There are many people who do this: before going to sleep, they leave their cell phone to charge, so that the next morning it has a full battery and can withstand another day of use. There are those who wonder: could it be that, by opting for this solution, our chargers spend the whole night consuming energy, even after the mobile phones are already fully charged?
Experts tell PÚBLICO that consumption is very low, not having a relevant weight in what is the energy bill. That said, they also point out that, if we add this to other similarly derisory consumption, we are suddenly left with a small set of expenses that it will be worth thinking about eliminating.
Pedro Nunes, from the Zero environmental association, clarifies that “equipment with a battery has a residual discharge, which happens all the time”. The specialist says this to explain that the chargers of our mobile phones, even when they have a full battery, are “always in alert mode”. The batteries in most modern devices stop charging when they are full, but the charger will power the phone again when the charge drops to 99%.
This means that even after charging itself, there is still energy consumption. Not that this is huge, emphasizes Pedro Nunes. While the charge is still reaching 100%, the charger’s consumption is fixed at five to ten watts of energy, he estimates. After the mobile phone is already fully charged, the charger begins to “work at half gas”, dropping consumption to “two to three watts” (by the way: if a charger is connected to the socket without being connected to a device, the value is around 0.5 watts, according to the Zero specialist).
The expense is quite small, he admits. “If I have equipment consuming 1000 watts (an oil heater, for example), it will, at the end of an hour, consume one kilowatt-hour. The cost of this is about 20 cents (of course this varies depending on the energy supplier). Comparatively, two to three watts is very low, even negligible.”
But having our devices connected to their chargers longer than necessary can lead to other problems. “As the charger will always ensure that the equipment is at 100%, there will be a constant charge-discharge which, over time, can reduce the useful life of the battery”, he warns.
Miguel Sequeira, member of the Center for Research in Environment and Sustainability (Cense), recommends that owners of mobile phones with this functionality activate the “smart charging” option, which in theory allows to extend the useful life of the batteries.
There are also mobile phones that give the user the option of not charging them to 100%. “Batteries don’t like extremes”, explains Pedro Nunes, saying that, for chemical reasons, the best thing is for the charge to always be between 20 and 80-85%.
Miguel Sequeira, who is also a collaborator of the Study Group for Territorial and Environmental Planning (GEOTA), agrees with Pedro Nunes when he points out that leaving the cell phone charging all night costs merely residual energy. However, he argues that if we add this consumption to that of other devices that we often leave in stand-by (or else that are constantly connected to the plug), we start to have a series of small expenses that maybe we should think about reducing.
“A box on television many times in stand-byO router of the Internet always connected to the socket, certain household appliances (such as washing machines, which are usually always connected to the mains)… If we start to add all this up, small consumptions can become a little more relevant”, he says. .
The researcher alludes to Green Renewal Menu, a platform co-created by Cense that aims to help people make their homes more sustainable. O site includes several tips on energy use. Two of them are “turning off the equipment” (that is, removing them from the plug, instead of leaving them on). stand-by) and eliminate so-called “ghost” consumption, which occurs when appliances, despite not being in operation, remain connected to the current.
“This small measure, combined with the elimination of stand-byyou can reduce your energy bill by up to 11%”, promises the Green Renewal Menu, which even gives some examples of “appliances with consumption in stand-by” (“box, routercomputer, printer, coffee machine and audio equipment, among others”).
In short: leaving our cell phones charging all night is not something that translates into an abysmal bill. But maybe it might be worth rethinking the way we relate to our shots.