Question: Do Phone Chargers Waste Power? Good Question: Straightening Out Cell-Phone Chargers and Their Power Consumption
By PETER SVENSSON The Associated Press
- Q: Does my cell-phone charger consume electricity if I leave it plugged in to the wall when it's not charging the phone?
A: It probably doesn't consume a significant amount, unless you have a really old cell phone. You may have heard that "all power adapters use electricity if you keep them plugged in," but it's not quite true anymore.
I used an inexpensive P3 Kill A Watt electricity meter to test six cell-phone chargers from five manufacturers, and found that none of them used a measurable amount of power when not charging a phone. None of them were older than a few years. One of them did use power when connected to a fully charged phone, but it was less than half a watt.
If you have an older charger, you can test it by plugging it in, and then feeling if it gets warm to the touch. That may indicate that it's a so-called "linear" power supply. These are generally larger, bulkier, and less efficient at turning alternating current from the power grid into direct current usable by an appliance.
Modern chargers are called "switched-mode" or "switching" power supplies, and use chips to convert AC to DC. Some of the larger versions of these adapters, like the ones built into computers, do use electricity when the appliance is off. The Kill A Watt widely available online told me my desktop PC uses 2 watts when it's off, as does the hefty power brick of the Xbox 360 game console. The adapter for my wireless router uses about 1 watt. A few other adapters used about a third of a watt.
The wattage numbers aren't large, but they add up, especially when you consider appliances that don't really turn off, like DVD players that remain in "standby" mode. My laser printer, for instance, doesn't have an "off" button, and sips 6 watts, according to the Kill A Watt. That costs me $10 a year.
To cut off these trickles of electricity, you could connect your appliances to a power strip and turn it off when they're not needed. You can also look for appliances certified under the U.S. Environmental Protection Agency's Energy Star program, which sets standards for power used in standby mode.
The EPA has also taken an interest in cell-phone chargers, but their focus hasn't been on power consumption when not in use. The problem is rather that the adapters are often inefficient when they are charging. With some chargers, less than half the energy ends up in the cell phone's battery. The rest turns into heat.
The EPA has introduced Energy Star Criteria for power adapters, and manufacturers appear to be responding. Last month, Motorola Inc. said it would redesign all its cell-phone and accessory chargers to comply with the standard. Samsung Electronics Co. began introducing some Energy Star chargers last year.
According to the EPA, if every phone sold in the U.S. this year used an Energy Star-qualified charger, the energy saved could light 760,000 homes for a year, or prevent greenhouse-gas emissions equivalent to those of more than 200,000 cars annually.
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