Cleaning & care

The "200 bar" claims of cordless washers

Let us say it straight away: the pressures claimed for battery pressure washers are theoretical peak figures, measured with the nozzle closed. A machine powered by a 21 V battery delivers, in real use, a pressure of the order of 20 to 45 bar, whatever the figure printed on the box. An entry-level mains washer stays above that.

That does not disqualify them, it shifts where their value lies: they wash a car with no tap and no socket, drawing water from a bucket, a river or a jerrycan. It is the only kind of machine that lets you wash while camping, in a car park or outside a garage with no water supply. Allow a flow of around 4 L/min and a real run time of some fifteen minutes per battery, which is one car per charge.

Vacuuming a cabin

The useful criterion is not the wattage on the box but the suction, and above all the attachments: it is the fine brush that reaches the seat runner and the crevice tool that goes between the cushions. A cordless car vacuum is for routine upkeep; for a cabin that has never been cleaned, you first have to lift the dirt with a detailing brush, otherwise the suction only takes the surface.

Polisher: what it corrects, and what it does not

An orbital polisher removes the swirl marks and wash marks, the ones that appear in bright sun as a cobweb pattern. It will not lift a scratch you can catch with a fingernail: that one goes through the clear coat and is a bodyshop job.

The orbital movement, unlike a rotary, does not burn the paint even if you dwell too long in one place: that is what makes it usable without experience. Two precautions are enough — work on a clean, dry car, and start at the lowest speed.

Phares jaunis

Yellowing is oxidation of the polycarbonate at the surface. An abrasive compound and a pad remove it, and the result is striking within half an hour. The point the kits rarely mention: without a protective lacquer applied afterwards, the oxidation returns within six to twelve months, sooner on a car parked outside.

The order that saves you time

Outside before inside, top before bottom, wheels last with a dedicated brush — a wheel brush used on the bodywork carries brake dust onto it, and that dust is abrasive. And wash in the shade: in the sun, the water dries before you can wipe it and leaves exactly the limescale marks you were trying to avoid.

The questions we get asked

Is a cordless pressure washer as good as a mains model?

Not on pressure: a 21 V battery device really delivers 20 to 45 bar, far from the peak figures claimed. Its value lies elsewhere: washing with no tap and no socket, drawing water from a bucket.

Can an orbital polisher damage the paint?

It is very hard to: the orbital movement does not concentrate the heat in one place, unlike a rotary. Work on a clean, dry car, and start at the lowest speed.

How long does a headlight restoration last?

Six to twelve months if no protective lacquer is applied after sanding, less on a car parked outside. Restoration removes the oxidation, it does not stop it coming back.