Really – how much (or little) power does the smartphone, laptop, or tablet really use? Do you need to unplug them when not actually using them to save cash on power? So we measured precisely the levels of power a number of the most common chargers utilize, and how expensive keeping them plugged in really can be.
You may have heard of a mysterious force known as vampire power. This is actually how much power a device uses while in standby; when you aren’t using it. So how much vampire power does a charger really suck, and is it really worth the effort of unplugging them whenever you aren’t using the devices?
How We Measured Useage
Trialing a wide number of chargers; from iPhone, iPad and MacBook, to many more, it was quite obvious to all that there was an issue with the very concept of the test. We were amazed to see – not one a single device tested used a detectable amount of vampire power while plugged into an electricity outlet.
Put simply, the Kill A Watt’s display read 0.0 watts, regardless of what was plugged into it.
That can’t be realistic!
It’s not totally correct to say that every charger was using 0.0 watts. Each charger is drawing some tiny percentage of a fraction of a watt. So at some time it should be detectable!
So we had a new idea — use a power strip with the meter and plug in a number of devices into the power strip.
Finally — after six separate chargers were plugged in, filling all the power strip’s electrical outlets — we detected a reading.
The total vampire power draw of this completely full power bar, an iPhone 6, an iPad Air, a Surface Pro 2, a MacBook Air, a Samsung Chromebook, and a Nexus 7 read 0.31 watts.
I See, so what does that mean financially?
So the number we have to work with is 0.3 watts.
We’ll assume these are all plugged constantly. So there are 8760 hours in a year. That equals 2.628 kilowatt hours (kWh).
According to the numbers at the US EIA, the average base cost of electricity in the USA is 12.98 cents per kWh. This means that those 2.628 kWh of electricity will cost a whopping 34.1 cents for a year.
The real cost is actually lower,as the devices are not plugged in constantly.
Vampire Power is fiction
This demonstrates that the amount of vampire power consumed by your chargers is irrelevant. It isn’t worth concerning yourself with. Just leave your chargers plugged in for ease; don’t bother to unplug them.