HOBOT-388 Window Cleaning Robot is a Smarter Way to Clean Your Windows

Readers of my articles are probably aware that I’m a fan of robots that help with housework. But, it is important to remember that robots that help with chores around a home are nothing new. The electric clothes washer was introduced in 1908, the electric clothes dryer was introduced in 1938, and an electric powered dishwasher was introduced in 1929. Usage of these devices has become so widespread that people don’t think of them as robots doing their housework, but the reality is that they are.

In the past, I’ve written about robot lawn mowers, the Tertill robot that weeds your garden, and shortly there will be an article on the integration of robot vacuums and mops into the smart home.

Another household chore that is both tedious and potentially dangerous, is washing your home’s windows. According to an article published by the International Association of Certified Home Inspectors, “Each year, there are more than 164,000 emergency room-treated injuries and 300 deaths in the U.S. that are caused by falls from ladders. Most ladder deaths are from falls of 10 feet or less.”

You could hire someone to wash your windows, of course, but that can be expensive. According to HomeGuide, a professional window washer charges about $258 to clean the windows in a 1,500-square-foot house. With that price in mind, the purchase of a robot to help clean your windows is a reasonable alternative that can quickly pay for itself.

HOBOT was established in 2010 by a group of technology specialists and is now focused on the development of home robots. They currently offer a line of robotic vacuums/mops and nine different models of robotic window cleaners. HOBOT provided me with one of their HOBOT-388 window cleaners to evaluate for this article.

Early robotic window cleaners used magnets to hold themselves against the glass of a window. A magnet placed on one side of a window was attracted to a magnet in the robot operating on the other side of the window. The attraction between the two magnets kept the robot adhered tightly to the window. Today, most robotic window cleaners use motors that create a vacuum to hold the robot against the glass.

How the HOBOT-388 Works

The HOBOT-388 uses a high-efficiency brushless DC motor to provide the suction to hold the robot to the glass and to vacuum a large amount of the dust off of a window.

HOBOT says that HOBOT-388 vacuum system is so strong that it allows it to overcome small leaks and that it can even clean some slightly uneven surfaces, such as bathroom tiles; smooth stone, such as polished marble and granite; and some textured glass used for privacy in, for example, bathroom windows and shower surrounds.

It is important to know, however, that the HOBOT-388 is not designed to be used on frameless surfaces where it won’t be able to judge where the edge of the surface. The HOBOT-388 also should not be used on glass that is cracked.

The HOBOT-388 is powered by a plug-in power supply that securely connects to the robot with a 16-foot power cable that screws into the robot. This screw connection ensures there is no chance of the power cable being pulled loose from the robot during operation. In addition, should a power failure occur while the HOBOT-388 is cleaning a window, a built-in battery backup provides up to 20 minutes of reserve power, allowing plenty of time to retrieve the robot.

For additional safety, and to protect the HOBOT-388 in the event that the robot becomes detached from the window, there is a safety rope that can withstand up to 200KG of force.

Controlling the HOBOT-388 is very simple. A user has several different options, including the Start Cleaning button on the robot, the supplied remote control, and a smart phone app (both iOS and Android)

Unlike other window cleaning robots that require you to spray large amounts of cleaning solution on the pads before operating the robot, the HOBOT-388 has a reservoir with an ultrasonic spray head that applies a uniform, mist of solution to the window as the robot moves. In this way the cleaning solution is applied evenly to the window being cleaned instead of the cleaning pads being saturated with cleaning solution when the robot first starts cleaning a window and drying out over the course of the cleaning process. It makes the HOBOT-388 much more efficient at cleaning large windows.

When you are done cleaning your windows, the reservoir should be emptied before the robot is put away. In addition, if you were using a cleaning solution, it is a good idea to put some water in the reservoir and use the spray button on the remote control, or smart phone app, to flush the ultrasonic spray head. This will make sure that there isn’t any fluid remaining in the spray head that could dry and clog it. It should also be noted that you shouldn’t touch the ultrasonic spray head with your fingers, as the oils on your skin could also clog the spray head. Should the spray head become clogged, it is easily replaced.

Hands-on with the HOBOT-388

Inside the box is:

1. Quick start guide
2. User Manual – The user manual included with the HOBOT-388 is short but very detailed and thorough. It even specifies the knot that should be used to connect the safety rope to the robot to assure that it won’t come loose in a fall. It also includes a detailed Frequently Asked Questions (FAQ) section that outlines solutions to common window cleaning problems.
3. Spare set of cleaning rings
4. Safety rope
5. Bottle of HOBOT window detergent
6. Twelve microfiber cleaning pads
7. Infrared (IR) remote control
8. Power adapter and power extension cable
9. Replacement ultrasonic spray nozzle
10. HOBOT-388 robotic window cleaner

Before the HOBOT-388 is used, the internal UPS battery needs to be charged. A small LED on the device’s start cleaning button initially glows yellow. Once the battery is charged, it will glow green.

When you are ready to start cleaning your windows, the first step is to install the cleaning pads. This is very simple to do. First, snap the two cleaning rings from the base of the HOBOT-388. Next, stretch a microfiber cleaning pad across each cleaning ring. Finally, snap the cleaning rings back onto the base of the robot.

After use, the cleaning pads can simply be put into your clothes washer with a load of laundry. However, to maximize the life of the cleaning pads, it is recommended that you use cold water and don’t put them in the dryer.

HOBOT recommends that you only use their Window Cleaning Detergent or water in the HOBOT-388. They only recommend their cleaning solution because they have not tested other solutions with the HOBOT-388. HOBOT Window Cleaning Detergent costs $10 for a 220ml bottle (about 7.5 oz.). The good news is that the HOBOT-388 only uses 1.4ml of detergent to clean a 1 square meter window, so a bottle will last a reasonable amount of time. HOBOT told me that just using water will do a good job cleaning most windows but that their Window Cleaning Detergent will be needed if there is grease on the windows.

Given the price of the HOBOT Window Cleaning Detergent, you may be tempted to use other window cleaning solutions. It is important that the cleaning solution you choose is water based and does not include acids that, over time, could damage the robot. A common practice on the internet is to create your own glass cleaner using vinegar; which contains acetic acid. Cleaning solutions that contain acetic acid should not be used with the HOBOT-388.

I studied the ingredients of HOBOT’s Window Detergent and compared it to the ingredients of several other common window cleaning solutions. I did not find a match, but I don’t claim to be a chemical engineer that understands the attributes of all the chemicals in cleaning solutions and whether one could be an equivalent substitute for another.

If you do use a cleaning solution in your HOBOT-388, you will need to flush the robot’s reservoir and spray head with water before storage to minimize the chance of the spray head becoming clogged. When you are finished cleaning your windows, you’ll need to:

1. Empty any remaining window detergent from the reservoir
2. Fill the reservoir with water
3. Use the remote control, or app, to manually spray the water through the spray head to clear it of cleaning fluid.
4. Empty the water from the reservoir.

Given the above, it is more economically and environmentally sound to put the cleaning fluid back into the bottle using a small funnel rather than pouring it down the drain.

The included remote control is very easy to operate. Because it uses infrared light to transmit commands to the robot, you will need to point it at the robot for it to operate.

On the remote, there are three Auto Cleaning buttons that direct the robot to clean a window. Each contains a directional arrow symbol followed by two linked circles. The Auto Cleaning button with the up-arrow symbol commands the robot to travel up to the top of the window and begin the cleaning process. The other two Auto Cleaning buttons have directional arrow symbols that point left and right. Pressing one of these buttons directs the robot to move in the direction of the arrow and then proceed to clean the area of the window below its current position.

In the upper left corner of the remote is a button with a water droplet symbol. This toggles on/off whether the robot will spray cleaning liquid onto the surface of the glass while cleaning. By default, the use of cleaning fluid is turned on when you start the robot. If you have an especially dirty window HOBOT recommends cleaning the window twice. The first cleaning cycle is done without fluid and the HOBOT-388 will simply vacuum the excess dirt from the surface of the glass. Then replace the pads with a fresh set and perform a second cleaning cycle with fluid. This is only necessary on very dirty windows.

Next on the remote control you will see the typical up-down-left-right ring of buttons with a central OK button found on many remote controls for audio/video equipment. In this case, these buttons can be used to manually move the robot around a window. Pressing an arrow button starts the robot moving in that direction and either pressing the OK button or the stop button (see below) will stop it.

Below those buttons is a manual spray button. This can be used to apply extra cleaning fluid to a particularly dirty location on a window. Finally, there is a stop button and a button labeled “2X” that instructs the robot to make two passes cleaning the window.

The smart phone apps include the exact same controls as the remote for controlling the HOBOT-388, though the buttons are laid out slightly differently. It is important to understand that the robot connects to your smart phone using Bluetooth, so range is somewhat limited.

Setup of the smart phone app and linking your smart phone to the HOBOT-388 is very simple. Once you have downloaded the app, you will need to give permissions for the app to communicate using your smart device’s Bluetooth radio and to send you notifications. With the app installed and running, as soon as you turn on the robot’s power switch, it will automatically connect to the app.

The smart phone app provides notifications including notification if the robot gets into trouble and notification when the robot finishes cleaning a window. Unfortunately, there isn’t a notification when the cleaning reservoir is empty and needs to be refilled. Fortunately, the reservoir is made of clear plastic, so it is easy to see the level of the fluid. However, a sensor to track the fluid and provide a warning when it gets low would be a nice enhancement.

Cleaning a window with the HOBOT-388 is a simple process

1. If this is the first window you are going to clean and the pads are dry, place a little cleaning solution, or water, on the pads. This improves the vacuum’s ability to initially hold the HOBOT-388 tightly to the window.
2. Turn on the power switch. This turns on the motor that drives the fan which creates the vacuum to keep the robot firmly attached to the window.
3. Place the robot on the window
4. Press the Auto Cleaning button on the robot, remote control, or smart app to start the robot cleaning the window.
5. While the robot is cleaning, the LED on the robot turns either blue or white depending on whether it is cleaning with cleaning fluid/water spray, or not. A complete list of the different modes for the indicator LED are listed in the user manual
6. When the robot is done cleaning, it will stop and play a sequence of beeps. To remove the robot from the window, HOBOT recommends that, for safety, you pull the robot away from the glass and then turn the power switch to Off. I personally found that this placed a strain on the window glass due to the strength of the vacuum system in the HOBOT-388. I have concerns that this could damage the seals in double, or triple, glazed windows over time. I found that simply holding the robot in one hand and turning the power switch off with your other hand seemed to provide adequate safety without the risk of damaging the seal in the window. Again, though, this is not the technique recommended by HOBOT.

The HOBOT-388 produces around the same amount of noise (70 decibels at a distance of 1 meter from the robot) as a vacuum. This amount of noise isn’t painful, but it can be somewhat annoying. I would suggest using noise canceling headphones when using the HOBOT-388. But, if you aren’t carrying your phone with you to see the notification when the robot is done cleaning your window, you won’t hear the audible notification made by the robot.

There are some window cleaning robots on the market that are advertised as battery powered, which eliminates the need for a power cable. Personally, I found that plugging the robot in with a long power cable is preferable to a robotic window cleaner that needs to be recharged. Unlike a robotic vacuum/mop, using a robotic window cleaner is an interactive process. Having to periodically stop and recharge a window cleaning robot would simply extend the time it takes to clean all your windows. In addition, if you were distracted by, for example, a phone call while cleaning windows, the battery could run out, and the robot would fall from the window.

Cleaning Performance of the HOBOT-388

First, I want to say that I was surprised at how strong the vacuum system was and how well it held the HOBOT-388 to a window. I had significant concerns that the robot could easily be dislodged from a window, fall to the ground, and be broken. After trying to pull the robot away from a window when it was turned on I felt much more assured that an investment in purchasing a HOBOT-388 wouldn’t be easily lost due to a fall.

I was also impressed with the cleaning performance of the HOBOT-388. My windows hadn’t been cleaned in quite some time. I tried cleaning a few with only a single pass, using just water, and the robot did a very good job of removing the dirt. Even just using water the robot didn’t leave any streaks.

It is important to note that the round microfiber cleaning pads do miss cleaning the corners of the window. In addition, I did notice that the HOBOT-388 wasn’t perfect at cleaning the edges next to the window frames. That being said it did a very good job at cleaning the vast majority of each window.

The HOBOT-388 definitely does have a limit as to what it is capable of cleaning. One outside window had a mass of bird droppings adhered to it. The robot wasn’t capable of cleaning that off. However, after manually removing most of the bird droppings with a wet towel the HOBOT-388 did a good job cleaning up the rest and leaving the window streak free.

The HOBOT-388 doesn’t use a lot of fluid when it cleans a window so you can clean a number of windows before you have to refill the reservoir. I thought it might have a problem cleaning a window that the sun was shining on because the small amount of fluid sprayed on the window would evaporate too fast. But this wasn’t the case. It still did a very good job cleaning a sunny window. I do suspect (though I wasn’t able to test this) that the HOBOT-388 might have trouble if I lived near the ocean and my windows were covered with salt spray. That would require more liquid for cleaning than I observed the robot spraying.

There are a couple of things to be aware of about the HOBOT-388. First, the HOBOT-388 won’t work on windows with stickers and films applied to them. These make the surface of the window so slick that the robot will slip as it attempts to move across a window. It won’t fall off the window it just won’t be able to navigate properly to clean the window.

Second, HOBOT recommends that the HOBOT-388 only be used on sunny, low humidity days. Otherwise it can leave water streaks on the glass. Since, in many areas, high humidity is the norm, I checked with HOBOT on this issue. They explained that they recommend that the HOBOT-388 simply be used on sunny days and not directly before, or after, rain.

Third, HOBOT says that the HOBOT-388 can be used to clean surfaces besides glass. I tried to clean some Travertine tile in a bathroom. Either the smoothness of the tile, the grout lines, or the irregularities in the tile was too much for the robot to deal with. It didn’t fall but it slipped downward as it tried to navigate across the tiles. Be aware that there are going to be limitations if you want to use the HOBOT-388 on surfaces other than glass.

Finally, in between cleaning various windows, I put the robot down, upside down, so the wet pads wouldn’t be lying against a hardwood floor. What happened was that the water leaked out of the reservoir leaving a large puddle of water on the floor. I recommend simply having a towel handy to put the robot on.

Suggestions for Improving the HOBOT-388

I found the HOBOT-388 to be very capable at cleaning windows. However, there are some areas where I think the product could be improved.

1. When cleaning second-story windows outside a home, you may still need to use a ladder to place the robot on the window and retrieve it when the cleaning process is complete. Not all windows open and allow you to reach out and place the robot on the outside of the glass. A solution that would keep people from having to climb ladders to clean their windows would be to have a way to connect the robot to one of the extendable poles used by painters. A hook at the end of the pole could be used to attach and retrieve the robot from the window. In addition, if a suction cup was attached to the pole, it could be stuck to a corner of the window and the safety rope connected to the top of the pole. HOBOT has told me they are aware of this issue but still have some safety concerns using a pole to place the robot on a window. They are continuing to look for a solution that would provide the safety required for a commercial product.
2. I am not in favor of devices that have internal parts that, over time, will need to be replaced and are not serviceable by a homeowner. The internal, rechargeable, backup battery will last for several years but should be replaceable by a homeowner as any rechargeable battery will fail over time.
3. The power cord coming out of the plug-in power supply and the extension cable, when coupled together are approximately 16 feet long. This would be adequate to allow the HOBOT-388 to move about the vast majority of windows. In addition, the power cable includes a screw connection to minimize any chance of it becoming disconnected from the robot during operation. However, the connection between the extension cable and the power cable is only a simple press-on connection. I wrapped the connection with electrical tape to make sure they couldn’t become separated while the robot was operating. It would be nice if there was even a snap-on connector similar to one used to join extension cords, to eliminate any chance of these coming apart while a window was being cleaned.
4. The length of the power cable and the safety rope makes them challenging to store. Including some simple Velcro straps would be an inexpensive addition that would greatly help to keep the cables from becoming tangled.
5. I found that the HOBOT-388 wasn’t perfect at cleaning the edges of windows next to the frame. It would be nice if the robot finished its cleaning cycle by going back and making a second pass at the edges.
6. Besides windows, there are other glass surfaces in a home including glass topped tables and frameless shower enclosures. Unfortunately, the HOBOT-388 can’t clean these glass surfaces because they aren’t enclosed by a frame. It would be a nice improvement if the robot could detect edges on glass so it could clean these glass surfaces. HOBOT does include a laser that can detect the edge of a piece of glass on their HOBOT-298 window cleaning robot. I just wish it was also included on the HOBOT-388.
7. It was somewhat annoying that the app constantly sent notifications to only use water or HOBOT Cleaning Detergent. It would be much more user friendly to simply include a label by the reservoir on the robot with this message rather than sending a notification to the homeowner when they clean each, and every, window.
8. The HOBOT-388 isn’t overly loud, but it isn’t very quiet either. It seemed that the majority of the noise comes from the motor that creates the vacuum that holds the robot tightly against the glass. The noise seems to primarily emanate from the holes where the air from the vacuum motor is vented. I believe a minor change to the case design could help to reduce the noise level. This is, for example, done with mufflers for central vacuum systems to reduce the noise that comes from their vacuum exhaust port.

Conclusion

The above suggestions are very minor areas of improvement for an excellent product. It did a very good job of cleaning windows and it definitely made the job safer by not requiring me to get out a ladder to clean the outside of the windows on the second story of my home. The HOBOT-388 is not an inexpensive investment. But it can quickly pay for itself when compared to hiring a professional window cleaning service.