Charging a laptop differently, what's the price difference?
We took four different laptops of different ages and measured the kilowatt hours of energy used during a 24-hour period for three popular charging scenarios:
Plugged in We left each laptop plugged in for a full 24-hour period
Charging when you need it (20% to 100%) Over an eight-hour working day we put each laptop onto charge every time it got down to 20% battery remaining. We left it on charge and then unplugged the charger every time each laptop reached 100% fully charged. After the eight hours we unplugged the charger for a further 16 hours, then took our measurements.
Charging when you need it (30% to 80%) Over an eight-hour working day we put each laptop onto charge every time it got down to 30% battery remaining. We left it on charge and then unplugged the charger every time each laptop reached 80% fully charged. After the eight hours we unplugged the charger for a further 16 hours, then took our measurements.
Here's what we found:
Method of charging | Average yearly cost | Yearly savings by switching from 'Plugged in' to this method |
---|
Plugged in | £7.74 | n/a |
Charging when you need it (20% to 100%) | £7.60 | £0.14 |
Charging when you need it (30% to 80%) | £6.83 | £0.91 |
Table notes: average laptop age 2.5 years, average laptop battery capacity 48.1Wh, average yearly cost - assumed a laptop is used five days a week, representing a typical working week, electricity unit price £0.34/kWh | | |
It turns out that charging a laptop isn't one of the big energy guzzlers. Although leaving your laptop plugged in all day uses a little more energy than just charging when you need it, the yearly savings aren't huge.
The most our snapshot test showed was an average saving of 91p a year if you charge your laptop when you need it.
But if you have multiple laptops in your home, or feel charging your laptop in the cheapest way possible is a habit you can change, there are savings to be made.