Robot vacuum cleaner purchasing advice: how to choose the right product

  • What you need to know
  • Robot vacuum cleaners not only relieve their users of some of the housework, but thanks to their compact size they can also reach areas that a conventional vacuum cleaner cannot reach.
  • Equipped with a timer function, the electronic cleaning aids can be programmed to start the cleaning process automatically at a later time, for example when you are not at home.
  • Depending on the driving strategy, vacuum robots move either unsystematically, i.e. chaotically, or systematically, i.e. according to a certain pattern.
  • Via infrared, ultrasonic, or laser sensors, the autonomous household aids recognize whether they are approaching an obstacle or a precipice and change their direction of travel if necessary.
  • To ensure that the device does not run out of battery in the middle of the process or is ready for use again as quickly as possible, a model with a long battery life combined with a short charging time is recommended.
  • Practical extras such as an additional mopping function, control via app, or voice command as well as special brushes and attachments for pet hair provide additional comfort.
robot vacuum cleaner comparison

The autonomous household helpers

For many, housework is a chore that is gladly put off. Vacuuming, in particular, is one of the tasks that has to be done almost daily, as a layer of dust on the floor is unpleasant not only for aesthetic but also for health reasons. Due to time constraints, however, this is hardly possible in everyday life. Moreover, vacuuming is not only time-consuming but also energy-sapping — especially after a hard day’s work.

The self-propelled vacuum cleaners conveniently do the job themselves and, on top of that, get into hard-to-reach places such as under the bed, the couch, or cupboards. Robot vacuum cleaners are particularly recommended for people who hardly find time for housework in their hectic working day. People with physical ailments who are no longer able to vacuum will also appreciate the autonomous cleaning aids.

House dust – what is it?

The more people live in a household, the more dust is produced. Dust is not only a waste product of fibers, but also consists of organic particles such as dead skin flakes, animal and human hair, and fungal spores. Carpets in particular form an ideal hearth in which germs and bacteria multiply, which can trigger allergies such as skin irritations. To avoid this, it is important to remove dust regularly.

dust components
The different components of house dust.

George – the forefather of the robot vacuum cleaner

Robot vacuum cleaners are by no means a 21st century invention. The first household robot that could vacuum on its own was developed as early as 1949 by the British Tony Sale. George, as he called him, with his antenna and glowing eyes, however, hardly resembled the models we know today. In 1978, Nintendo created a robot vacuum cleaner called Chiritorie, which had a remote control, a rotating axle, and a collection bin. Although it was much easier to handle, it was also very wobbly. Seven years later, the Dustbot appeared on the market, the first robot vacuum cleaner with a built-in vacuum that could even suck up crumbs and small pieces of paper. Over time, the robot vacuum cleaners not only became smaller and more sophisticated, but also cheaper. Today, the practical household aids are no longer available for several thousand dollars, but for as little as $200.

The miniature cleaning maniac for little money?

Since robot vacuum cleaners are nevertheless considerably more expensive than ordinary vacuum cleaners, many consumers wonder whether such an expensive purchase is really worth it. However, they don’t have to spend a fortune on a solid robot vacuum cleaner. The cost factor relates not only to the suction power, but most importantly to the range of functions of the device. There are now models in various price categories, so there is something for every budget. The cheapest devices start at around $50, the most expensive ones cost around $1000.

Price rangeFurnishing
$50 to $200Cheap devices mainly cope with smooth floors, have low battery runtimes, and their room recognition is not very sophisticated.
$200 to $500Medium-priced devices are suitable for different types of floors, are equipped with programming functions, and offer a longer battery life with a comparatively high suction power.
$500 to $1000Expensive devices are equipped with high-tech functions, work with high wattages and long battery life, and are also suitable for large rooms of over 1000 square feet.
Vacuum robots and their equipment divided into three price categories.

The advantages

A robot vacuum cleaner is usually a flat, cylindrical household appliance with a diameter of about 12 inches and a height of around 4 inches. This design allows them to reach hard-to-reach places, such as under sofas and closets. Depending on the navigation technique, the vacuum cleans up to 850 square feet in a single pass.

If the device has a timer function, the user has the option of having the suction process start automatically at a later time, for example when he or she is not at home. On its vacuuming tour, it not only avoids obstacles, but even overcomes carpet edges and detects stairs or higher landings in time to avoid a fall. Since the self-sufficient household aid is battery-powered, it must be recharged afterwards. After the vacuuming round, the robot returns to its charging station and only resumes its work when the battery is fully charged — ideally at the point where it previously had to stop due to declining battery power. The user therefore only has to worry about emptying the dust container regularly. Robot vacuum cleaners don’t need bags at all.

The typical design of a robot vacuum cleaner

The decision as to whether the robot vacuum cleaner should be square or round is primarily a question of aesthetics. For most consumers, a round shape looks more modern and generally more positive than an angular design, which is often perceived as colder. Some manufacturers also design the housing playfully so that the robot vacuum cleaner becomes a visual highlight: for example, there is a robot vacuum cleaner in Darth Vader design that has sound effects such as the typical rattle or hiss of a lightsaber and plays the Imperial March.

In terms of their basic design, however, most models are similar: on the top is the dust container lid, under which is the collection box, an LC display with controls, and a bumper with the obstacle sensor. On the sides are the exhaust vents and the main power switch. On the bottom of the unit are the charging contacts with the fall sensors, the wheels, and the brushes.

The pros and cons of an autonomous vacuum cleaner

Both autonomous and effective, robotic vacuum cleaners make household chores easier for consumers and save a considerable amount of time. In addition, they reach places that are difficult or impossible to reach with a conventional vacuum cleaner. Their back-friendly handling is not only optimal for older people, but also for all those who reach for the vacuum cleaner every day. Robot vacuum cleaners are also excellent for allergy sufferers: most models have a HEPA filter that thoroughly removes not only dust and pollen but also animal hair. Another advantage of the small machines that should not be underestimated is that they are much quieter than their larger competitors.

HEPA filters — cleaning at a high level

High-efficiency particulate air filters are so-called HEPA filters. They consist of several thin layers made of synthetic materials such as cellulose or glass fibers. Their close-meshed fibre network filters even the smallest particles effectively, so that they remove over 99.9% of all particles from the air.

However, if the path of the vacuum cleaner robots is blocked, depending on the programming, an error message may be generated so that they abort the cleaning process. The natural enemies of robot vacuum cleaners include deep pile carpets, corners, cables, reflective surfaces, and fragile objects such as vases. While low pile carpets are usually not a problem, there is a risk with deep pile variants that the brushes get caught in the pile layer. Another shortcoming is the comparatively small dust container, which users have to empty frequently. In addition, the autonomous household aids are also considerably more expensive than conventional vacuum cleaners.

However, if a few basic requirements are met, a solid model can serve as a worthy replacement for the ordinary vacuum cleaner:

  • Floors should be mainly smooth coverings such as tile or hardwood floors.
  • Carpets should not be higher than an inch and should not have fringes.
  • The rooms should not be too angled or cluttered with furniture.


  • Works independently
  • Great time saving
  • Cleans even hard to reach places
  • Comparatively quiet in operation
  • Suitable for allergy sufferers
  • Back-friendly


  • Weaker suction power
  • Poorer cleaning of corners and edges
  • Not suitable for deep pile
  • Relatively small dust container
  • Higher purchase costs

Brushes, sensors, and time control

The exact way a robot vacuum cleaner works varies depending on the manufacturer and model. However, they are all the same in one way: they move independently in the room. To do this, they are equipped with two wheels. Thanks to the suspension, they ensure that the device overcomes doorsteps and other small obstacles with ease. The steering wheel, which is located on the front, navigates the vacuum cleaner in any direction through the room. With the help of this wheel combination, the robot is very mobile and can even reach areas that are difficult to access.

On the underside of the device are counter-rotating brushes that first loosen the dirt and then transport the particles under the housing. There, the robot sucks in the dirty air and brings it through an opening into the interior of the vacuum cleaner, where there is a dust container that collects the dirt. Models with side brushes clean corners and edges even more thoroughly from dirt and dust particles. After the cleaning process, users empty the collection bin manually.

To enable the vacuum cleaner to detect larger obstacles, it is equipped with sensors. These are transmitters that inform the robot about the area to be vacuumed. The navigation system ensures on the one hand that the device cleans every surface in the room and on the other that it avoids crashes or collisions with furniture, walls, or toys. The collision sensor ensures that the robot vacuum changes its direction as soon as it bumps into an obstacle. Modern devices are equipped with infrared, ultrasonic, or laser sensors, thanks to which the robot vacuum cleaner recognizes an object that is in the way in good time and drives around it. The fall sensor registers steps and other precipices, and it prevents the robot from falling down.

Ready for anything: the different cleaning modes

Depending on the surface, the degree of dirt, and the structure of the room, different cleaning principles are suitable. The latest robot vacuum cleaners are therefore equipped with a variety of modes to be prepared for any situation:

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Carpet mode

Thanks to built-in sensors, modern vacuum robots recognize whether the surface is a smooth hard floor or a carpet and adjust the cleaning process accordingly. If it is a carpet, the smart device automatically switches to carpet mode. For example, they change the speed of the brushes on carpeted floors and increase the suction power at the same time. On smooth floors, they save more battery life.

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Turbo mode

By switching on the so-called turbo mode, also called “max power”, the robot vacuum cleaner obtains a significantly higher suction power; this means that the rotation speed of the main brush increases.

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Edge mode

In Edge mode, the cleaning of corners and edges is particularly thorough thanks to the side brushes.

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Intensive mode

The special cleaning mode is switched on either manually or automatically for particularly dirty areas. Often there are additional sensors inside the device that check visually or acoustically how dirty the floor is. Acoustically, for example, this works by detecting the noise that coarse dirt makes when it is spun around in the collection container. Visually, a light barrier identifies the dirt particles. The robot vacuum cleans the corresponding areas more intensively, for example by running over them several times.

The driving strategies

With regard to the navigation system, there are two types of robot vacuum cleaners: devices that work according to a systematic cleaning principle and those that drive over areas chaotically. The latter are significantly cheaper.

Chance as the deciding factor: the unsystematic driving strategy

The most widespread robotic vacuum cleaners are still those with a non-systematic cleaning principle, because they are particularly cheap to buy. In this context, unsystematic means that the robot vacuum cleaner vacuums without a predefined pattern and finds its way solely on the basis of the contact sensors. This random principle, which is also called zigzag mode, often leads to some areas not being cleaned at all or being cleaned several times. As soon as the cleaning helpers come across an obstacle, be it a closet or a decorative item, they change direction and drive straight ahead again until they bump into something — or until their battery is empty. While this method is more likely to remove tough dirt residues, users often still have to do it themselves to get a consistent result. The time factor also plays a decisive role here: the longer the process takes, the more likely it is that every spot will actually be cleaned.

A kind of bumper is attached to the robot, which triggers one of the usually three micro-switches when it comes into contact with an obstacle and turns to the left, right, or back accordingly. Robots with such touch sensors therefore constantly collide with furniture or walls, but they are designed in such a way that neither the objects nor the robots themselves are damaged. If, for example, the right edge of the appliance bumps into something, it first tries to move to the right. If it does not succeed, it turns away at the same angle until it can continue the cleaning process.

robot strategies
If a robot vacuum cleaner with an unsystematic driving strategy encounters an obstacle, it makes a turn.

In the unsystematic approach, a distinction is made between the amoeba strategy and the random strategy, which are very similar, at least in terms of their haphazard driving style. With the amoeba strategy, the robots travel as long as possible in a straight line and, in the event of a collision reported to them by contact sensors, change their direction of travel so that they again travel a long straight line. A random strategy device, on the other hand, randomly interrupts straight travel and selects its new direction of travel according to the random principle. Vacuum robots that work according to the random principle miss less than their amoeba counterparts and are correspondingly more efficient than the amoeba strategy, but in labyrinthine or tightly furnished rooms it oocurs more often with both driving methods that the robots get stuck.

Following a certain pattern: the systematic driving strategy

Since purely random drives might miss one or two spots or drive over the same ones twice, thus they are not very efficient. Driving according to a plan makes more sense because the area to be cleaned is mapped in advance with a camera or laser and then driven over according to a certain pattern, for example in a spiral. Systematic vacuum cleaner robots are therefore more intelligent and have more complex sensors that analyze their surroundings in order to brake and change direction in time if necessary. To calculate distances, manufacturers now use sophisticated infrared or ultrasonic sensors as well as laser technologies. Since the robot knows the exact distance, collisions no longer occur in the ideal case. Instead, it stops and changes direction. To compensate for the disadvantages of the different sensors, several technologies are often used. Infrared sensors have problems with deep black objects because they reflect the measurement signal and are therefore overlooked. Ultrasonic sensors, on the other hand, struggle with narrow objects that reflect the sound differently.

wall tracking icon
Measuring by wall tracking

As a rule, all modern robot vacuum cleaners have mastered the strategy of wall tracking. They first try to drive along the walls of a room — on the one hand to clean this area, and on the other hand to measure the room. Any furniture standing against the wall is circumnavigated. The rotating side brushes are also helpful here, as they pick up dirt from around the edges.

spiral drive icon
On spot: the spiral drive

Another strategy of modern robot vacuum cleaners is the spiral mode, also known as spot mode, in which the device travels a certain distance from a center point to the outside or vice versa in a spiral. This mode is used for larger open spaces or large areas of dirt in a certain place, as the tracks overlap slightly and in this way clean an area in a precise manner.

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Room mapping via camera

Some manufacturers rely on built-in cameras on the top of the device that scan the room and then create a kind of map. They register the positions or sizes of the furniture and divide the room into individual segments. With the help of room mapping, i.e. room recognition, the robots can clean the room in a planned, speedy, and particularly efficient manner, lane by lane.

Virtual walls thanks to lighthouse technology

A special feature is the so-called lighthouse technology, with which users can make certain zones within a room inaccessible to the vacuuming robot, for example, for safety reasons. This usually involves a hand-sized plastic cylinder that emits infrared rays and is switched on at the touch of a button. If a lighthouse, i.e. the virtual barrier, is placed at a location, the device cannot enter this area. As soon as the robot starts moving, this virtual wall is activated.

For example, users can use it to block door thresholds so that the robot vacuum cleaner only cleans the desired room. This technology is also advantageous when consumers want to separate certain objects, such as their pet’s water bowl or the floor vase, so that no water is spilled or the fragile object is damaged. In addition, an entire work area, for example the desk at which one is currently sitting, or the area around the dog basket in which the four-legged friend is sleeping, can also be excluded.

lighthouse tech icon
With the help of lighthouse technology, users demarcate areas.

Which strategy is the right one?

As a rule of thumb, the more sensors attached to the robot vacuum cleaner, the more effective its mode of operation. If there is a lot of deep black furniture near the floor, infrared sensors are not enough. If there are stairs in your home, it is also recommended that the robot vacuum cleaner is equipped with a fall sensor. While in large rooms with little furniture a planned, parallel driving strategy is ideal, in packed rooms where chairs, sofas, and other objects make navigation difficult, a random strategy is more suitable.

The purchase criteria

Due to the different features that robot vacuum cleaners bring with them, many consumers find it difficult to make a purchase decision. So what is important when buying a robot vacuum cleaner?

height icon


Basically, all robot vacuum cleaners are characterized by a low height. Depending on the model, it ranges from three to four inches. The lower the height, the more likely they are to reach under beds, sofas, and cupboards that an ordinary vacuum cleaner would not reach. Therefore, it is important to measure the distances between the floor and furniture before buying. However, higher-built robot vacuum cleaners also have their advantages, because they can more easily overcome small steps and carpets.

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The capacity of the dust box is also related to the height, because the higher the robot is, the larger the dust box usually is. The volume usually varies between 7 and 27 ounces. The larger and dirtier the area, the faster the box fills up. Since a box with a capacity of 7 ounces has to be emptied correspondingly often, in many cases it is more advisable to choose a size between 17 and 20 ounces. However, this depends not only on the size of the area to be cleaned, but also on other circumstances, such as whether there are pets or children in the household who cause more dirt.

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The suction power

The wattage of a robot vacuum cleaner is usually in the double-digit range. Unlike its big competitors, which work with over 1,000W, a high output power is not necessary here to achieve a satisfactory cleaning performance. More wattage does not necessarily mean more suction power, but above all higher power consumption. Robots with 40W often vacuum just as efficiently as a conventional vacuum cleaner with a much higher output. The reason: unlike standard vacuum cleaners, the robot does not have to transport the vacuumed material over a long tube into the dust container.

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The noise level

Although the small household aids are not completely silent, their noise level of 50 to 70 dB is lower than that of a conventional vacuum cleaner, which reaches an average of 70 to 80 dB. For comparison: the normal volume of a radio or television is about 60 dB. Thus, the robot vacuum cleaner could possibly disturb the movie night. Therefore, good devices are equipped with a timer function that allows the user to start the vacuuming process when they are not at home.

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The filter

Since it is no use for the robot vacuum cleaner to capture the dust and then blow the fine dust back into the air, all modern models have a so-called HEPA filter (High Efficiency Particulate Airfilter). These filter pollen, asbestos, mites, suspended particles, bacteria, and viruses from the air sucked in before it is blown out again, which is why allergy sufferers in particular get their money’s worth.

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Battery life

Unlike their big competitors, robot vacuum cleaners come with a battery rather than a cord. Most models are designed so that their battery lasts at least 45 minutes before it needs to be recharged. A few modern robot vacuum cleaners can even manage 1.5 to 2 hours. Conveniently, most models have a display that informs the user of the current battery level. When the battery is running low, the robot automatically drives to its charging station. In general, a robot vacuum cleaner should be able to clean an area of about 200 square feet in 60 to 80 minutes, i.e. on one battery charge. The larger the area, the more powerful the battery should be. A model with several batteries is recommended for large areas. In rooms with many corners or obstacles, the cleaning process will naturally take longer.

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The charging time

Just like the battery life, the charging time varies from manufacturer to manufacturer. The range is from one hour to five hours. Most robot vacuum cleaners, however, need a relatively long time, namely three to five hours on average. In return, they drive back to their charging station independently and only continue their work when they are fully charged. So if you want to use your robot vacuum cleaner more spontaneously, you should buy a model with a short charging time, i.e. between one and three hours.

NiMH or Li-Ion: which battery is the best?

When buying a robot vacuum cleaner, customers decide between a NiMH and a Li-Ion battery. It is true that nickel-metal hydride batteries are better than their predecessors, the nickel-cadmium batteries, in that they are not subject to memory effect and have a higher energy density. However, at 0.28 megajoules per kilogram, their energy density is still lower than that of a lithium-ion battery at 0.65 megajoules per kilogram. This means that the latter not only survives twice as many charging cycles (500 to 800) as a NiMH battery (350 to 500), but also lives much longer, 2.7 to 4.4 years instead of only 2.0 to 2.7 years.

Practical extras

There are significant differences in the equipment and scope of delivery. While the range of functions is very limited in some devices, some high-priced models are equipped with numerous additional features. But which extras are actually worth it?

Timer-controlled: the timer function

Although the robot usually starts from its charging station on a timer and also returns to it independently, consumers have to carry the device to other floors (usually between 3 and 9 lb) because it cannot climb stairs. The timer function allows users to use the device at any time, as they can set when and for how long the cleaning should take place. For larger areas, the so-called multi-room function is also recommended, which ensures that the robot vacuum cleaner continues its work after charging exactly where it left off before.

Docking, charging, emptying: the charging station

Before buying a robot vacuum cleaner, consumers should find out whether the charging station is included in the scope of delivery. As soon as the battery life comes to an end, the system signals the robot to stop the cleaning process and head for the charging station. It finds its way there by following an infrared beam. With the help of its 360-degree sensor, the robot vacuum cleaner locates the signal from every direction. Once it has located the signal, it immediately heads for the charging station to dock there. If the charging contacts are on the rear side, the device turns around to park in the right direction.

State-of-the-art appliances have already reached the point where they automatically empty their dust bin at the charging station, making them even more self-sufficient and relieving the user of another manual step.

Convenient control via remote control and app

With the help of a remote control, users can conveniently control their robot vacuum cleaner from a distance, for example to get it out from under the bed or to set the timer. Ideally, the cleaning modes can also be selected via the remote control. A remote control is also practical if, for example, crumbs fall on the floor while eating and you want to call the device to you. Robot vacuum cleaners with a Wi-Fi connection go one step further, because they can be controlled via an app. In this way, users can start their device while on the move. In addition, they can control the work of the device via the app: it shows whether it has already carried out all activities, whether cleaning has been completed successfully or whether it may have got stuck on an obstacle. With a smart home connection, for example via the virtual assistant Alexa, some robot vacuum cleaners can be voice-operated. Nevertheless, it is better if the model also has buttons in case the Wi-Fi connection is interrupted.

The hybrid robot: a combination of mopping and vacuuming function

Some vacuum robots are also equipped with a mopping function so that they not only vacuum dirt but also mop the floor. Since such devices combine two operations in one, this additional equipment is particularly recommended for households with floors that require regular mopping. However, the function is not suitable for carpeted floors, but only for hard floors such as tiles, parquet, and laminate. While inexpensive models use detachable wet wipes that don’t mop very efficiently, higher-priced units have a combined water and dust container. The water tank consists of a split tank that separates the clean water from the dirty water.

robot vac mopping
Robot vacuum cleaners with integrated mopping function combine the advantages of a vacuum cleaner with those of a mopping robot.

Optimized for pet hair

Since in households with pets there is a risk that the pet hair will wrap around the brushes and block them, there are special vacuum robots that are equipped with rubber rollers. These easily transport the pet hair inside the vacuum cleaner. Other robot vacuum cleaners are equipped with special brushes that remove pet hair from carpets and floors more efficiently. Ideally, several attachments and suction devices for different areas of application are included in the scope of delivery.

Climbing hurdles with an all-wheel drive and climbing assistance

Since doorsteps and carpets are often insurmountable obstacles for the small robots, some models have so-called climbing aids attached to the drive wheels. In addition, they have all-wheel drive so that they can easily bridge a height difference of up to an inch.

Practical cleaning tips

Although a robot vacuum cleaner takes a lot of work off the user’s hands, don’t forget that it also needs cleaning from time to time. Only those who maintain their robots regularly will benefit from them in the long term. There is more to it than just emptying the dust container, namely cleaning

  • the main brush: since the main brush is the first to come into contact with the dirty floor, a lot of dirt, dust, and hair collects here. Before the user cleans the brush with lukewarm water and the cleaning tool included in the delivery, coarse dirt such as hair should be removed from the bristles by hand,
  • the side brushes: since a lot of dirt also accumulates in the thread, it is recommended to remove the screws and take the brushes out of the holder. Once the dirt in the thread has been removed, the next step is to remove the hair and crumbs that are stuck to the brushes. Once the coarse dirt is removed, users hold the brushes under warm water to remove the fine dust as well,
  • the wheels: dirt accumulates especially in the wheel housings. This should be removed regularly to ensure that the appliance runs smoothly,
  • the dust container: it is best for users to open the dust container directly above the trash can, as dirt could fall out. Not only should you empty it regularly so that it can continue to collect dust, but you should also clean it with a brush so that it doesn’t become too dusty. Hot water can also be used to remove germs. Afterwards, users should dry it thoroughly before using it again,
  • the sensors: users should only clean the sensitive sensors very carefully with a microfiber cloth. Chemical or alcohol-based cleaning agents are not recommended, as they could damage the sensors,
  • the filter: if the filter is washable, you can save yourself a replacement or two. To clean it, simply hold it under running water and then let it dry,
  • the suction opening: the suction opening, from where the dust falls into the dust container, is often neglected, but it also needs regular cleaning, as dirt also accumulates here,
  • and the surface: to remove dirt deposits on the surface of the appliance, a damp cloth with which users wipe the top, bottom, and sides is sufficient.

In addition to cleaning, it is also important to check whether the battery needs to be replaced. After a certain time (usually two to four years), it becomes less effective or, in the worst case, defective. To replace it, users turn the vacuum cleaner upside down, open the lid, remove the battery and insert the replacement battery. The old battery should then not be disposed of in the residual waste, but according to local or state laws. Often home improvement centers or office supply stores offer collection boxes by organizations like Earth911.

Images 1-19: © FinalCheck