Ever wonder why your cell phone charger feels warm when plugged into the wall, even if there’s no phone attached? This is a classic example of vampire power – the power your electrical devices use even when they are turned off or in standby mode.
Also known as phantom load, vampire power is no small blip on your energy bill. In fact, the Lawrence Berkeley National Laboratory estimates that vampire power accounts for 5 to 10 percent of all residential electricity use.
AT&T has recently released a new ZERO Charger that shuts itself off when a device is removed, even if the charger is still plugged into the wall. The charger uses a USB outlet, making it compatible with any phone, mp3 player, digital camera or gaming device (regardless of brand) that can be charged in a USB port.
Chargers are typically equipped with a sensor to determine when a device is attached, but in many cases that sensor has to be powered by electricity in order to work. That means if your cell phone charger is plugged in all day with no phone attached, you are using up to 10 watts of energy per hour to power nothing.
The ZERO Charger’s sensor is battery powered, meaning the energy supply is disconnected when the device is removed. However, tt will still draw energy if the device is plugged in and fully charged. In regards to cell phone charging, the charger has received Energy Star level V certification because it is 74 percent energy efficient.
AT&T says it will discontinue selling any other wall chargers except those for Nokia phones, which require a larger supply of power than the ZERO Charger can provide. The two companies are working together to address compatibility in the future.
While the ZERO Charger offers potential energy savings, it may not make a huge difference on your energy bill in the short term. Keeping a phone charger plugged in at all times will likely cost only $1-2 per month.