How to tell a USB charge-only cable from a USB data cable

Ever tried to transfer files from a PC to your smartphone using a USB cable but the computer doesn’t recognize your device? — it only charges it. It happens, and we’ve all been there, I guess. But why does this happen though? Sometimes, the cable could be ‘fake’. It’s also possible that your cable is faulty or broken. But usually, there’s nothing wrong with your USB cable, it’s just not built for data transfer.

Types of USB cables

Because the majority of the USB cables being sold and shipped with smartphone support data transfer, you might have been wired to believe that all cables support data transfer. Well, they don’t.

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Generally, there are two types of cables;

  1. Charging cables: can only charge your smartphone and other devices but cannot transfer data. These are commonly called “Charge-only” cables.
  2. Data cables: does both; charges your devices and transfer data.

How (and why) are these cables different?

What differentiates a charge-only USB cable from a data cable is the how they are produced. More precisely, their wiring system — the number of wires within the cable. Underneath the fancy body of your USB cables are wires, right? The number of wires a cable has will determine if charges your phone, transfers data, or does both.

USB cable wiring system

Data cables typically contain four wires (positive, negative, data transfer & data receive). The positive (+) and negative (-) wires carry electric power to the device while the other two data transfer (D+) and data receive (D-) wires are responsible for data exchange. Charge-only cables, on the other hand, only have the positive and negative power wires but lack the data exchange wires.

All USB cables have the positive and negative wires (because they are the most important) but not all USB cables have the data exchange wires — this is why some cables only charges your smartphone.

A USB Data cable (with 4 wires)

How to tell the difference

Because the USB Implementers Forum doesn’t have any rule enforcing USB manufacturers to label or differentiate charge-only cables from data-transfer cables, it is almost impossible to tell them apart. However, there are still some proven ways to find out if a USB cable is charge-only or supports data transfer.

1. Physical examination

Due to the number of wires in them, USB data cables are usually thicker than USB charging cables. Data cables have four wires and as such, have thicker outer insulation/lining than their charge-only counterparts with two (2) less wires.

USB data cable vs USB charging cable
A USB Charge-only cable (with 2 connected wires)

2. Contact customer support

If you are purchasing a USB cable online, and the product page doesn’t explicitly state that the cable supports data exchange, the best bet is to contact the website’s customer support for confirmation. If you’re purchasing the cable in an offline store, be sure to meet the store attendant to confirm that the cable you’re buying is indeed a data cable.

3. Preliminary test

Another way to tell a USB charging cable from a data transfer is to actually test the cable(s). Since the USB Implementers Forum does not have a standard, symbol, label, or icon to distinguish these cables, you actually have to use them to find out.

If you are having problems accessing your device on your computer, or your smartphone is charging only, then your cable most definitely isn’t a data-transfer USB cable.