

Disadvantages of robotic lawnmowers

Although mowing without work sounds tempting, there are a few drawbacks. We’ve introduced the first one – the perimeter wire. If you don’t want to invest a really high amount of money, you’ll need to wire the entire garden. Robotic mowers are only suitable for manicured lawns, they’re not suitable for tall grass or grassy lawns.

You’ll also need to find a place for a charging station, which should ideally be under the roof but with access to the lawn. Then the purchase price is a chapter in itself. But this is made up for by the time saved, which you can spend on more pleasant things than mowing the grass.

Power source

Robotic lawnmowers are equipped with an electric motor with a battery, as is the case with some types of classic, spindle, and string mowers or brushcutters. And in the case of a robotic mower, this is probably one of the most essential components ever.

Today, you’ll find Li-Ion batteries in almost all products, which are both resistant to frequent and irregular recharging as standard and boast a long service life. The ability to maintain high speeds for longer also speaks in favor of lithium batters, which also speaks volumes about the overall performance of the product. Robotic lawnmowers are equipped with a single battery.

Lifetime

The lifetime is given in a number of charging cycles, which can be up to 900. This corresponds to approximately five years of use, again depending on the size of the mowed area and the frequency of mowing. However, the battery capacity may decrease during use. After a certain period of time, you’ll need to slightly adjust the timing of the mowing mode, as it will no longer match the characteristics of the mower.

When buying, be sure to avoid any older battery models, such as Ni-Mh, which not only have shorter run times but also a very limited lifespan.

Alternatively, solar robotic mowers are still an option. These are recharged from a solar panel integrated into their body. However, their market presence is still minimal.

Operating and charging time

The battery used in the mower has an impact on the running time and thus also on the area that the mower is able to cut per charge cycle. In general, the longer the battery life, the better. At present, we can find mowers on the market with an endurance of a few tens of minutes to a few horses – from about 45 minutes to 250 minutes.

However, other factors, such as the slope and roughness of the terrain, also have an impact on endurance. When browsing technical specifications, you may also come across a figure for the area mowed per battery charge. This is based on a battery capacity of roughly 160 to 990 ft² (50 m² to 300 m²). Note that the height of the lawn also plays a significant role here. If the lawn is higher, the robotic lawnmower will use more energy than if it is lower. The same proportion applies to the slope. The more challenging the terrain, the smaller the area the mower can mow on a single charge.

Often, the mower won’t be able to mow the entire garden on a single charge and will need to recharge at the station while it’s working. Therefore, another parameter to be taken into account is the charging and reach of the mower.

Charger and charging cycle length

As you can probably guess, the time it takes for the robotic lawnmower to charge up to 100 percent and be ready to go back to the garden is an important figure. The charging time is given in minutes. This parameter depends on the type of charger. Most often, it ranges from 40 to 180 minutes.

In relation to the charger itself, you should be interested in the length of the power cable, for example, depending on where you place it. It should definitely be in a place that’s perfectly protected from rain. It is, after all, a 230 V mains-powered device. In terms of space, the charging stations are approximately the following dimensions:

  • Length of the station approx. 24-35 inches (60-90 cm)
  • Widht of the station approx. 10-30 inches (25-75 cm)
  • Heigh of the station approx. 6-16 inches (15-40 cm)

It’s also important to mention the charging method for robotic lawnmowers. These are so intelligent that you don’t have to worry about charging them at all. The automatic mowers themselves detect that the battery is running low and drive to the charging station without any external intervention. It starts and recharges the battery. The mower then goes back out into the garden and cuts the grass. This process is repeated until it has mowed the desired area.

Robotic lawnmower performance

Compared to many other garden machines, the performance of a robotic lawnmower is measured on a different scale than we’re used to. It’s not horsepower, kilowatts, and the like. Power is presented in mowed area per hour, or square meters per hour. Although this is a very important figure, most manufacturers don’t include it in their technical specifications.

Typically, the mower can mow between 330 to 990 ft² (100 and 300 m²) per hour. It depends on its speed, but also on the width of the cut. How long it takes to mow your garden will also depend on the operating time per charge.

As this is a fairly kept parameter, you can make your choice based on the area you’re looking for. For each mower, the manufacturer recommends the maximum area for which the mower is suitable. Thus, you can encounter models for 1,640, 3,940, or 6,500 ft² (500 m²,  1,200 m², or 2,000 m²), for example.

Cutting height and width

Before you start choosing a robotic mower, you should consider what kind of lawn you have and what you require. The width and height of the reach of the robotic lawn mower.

The cutting height is particularly important in this respect. This can vary more or less from one mower model to another. On average, however, you may find a cutting height of between 20 and 65 mm. The adjustment can be infinitely variable from minimum to maximum or graduated to several positions with corresponding lengths.

In this context, we’ll give you one more recommendation. Before you even unleash your new robotic lawnmower on your lawn, first mow it thoroughly with a conventional mower to get it to the desired height. The mower will then maintain this. Mowing grass that’s too tall could be a problem for the robotic lawnmower. There’s one crucial thing to remember here. Robotic lawnmowers are used for regular mowing and maintenance, not for a one-off cut every few days or weeks.

Coverage

Just like conventional mowers, robotic mowers differ in the overall coverage of the mowed area. It makes a big difference whether you need to mow a 1,300, 2,600, or 5,200 ft² plot (400 m², 800 m², or 1,600 m²). You should also adjust the width of the reach accordingly. With modern garden products, you can choose between 7 and 22 inches (17 and 56 cm). However, you’ll most often find values of around 8 to 10 inches (20 to 25 cm).

Blades

One of the most important elements of a robotic lawnmower is the mower deck. This consists of blades that cut the grass blade at a pre-selected height. There are currently two types of blades on the market:

  • Razor blades
  • Classic blades
Blade typePurposeAdvantagesDisadvantages
Razor bladesRegular trimming of short grass+ Easy to change
+ More widespread
– Short service life
Classic bladesRather for coats and longer grass+ Robust– Must be sharpened
– Fewer products available

Razor blades

As the name suggests, these are small knives the size of a classic razor blade. They’re attached to a rotating disc by a crew, the usual number of these knives is 3 to 4. These are the most common blades on robotic lawnmowers, as they’re suitable for regular cutting of short grass. Their disadvantage is their relatively short service life. You’ll need to replace the blades during the season, but this isn’t difficult.

Classic blades

Classic blades are less common on robotic lawnmowers. You’ll usually find them on conventional lawnmowers. This is a blade made from a single piece of metal that’s sturdy and durable. This gives it a longer life and means it doesn’t need to be replaced as often. However, regular maintenance is unavoidable and the blade needs to be sharpened occasionally. This type of mowing blade is more suitable for cutting coarse and long grass.

Terrain possibilities

You don’t just choose a robotic mower based on the maximum area of grass you expect to cut. You need to look at your garden, or the area where the mower will be working, as a unified workspace. In particular, you should take into account things such as the roughness of the garden.

One important area is the narrow passages. These are the minimum spaces between two obstacles that the robotic lawnmower is able to pass between. This information is nowadays presented in the general parameters of each model and is given in centimeters. The smallest spacing between obstacles is between 35 to 51 inches (90 and 130 cm). The mower simply can’t pass through a narrower space. The machine also moves randomly in passages and changes direction to avoid unsightly paths.

The slope of the terrain

Next is the slope or gradient of the terrain. Most models of robotic mowers have the technical and performance dispositions not only for driving on flat ground but also up slopes. Here too, the sloping specified in the product specifications plays an important role. Looking at the technical specification, you’ll find two boxes that indicate the slope of the terrain.

One, with a higher number, indicates the maximum slope of the terrain inside the working area. This is usually between 15 and 45%. The second box indicates the maximum possible slope near the mowing boundary, i.e. the perimeter cable, and the charging station. In such areas, the permissible slope is usually around 10%.

If your garden is full of all sorts of unevenness and holes, try to fill them in and eliminate them as much as possible to get the most efficient use out of your robotic mower and avoid the inconvenience of overturned or stuck equipment, as well as going through puddles in rainy weather.

Noise

Although a robotic lawnmower is an automatic tool that you may not even notice when cutting the grass, the noise level of such a machine shouldn’t be underestimated. Even though you can program your mowing for a morning when you’re not at home, for example, you certainly don’t want to annoy your neighbors or yourself with several hours of mowing if you’re engaged in other work or leisure activities in the garden. Remember also that when mowing a larger area, the mower may be running for a large part of the day.

Of course, the noise level depends on various parameters such as power, engine processing, etc. Usually, you’ll encounter a noise level of around 60 dB, which corresponds roughly to a noisy conversation.

Controls

Although robotic lawnmowers are sophisticated devices, you certainly don’t have to worry about complicated controls. Each device usually includes a digital LCD display on the top of the machine under a handy cover to prevent damage. You can control the mower using the appropriate number of buttons, depending on how many functions your chosen model will have – START, STOP, cursor keys, and more.

At the beginning of everything you have to set the right mowing zones, which we’ll talk about at the end of our article, and then you don’t have to worry about anything. The most you can do is adjust the operating mode.

In the case of the control, there’s one more option. Some manufacturers equip their mowers with Bluetooth modules. If you want to control your lawnmower from the comfort of your terrace, for example, you just need to download an app to your smartphone. With it, you control your garden tool just like a remote control car. You can change the settings and start the mower at will. However, this isn’t a usual part of every model, so keep an eye out for it if you wish. You’ll hardly come across a separate remote control on robotic lawnmowers.

Functions

There’s certainly no doubt about the timelessness of robotic lawnmowers. These automatic machines are also equipped with a range of practical features that can take your lawn mowing in the garden or anywhere else to a whole new level. Below is a list of features you may encounter when choosing an automatic lawn mower.

  • Sensors of various types – Depending on the specific mode, you’ll get a product equipped with a number of safety sensors. These include sensors that prevent you from hitting an obstacle in the path and sensors that reveal the slope of the ground.
  • Rain sensor – A handy tool when you put the mower out in the garden and it starts to rain while you’re mowing. The mower can assess such a situation on its own and will drive to the charging station.
  • Frost sensor – The moment the temperature approaches freezing, the mower interrupts the planned mowing to avoid damaging the lawn.
  • GPS module – Modern devices have a GPS module, with the help of which you can perfectly plan your mowing route and have your product under complete control. Among other things, the robotic mower with GPS is aware of what area it has already mowed and what it hasn’t.
  • PIN code – Robotic mowers can be equipped with an access code, without which it’s not possible to set any mowing programs or make any changes to them.
  • Alarm – As this is a more expensive piece of gardening equipment left unattended to work for you, an alarm will come in handy. This will usually sound the moment the mower is taken off the ground. For example, if someone tries to steal it.
  • Split mowing zones – You can divide the garden area into several separate zones and only send the mower to one of them at a time. Usually, this feature is combined with an app control in which the zones are separated.

The most popular robotic lawnmower brands

There are several manufacturers of robotic lawnmowers. In this chapter, we’ll introduce you to a few of them.

Husqvarna robotic lawnmowers

Husqvarna robotic mowers are in the higher price category. However, both quality and features match this. There are smaller mowers for areas up to 2,000 ft² (600 m²), but also large models for really large areas up to 16,500 ft² (5,000 m²). In addition to the classic mowers with a perimeter wire, there are also GPS-guided mowers. Owners of sloping land will also be pleased with a model with the ability to work on slopes of up to 70%.

Gardena robotic lawnmowers

The German brand offers a complete range of garden care equipment, including the Sileno range of robotic mowers. These are characterized by their low noise level. There are models with a maximum area of 820 to 4,920 ft² (250 to 1,500 m²). The mowers are equipped with two types of smart technology – Bluetooth and Smart. Depending on your preference, you can then choose which method of operation suits you better. The mowers can also cope with sloping terrain. Depending on the model, a slope of 25 to 35% is allowed.

Price

Robotic lawnmowers represent a higher initial investment in terms of purchase costs, but this has a very early payback. This is mainly in the comfort of mowing the grass, with which you’ll not have any additional worries or physical effort. To give you an idea of how much such a robotic lawn mower will cost you, here’s a basic price breakdown.

The most common brands you’ll come across are Robomow, Husqvarna, Stiga, John Deere, AL-KO, and Worx.

Price up to $1,200

If you want to keep the purchase price of your future robotic lawnmower within $1,200, expect to come across products suitable for mowing smaller lawn areas of around 1,300 to 2,300 ft² (400-700 m²). Of course, the battery life of around 330 to 660 ft² (100-200 m²) per charge will match the price. The cutting range is around 8 to 10 inches (20-25 cm). These are lighter and smaller devices, where you won’t find as many options for adjusting the length of the grass.

Still, such robotic mowers will do their job, they’ll be equipped with a transport handle and even a rain sensor.

Price from $1,200 to $2,000

In this price range, you’ll undoubtedly get much more powerful machines, where you won’t have to worry about a ground slope of around 45 degrees or the recommended maximum lawn size of around 4,921 ft² (1,500 m²). The powerful batteries are capable of fast charging. The higher mowing width of between 10 to 12 inches (25-30 cm) is certainly a nice touch.

As an added bonus, you’ll find, for example, a security code for controlling the automatic mower or a practical alarm against thieves and unwanted tampering.

Price over $2,000

From $2,000 and upwards, you’ll discover the true magic of robotic lawnmowers. You can look forward to a long mowing life on a single charge, which can cover an area of up to 1,000 ft² (300 m²). A garden helper of this type is hardly caught off guard by terrain inclinations of up to 45 degrees and can easily mow a garden of over 6,561 ft² (2,000 m²). This, by the way, is reflected in cutting width of up to 22 inches (56 cm) and infinitely variable cutting height adjustment from 0.6 inches (1.5 cm) and upwards.

These modern robotic lawnmowers can also be controlled using a remote control or a smartphone and a special app.

Correct setting of mowing boundaries

Most robotic lawnmowers work on the very simple principle of defining cutting boundaries. This is achieved with the help of a boundary cable. This is placed on the ground or just a few centimeters below the surface. Special pins are used to secure it. It’s this wire that defines the space in which the robotic mower moves. To make sure you don’t make any mistakes when creating your mowing area, here are some practical tips and insights:

  • Don’t place the charging unit directly in the corner of the plot. The mower needs plenty of room to maneuver and get into the station.
  • The boundary cable must always start and end at the charging station.
  • The boundary cable should be laid at least 5 inches from property lines, fences, and other obstructions. For water areas, holes, and other hazardous locations, place the boundary cable at least 10 to 12 inches (25 to 30 cm) away.
  • The boundary cable must not cross or break at any point. It must always enclose the entire area from point A to point B.
  • If you have obstacles in your garden (trees, rockeries), make an island around them with the boundary wire so that the mower avoids them and doesn’t run into them unnecessarily.
  • A guide wire is used to better direct the robotic lawnmower to the charging station.

Setting the mowing boundaries and installing the robotic mower is quite a challenging procedure. However, the time you spend on it will soon pay you back many times over. You can find many installation videos on the internet to learn everything you need to know. Dealers also often offer an installation service for a fee, so you don’t have to worry about doing something wrong and the mower not cutting properly.

Maintenance

Even though robotic lawnmowers are automatic machines that you don’t have to do any work to operate, regular maintenance is easy to avoid, just like with other similar equipment. At repeated intervals, you should check several important parts of this mechanical helper.

The mower deck

Even though robotic mowers only trim and maintain already low grass, pieces of grass still accumulate in these areas of the mower. These need to be removed regularly in order for the mower to reach its maximum potential and cutting performance. Never clean the mower with water. Simply sweep the mower deck area, for example with a stick or by hand using a glove.

Don’t forget to sharpen the blades. Their service life depends on the material used but also on other circumstances. For example, if you have stones, fallen fruit or nuts in your garden, the blades can quickly become dull. Razor blades in particular are easy to replace, even after one piece. You’ll usually receive a spare set in the package with the mower, or you can buy them separately.

Wheels

Check these parts of the mower from time to time. The wheels may also need lubrication. They require checking because a lot of unwanted things from the garden can get tangled in the wheels, including the perimeter wire that robotic mowers use to navigate the space.

Frequently asked questions about robotic lawnmowers

Which robotic lawnmower should I choose?

The first thing you need to consider when choosing is the size of the garden, mowers categorized by area makes into several categories. The area determines the battery capacity, the reach, and the overall size of the mower. If you have a typical garden with many obstacles or divided into different zones, or very sloping, choose a model that can handle the specifics.

How does the mower orient itself in space?

The boundaries of the mowing area are demarcated with a special wire. The mower won’t cross this wire and so, for example, won’t drive into flower beds. The mower is also equipped with a number of sensors. In the event of lifting or tilting, the blade stops to prevent injury or damage.

Does the robotic lawnmower have a collection basket?

The robotic mower doesn’t collect the grass clippings but spreads them evenly over the lawn. This process is called mulching and is good for the lawn. Several millimeters of grass add nutrients to the lawn and fertilize it.

How long do robotic lawnmowers last?

Robotic lawnmowers operate for battery life, which can range from 60 to 300 minutes depending on the model. The mower will drive itself to a charging station when the battery is low and will start mowing again if it’s set to do so.

Leave a Comment