Chargers plugged in continuously: the true cost of their electricity consumption will surprise you!
At the beginning of the month, the newspaper Full Life published an alarmist article claiming that even when not connected to any device, smartphone chargers ” represent up to 11% of energy consumption in a home ” Skeptical of this impressive figure, we measured the consumption of 7 chargers ourselves.
Our test protocol
To do this, we used a variety of chargers: a 65W Asus laptop charger, and 6 smartphone chargers of 10W, 18W, 33W, 68W, 100W and 120W. We only used chargers supplied with the devices, from well-known brands (Huawei, Motorola, Honor, Xiaomi). All chargers were plugged into the same power strip, which was itself plugged into an energy cost meter.
To get the most realistic testing conditions possible, we also plugged USB cables into the chargers, some original, others from a box found in the darkness of a closet in the editorial office.
Once the test bench was set up, we started a 12-hour data recording (between 6:00 p.m. and 6:00 a.m.).
The results
After exporting and processing the data from the measuring device in a spreadsheet, the total consumption of the 7 chargers over 12 hours amounts to a “tremendous” value of 0.07 Wh, or 51.1 Wh per year. This is approximately the battery capacity of an entry-level laptop, such as the VivoBook Go 15 Asus. In terms of costs, considering an average kWh price of €0.2516 (EDF Base rate), this would amount to spending €0.013 per year, or 1.3 euro cents per year. This is indeed very little, and we must admit that we have difficulty imagining where the famous 11% of energy expenditure comes from.
A margin of error that is not so inconvenient
But we have to admit that we made a mistake in our measurements. When we were running the measurements, we consulted the energy meter's documentation (which we should have done beforehand, we grant you). We then realized that the manufacturer advertises a power measurement range of 0.3 W to 3,680 W, with a tolerance of plus or minus 0.3 W for powers below 3 W. However, during the entire test, the device never recorded a value higher than 0.25 W (apart from a very brief peak of 0.434 W at the beginning).
The only conclusion we can draw from this is that the power delivered was never greater than 0.6 W (minimum measurable value of 0.3 W plus the tolerance interval of 0.3 W). So we redid our calculations assuming that the chargers were consuming 0.6 W all the time.
But even under these “extreme” conditions, and even if the results are different, the conclusion remains very similar. With a total continuous power of 0.6 W, seven chargers plugged in “empty” consume 7.2 Wh over 12 hours, or 5266.9 Wh over a year. That is an annual cost of €1.33. The alleged financial abyss is therefore in reality only a small pothole.
Conclusion and risks
So, unless you only spend €12.09 on electricity per year, you can leave your chargers plugged in without them representing 11% of your EDF bill.
However, there are other reasons why you might want to unplug your charger when it's not in use. For example, some chargers no-name (which are not built by recognized brands) may not meet certain safety standards. We are thinking for example of chargers sold on sites like AliExpress or Wish, promising huge powers at unbeatable prices. These chargers tend to heat up, sometimes even when no device is plugged into them. This heating can, in the long term, damage components inside, or even cause fires in some extremely rare cases.
The chargers we used for this experiment were all from reputable brands, and we noticed almost no heating (about 1.5°C above room temperature) after being plugged in, empty, for more than 24 hours.
So, as with desktop computer power supplies, we can't recommend enough that you opt for quality chargers, or at least from well-known brands. If your device comes without a charger, you can get one from a well-known smartphone or laptop manufacturer, or from a brand such as Ugreen, Anker or Baseus.
