Scam or handy gadget? Test heated car mats

There are many well-known ways to deal with the swamp underfoot – from old-fashioned crumpled newspapers and snowballs to modern moisture-absorbing rugs “a la diapers”. They generally all work. But we haven’t thought about the idea of ​​pulling electricity to our side yet. Buy a special heated mat, put it on the floor under the usual one, plug it into a 12V outlet – and that’s it?

It was possible to quickly purchase several similar products worth no more than 2,500 rubles. But then the question arose: what, in fact, is there to check? How should they work? Where do ice, snow and water disappear under your feet after plugging in?

• estimated price 1500 ₽
• Dimensions 400×400mm
• Wire length 1.3 meters
• Consume electricity 4.5A

At room temperature, it warms up to 58 ° C. The highest power, but such a product does not radically eliminate the water under your feet. The plug has a built-in blue LED, dazzling in the dark. We can’t recommend it.

• estimated price 1700 ₽
• Dimensions 410×400mm
• Wire length 0.9 meters
• Consume electricity 3.5A

At room temperature, it warms up to 50 ° C. The average power product in our example, devoid of any benefits. We can’t recommend it.

• estimated price 2400 ₽
• Dimensions 350×350mm
• Wire length 1.0 meters
• Consume electricity 2.9 A

At room temperature, it warms up to 42 ° C. The product itself looks better than its counterparts and is even equipped with Velcro for fixing to the floor. This is where the advantages end: the power is the lowest, it makes no sense. We can’t recommend it.

Question theory

Evaporating, you say? The theory is in textbooks: the evaporation rate of water mainly depends on the temperature, the area of ​​the evaporation mirror, the intensity of air currents, pressure and the like. It is clear that the carpets we bought can only change the temperature of the liquid: the rest is a priori beyond their control. But how much will this increase the rate of evaporation?

You can perform the simplest experiment yourself: you only need two identical saucers with water. We put one in the refrigerator, let the other come to room temperature – and compare the time the saucers are empty. We did something similar: at +4 °C the dish dried out after a week, at +21 °C after three days.

For the sake of interest, let’s calculate how long it takes for such a heater to raise the water temperature from at least the declared +4 ° C to +21 ° C? This is again from a physics course at school: you have to multiply the heat capacity of water by its mass and by the temperature difference, and then divide the resulting product by the heating capacity. Well, let’s guess:

T = CM (t₂ – T₁)/P

Where:

• T – desired time
• OF — heat capacity of water (1 kcal/kg gr.)
• m – mass of water
• T₁ And T₂ — Initial and final water temperatures
• R — heating power

We substitute a mass equal to 1 kg (an ordinary pool mat easily absorbs a liter of water) and a power of 0.03 kW. At the same time, we translate joules into calories with a coefficient of 4.19, and seconds into minutes – we get about forty minutes. During this time, the cold puddle under your feet will warm up a little – that’s all. It is already clear how quickly the container of water, in which the legs of the driver and passengers remain, will dry out completely, and even if there is ice after a night’s parking in the cold, it is already clear: in reality – never !

However, we set up another simple experiment: we take a real rug and put it in a freezer, frozen to minus 25 ° C: let it heat the water there. Before starting the experiment, we turned off the freezer: let the mat try to thaw a modest cuvette of ice, at least under such light conditions. After a few hours the spot was stopped: and so everything is clear. The surface of the carpet barely warmed up to +12 ° C.

And other arguments against

Electric 12-volt auxiliary heaters in the cab have always been useless toys. Even with a power of up to 300 W, they did not heat up, although they ate quite a lot of power.

Purchased carpets are their energy efficient relatives: they are useless. The regular interior heater copes with the task much better: it heats the water under your feet faster. But even he is unable to vaporize it effectively. By the way, evaporated water, including, settles on the glass, deteriorating vision.

That’s not all. Not all cars have a 12V socket that is de-energized when the engine is switched off – Skoda can serve as an example. As we explained in NAMI, no one fulfilled the mandatory requirements for the functional scheme of power supply / disconnecting sockets / cigarette lighter 12/24 V. Hence the conclusion: most owners of such cars will almost certainly forget to turn on the heated mats in time from the network, which will lead to a discharge of the battery, or worse, an uncontrolled fire.

And during the “debriefing” no one takes the side of the consumer:

• the manufacturer of the car – because he did not allow you to hold what you held;
• traffic police – because by using an additional heater, with it you have, as it were, made a change in the design of the car, and this is prohibited;
• gadget seller – because he doesn’t know if you used his device correctly. And in general, you don’t go to China to complain;
• insurance company – see point 1.

Our verdict is simple: we cannot recommend such products – there are more convenient ways to spend 2500 rubles.

Our advice

If your car does have puddles, the best way to remove them is to pour water from the trays and then use moisture-absorbing products, such as car diapers. To prevent, especially on long journeys, it is worth directing a strong stream of the hottest air from the stove to the legs. It will be hot – ventilate the interior by lowering the windows. And when landing, shake the snow off your feet: less moisture – fewer problems.

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