Worried families looking at ways to cut down energy use are looking at every appliance and gadget which is plugged in to save money.
But some of these things cost just pennies to use, and stressing over minimising their power usage is largely a waste of time. One such gadget is your mobile phone, which is often targeted by households under the impression that just plugging it in to charge when necessary rather than overnight is one way you can save money.
Technically, they are correct - but the savings are so tiny, it's not worth changing your behaviour to make them. Consumer group Which? has done the sums by comparing alternatives to charging when you are sleeping, and have found that amount you will save by changing your habits is a maximum of 40p - a year.
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The consumer group did three tests on four different mobile phones of different ages and brand and measured the kilowatt hours of energy used for three popular charging scenarios:
Charging overnight Each phone was put on to charge when it got down to 20% battery remaining and left it on charge for seven hours every night
Charging when you need it (20 to 100%) Each phone was put on to charge when it got down to 20% battery remaining. It was left on charge and then unplugged when the phone reached 100%, charging once a day
Charging when you need it (30 to 80%) Each phone was put on to charge when it got down to 30% battery remaining. It was left it on charge and then unplugged it when the phone reached 80%. Doing this means the phone needs to be charged more frequently, so the figures assumed an average of 1.5 charges per day.
Which? found that charging overnight cost around 0.5p per night or a total of £1.74 per year, charging at 20% but unplugging as soon as your phone was fully charged cost around 0.4p or £1.37 a year and charging your phone at 30% until it reached 80p cost around 0.2p or £1.34 a year.
In other words, changing your charging habits would save you 37p a year to charge and unplug when needed or 40p a year to part charge when needed.
"Charging a mobile phone costs less than a penny per charge. Leaving it plugged in overnight uses a little more energy but the most our quick investigation showed you could save was an average of 40p a year if you charge your phone when you need it," said Which? "If you have multiple phones in your home, or feel charging your phone using the least energy possible is something you want to do, then it will keep a few more pennies in the bank, but it's not going to make a big difference to your energy bills."
Emily Seymour, Which? sustainability editor, reckons that householders should concentrate on bigger hits if they need to make a dint in their energy bills. "For most households the biggest energy guzzlers through the winter are central heating and appliances such as tumble dryers," she said.
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