Recently, AT&T announced an eco-friendly cell phone charger called the AT&T Zero Charger.
The allure of this device is it automatically shuts down when not in use, offering what AT&T claims is "zero vampire draw" from the wall outlet. Vampire draw is a term for the power that devices draw out of outlets they are plugged into while they are turned off. AT&T's charger will be USB-compatible, making it practical for many of the phones on the market today.
Sure, a zero-draw charger sounds helpful. With that said, we here at CNET were a tad curious as to how much power current chargers draw when left plugged in. Is it significant, or is AT&T selling us something we don't need?
We conducted our own anecdotal test here in the New York Labs with some of the more common cell phone chargers from the major manufactures. We power-tested the Apple iPhone, the Motorola Droid, the Palm Pre, and the Nokia Nuron chargers at least three times per charger.
We calculated the draw over a 16-hour period when plugged in with no phone attached, leaving out the 8 hours of nighttime during which an average phone will typically be charging.
|Phone Charger||16-hour charger draw (watts)||Cost per year|
|Palm Pre (with TouchStone)||0.3333||$0.22|
|Palm Pre (without TouchStone)||0.0998||$0.07|
As you can see, we already have a zero-draw charger on the market: the Nokia Nuron's charger. Though the Nuron's charger isn't USB compatible, it's the most eco-friendly of the five phone chargers we tested.
But, even in the case of the non-zero-draw chargers we tested, they all drew an extremely low amount of power and cost the user very little per year, ranging from 6 to 22 cents based on our calculations. If we assume $29 (the cost of your average charger, assuming AT&T's Zero Charger would cost the same) and divide it by 12 cents (the average of all four chargers' annual costs), it would take 241 years for it to pay for itself.
On the other hand, though the vampire draw on most of these chargers is negligible for the average individual, collectively across the world this can add up to some significant power usage. Zero draw is a great global goal in the long run.