Product test

Kärcher SE 3-18: this battery-powered wet vacuum cleaner has won me over

21.8.2023

Translation: Katherine Martin

When a typical vacuum cleaner just won’t cut it, getting yourself a wet vacuum cleaner is the next logical step. Being battery-powered, the Kärcher SE 3-18 Compact is super wieldy – and rigorous to boot.

As summertime draws to a close, you begin to see the traces it leaves behind. The garden lounge cushions have certainly seen brighter days. And the kids have spent many an hour strewing biscuit crumbs over the back car seats. Or was it a chocolate bar?

Though you can get superficial stains out with a dry vacuum cleaner, a wet vacuum catches that deep-seated dirt. Living up to their name, wet vacuums work by spraying the material with water, then sucking the droplets right back up.

The Kärcher SE 3-18 Compact is one of these devices. When I clap eyes on my test vacuum for the first time, I instantly like it. After all, my car is just the place where cables and hoses prove to be a nuisance. Kärcher has at least got rid of the cable – the device runs on battery power. It also has an integrated water tank, so it doesn’t need to be hooked up to the water supply.

Wet floor cleaner

−7%

CHF109.– was CHF117.–

Kärcher SE 3-18 Compact

Coming in at well under 200 euros or Swiss francs, the vacuum boasts a cutthroat price tag. The thing is, you won’t get the whole package for this. Before you can kick off your cleaning spree, you’ll also need a battery and a charger. There’s no connector for a power outlet. Alternatively, you can go ahead and buy a set. Depending on the battery size, this adds at least another 100 euros or Swiss francs to the price. At least you’ll have the option of using the battery for other Kärcher devices. That is, if you have any.

Tool batteries + Chargers

CHF71.90

Kärcher Battery Power 18/50

18 V

Kärcher Quick charger 2.445-032.0 (18 V)

Tool batteries + Chargers

CHF30.70

Kärcher Quick charger 2.445-032.0

18 V

Tool batteries + Chargers

CHF109.–

Kärcher starter kit

18 V

Tool batteries + Chargers

CHF109.–

Kärcher starter kit

18 V

The 5-Ah battery pack I got for this review holds out for 25 minutes. Compared to stick vacuum cleaners (which themselves often have low-capacity batteries) this isn’t much. Mind you, pumping out and sucking up liquids does eat up that extra bit of power.

Box contents and product specs

Having taken everything out of the box, things seem uncomplicated. Quite the opposite of the time I tried out the Kärcher’s SE 4001 carpet cleaner. The SE 3-18 (I won’t bother mentioning the «Compact» from here on out) is a spray extraction cleaner too. However, the small tube that adds detergent to the water is integrated into the suction hose. Since it doesn’t need to be attached externally, putting the device together is child’s play.

A few things immediately strike me as positive:

At 1.9 metres, the suction hose is surprisingly long.
The fresh water tank holds a cool 1.6 litres.
The dirty water tank accommodates 1.6 litres too – which actually makes sense.

Here, you can see the tanks next to the SE 3-18. Just pop them into the vacuum, and you’re off.
Source: Martin Jungfer

The SE 3-18 weighs five kilogrammes without the battery, while adding the more powerful battery piles on another 800 grammes. Then there’s the weight of the fresh water. Tipping the scales at just under seven kilogrammes, the vacuum is easy to carry. Even so, it’s handy Kärcher has kitted out the device with a carry handle.

The carry handle makes it easy to transport the SE 3-18 to where it’s needed.
Source: Martin Jungfer

How good is the suction on the SE 3-18?

Now, although we sell the SE 3-18 in our «vacuum cleaners» category, it can’t do dry vacuuming. It’s specially for wet-cleaning upholstery and carpets. This means you’ll want to remove any coarse dirt from the surfaces you want to clean with the SE 3-18 using a regular dry vacuum cleaner first.

Another bit of prep you’ll have to do is filling up the fresh water tank. To do this, you simply pour the included detergent into the tank and fill it up with regular water. Before you’ve used up all the detergent, you should order a refill. The RM 519 is the one you’ll need for the SE 3-18. Kärcher strongly advises using its own-brand detergents. In theory, you could fill it with other cleaners as well. Get the dosage wrong, however, and you might clog the nozzles. Not only that, but if you haven’t followed the instructions in the user manual, you’ll obviously run into problems if you ever need to raise a warranty case.

The 100 millilitres of detergent included with the vacuum go into the fresh water tank. Top it up with tap water, and you’re ready to rock.
Source: Martin Jungfer

Cleaning products

Quantity discount

CHF8.70 per piece for 4 units CHF8.70/1l

Kärcher Carpet cleaner RM 519

For my first test, I grabbed our door mat. Though it gets regularly vacuumed and sometimes washed, it’s been several weeks since its last spa treatment. Before I get started, I give the mat a once-over with a dry vacuum. Then, I forge on with the SE 3-18. I’ve mounted the upholstery nozzle, which measures in at roughly seven centimetres wide. This is certainly too small for a larger rug – even more so for a carpeted room. For a trial run on the door mat, however, it’ll do just fine. If you’re going to be cleaning larger carpeted areas, I’d recommend the Kärcher SE 4001.

Back to the door mat. I turn on the vacuum and set the carpet nozzle at a 45-degree angle. I pull the nozzle over the carpet in straight lines, holding down the spray button on the handle with my index finger. Pressing the button dispenses the cleaning fluid, which is then instantly vacuumed back up. With this in mind, it makes sense to work by pulling the vacuum towards me. The Plexiglas means I’m able to see how the device works. In a nutshell: clean water goes on the carpet, then dirty water comes off it and back into the SE 3-18’s dirty water tank.

In this close-up shot, you can see the dirty water being sucked back in.
Source: Martin Jungfer

This works so well that I grab the floor mats from my car next. This time around, the superiority of the wet vacuum cleaner over a regular dry variety is even more apparent. Once I finish vacuuming and leave the floor mats out to dry in the sun, they’re hardly recognisable. They’re almost as clean as the ones you get in a new car. I’m impressed. I’ve never been able to get results like this with the vacuum cleaner at the car wash around the corner.

Floor mat trio: almost as good as new after being cleaned with the upholstery nozzle.
Source: Martin Jungfer

The battery display tells me it’s got 15 minutes of runtime left. I go on to clean the car boot. In places where dirt can get really embedded in the felt, the SE 3-18 reaches its limit. Even the detergent in the tank and my repeated attempts at vacuuming don’t get all the stains out.

It does a better job of the upholstery on the car seats. At least in places where the entire upholstery nozzle can be placed flat on the fabric. As I’m tackling the side bolsters on the front seat, water splashes onto the centre console. Time to switch to a narrower nozzle. This allows me to get right into to the car seats’ nooks and crannies. Mind you, it does make vacuuming much more laborious.

After about 20 minutes, the Kärcher’s fresh water tank is already empty. Much sooner than I’d expected. Having used up the first 100 millilitres of detergent concentrate, I mix up some more to clean the rest of the car upholstery too.

How do you clean the SE 3-18?

Once I’m done, the battery still has enough capacity for the self-cleaning process. The Kärcher’s user manual recommends doing this after each use. Here’s what you need to do:

Empty the dirty water tank and clean it out.
Empty the fresh water tank if there’s still cleaning liquid inside.
Fill the fresh water tank with tap water.
Attach the crevice nozzle to the hose.
Insert the nozzle right into the opening of the fresh water tank.
Switch on the device.

The tank’s 1.6 litres of water take under a minute to circulate through the SE 3-18. This is usually enough for you to stop and leave the components to dry. Once that’s done and dusted, you can put the device away until it’s next needed. If you place the empty battery on the Kärcher quick charger, it’ll be full and ready for use again after about an hour and a half.

Once clean, the SE 3-18 parts should dry off nicely.

The dirty water tank shows how much dirt a wet vacuum can get out of textiles that a dry vacuum can’t.
Source: Martin Jungfer

It’s worth having a look at the plastic sieves occasionally. There’s one at the bottom of the fresh water tank and another at the top of the dirty water tank. If dirt has built up there, you can get remove it with a cloth or a small brush.

How does the SE 3-18 handle?

Using the SE 3-18 is so easy that I almost don’t need the manual. The only bit I need to reread to be on the safe side is the «system cleaning» section, with the part about the rinse cycle. The battery solution is particularly nifty, in my opinion. Instead of having to push it into some fiddly opening, I just hook it up to the outside of the device. Kärcher has also come up with a clever solution for the display. When the device is being used, the display changes to show you the remaining runtime in minutes. The rest of the time, it displays the charge level as a percentage.

The battery display shows either the remaining run time in minutes or the battery level in per cent.
Source: Martin Jungfer

The upholstery- and crevice nozzles are okay from an ergonomic standpoint – no better, no worse. If your hand is wet, the nozzle stops being easy to hold. Holding down the spray button also gets a bit uncomfortable in the long run. The rubber strip embedded in the hard plastic is too narrow to give me enough grip.

I’ve got to be careful when using the upholstery nozzle on curved surfaces. Not taking enough care here, I splashed cleaning solution on the centre console.
Source: Martin Jungfer

Verdict

While the SE 3-18 seems inexpensive at first glance, the battery needed in addition makes this supposed bargain much pricier. Even so, you do get a good device for your money overall. The wet suction power is perfect for cleaning car floor mats or even upholstery. Cars in general are a kind of natural habitat for the SE 3-18. It’s where the device’s strengths truly come into play. The long, flexible hose allows you to reach anywhere easily. Since the battery pack means you don’t have a power cable in your way, cleaning your car is much easier. If your garden lounge cushions can’t be removed and washed separately, they’ll also be a boon to your SE 3-18.

With its 5-Ah capacity, the large battery provides a good 25 minutes of power. That should be enough for a car. If it takes you longer, you might love your car a little too much. The smaller battery, with a capacity of 2.5 Ah, lasts half as long.

Investing in the battery is worth it if you can use it with other Kärcher devices. Unfortunately, Kärcher is the only player in the field of rechargeable batteries, so their battery packs aren’t compatible with devices made by other manufacturers. The Power For All Alliance, including Bosch, Gardena, Husqvarna and Rapid, is better positioned in this regard.

Do you have any questions about my Kärcher SE 3-18 review? Used a vacuum cleaner like this before and fancy sharing your experience? Feel free to hit the comment section!

Header image: Martin Jungfer

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Martin Jungfer

Head of Content

Martin.Jungfer@digitecgalaxus.ch

Journalist since 1997. Stopovers in Franconia (or the Franken region), Lake Constance, Obwalden, Nidwalden and Zurich. Father since 2014. Expert in editorial organisation and motivation. Focus on sustainability, home office tools, beautiful things for the home, creative toys and sports equipment.

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