I’ve had my Karcher OC-3 for a few months now. It’s a fairly compact little unit housing a water reservoir with a capacity of 4 litres, a battery pack with a run time of about 15 minutes, and a jet washing nozzle and hose that’s permanently connected into the control unit but all stores inside.

It’s a tidy little solution to the never ending problem of putting a muddy bike into a car. You don’t want to do it, you know you shouldn’t do it, and you definitely will regret it later.
The unit comes with a charger brick. Non standard of course, but it is 12V and a car charger is available. Again non standard. The connector is a two pin job. Why they couldn’t have standardised on one of the existing ones, heaven only knows! I presume so they can charge a silly amount for car chargers (£24 in case you’re wondering).
The unit itself is just a washer. You can’t put soap in it. Well, they tell you not to. The universe won’t end if you do but you’ll probably clog it up – so be prepared to carry a spray bottle of Muc-off or similar. The supplied nozzle gives a low pressure flat spray which does a fine job of even fairly hefty mud.

The spray unit itself is light enough to hold if you want, but works mighty fine on the floor too. A couple of minutes rinsing, followed by an application of Muc-off and a second couple of minutes rinsing is enough to clean pretty much any state of bike.
So what’s the good?
Well having a portable jet wash is stunningly good. Having a clean bike when you get home is even better.
The bad?
Over £110 for a rather low powered jet wash is a lot to swallow; and then the insult that the 12V charger costs almost a fifth the price of the unit.
The inability to use soap is another bad point – more stuff to carry – although the battery life didn’t cause problems. 15 minutes gets a wash done on three bikes.
The biggest problem, however, is the 4 litre capacity. You’ll be forever filling it, although you can get a part to drop into a bucket or even a stream if you want a more consistent flow of water. You’ll need a big container of water to keep with you. Even more load to carry!
The verdict 🟡🟡🟡🟡🟡🟡🔵🔵🔵🔵 6/10. A nice idea, but expensive and with a few limitations. If you’re rolling in money, it’s a good idea, but if you’re not use the local stream!