外媒：智能手机屏幕调暗真能省电吗？

Smartphone battery down to 10 percent? Time to turn down the brightness on the screen, right? It's a classic strategy to squeeze more juice from the battery. And it works. But that trick might be less effective than you think.

智能手机才10%的电量了?该把屏幕调暗了，对吧?这是争取更多电量典型的方法，而且切实可行。但那招没你想象得那样有效。

Because it turns out nearly half the battery drain on a phone happens when the screen's not even on. So says a study presented at a meeting of the Association for Computing Machinery.

因为事实上将近一半情况是屏幕暗着，但电池依然消耗着。美国计算机协会一次会议上发布的研究如是说。

Researchers eavesdropped on the activity of more than 1,500 Android phones—specifically, the Samsung Galaxy S3 and S4. They used an app they developed called eStar Energy Saver. The app logs the energy drain of the phone's apps and activities as they happen.

研究人员用他们研发的eStar能源节约助手监听了超过1500部安卓手机的活动——具体说来是三星Galaxy S3和S4。这个应用记录手机电池消耗情况及耗电时相应手机应用的状态。

They found that some 45 percent of the battery drain happened while the screen was off. A lot of that energy suck was apps updating in the background—downloading headlines and weather, while you're not actively using them.

研究发现有大约45%的电池消耗情况发生在屏幕暗的时候。许多电量不足是因为应用在后台更新——比如下载标题、更新天气，而事实上你根本没一直开着这些应用。

And different versions of the same app require different energy supplies. For instance, some versions of the Facebook app were twice as energy thirsty as other versions. So app version choice could slow your battery drain.

此外，同一个应用的不同版本对电量的要求也不尽相同。举例子说，有几个版本的脸书用电量是其他版本的两倍。所以说，选好版本也可以减缓电池消耗。

But one of the most hidden energy draws, zapping 12 percent of the battery, was just cellular paging: the pings from a cell tower every 1.28 seconds, that tell your phone if a call or message is on the way. Which is, ultimately, the price of being connected.

但最为隐蔽的电源消耗是蜂窝寻呼，可以用掉12%的电池，即手机信号塔每1.28秒就发一次的声脉冲，提示你来电或者有短信。这归根结底就是保持通信顺畅的代价。