并非所有电缆似乎都是相等的，但我从来没有到底为什么这么多（廉价）电缆我尝试只收费 - 没有数据。任何人都知道为什么？某些引脚未连接？
我知道将较长的电缆或汽车到USB转换器无法传输足够的手机的电源来注册而不是充电，但我得到相反的。我不认为我是一个人（Nexus One Users的同样的问题这里）
Not all cables seem to be created equal but I've never got to the bottom of why so many (cheap) cables I try only charge - no data. Anyone know why? Certain pins not connecting?
I do know that longer cables or car to usb converters fail to transmit enough power for the phone to register and not charging but I'm getting the opposite. I don't think I am alone (same problem for Nexus One users here)
Broadly speaking, if you have a "USB" cable that only connects pins 1 & 4 then you will get power and no data (Best Buy was selling cables like that as Universal USB Charging Cables a while back, not sure if they still do). Likewise, if you have a cable with only 2 & 3, you will get data but no power. If you're curious, here's a Wikipedia page with the standard USB Pinout.
Note: Micro uses the same pinout as USB A.
As devnul3 says, a power-only cable is a USB cable where the data pins are not connected. The main reason they exist is because they can be made ever so slightly cheaper by virtue of only needing 2 connections instead of 4 (and also because you don't need to worry about preserving the quality of the very high frequency signals on the data lines).
This said, there are cases where a power-only cable is preferable to a "fully featured" USB cable: when you want to charge your device from some random USB connector somewhere. As is becoming more widely known, a USB connector can be used for many things besides the ones the user expects, so if you use a "normal" USB cable, you may end up unwittingly providing priviledged access to your device.
IOW when you're charging from a USB connector that you have no reason to trust, a power-only cable is not only ever-so-slightly cheaper, but it's also a bit safer.
Sorry to disagree with the other answers, but those assumptions are simply wrong: