The State of USB Charging

The humble Universal Serial Bus, more commonly known as USB has evolved to be much more than just a way to connect a mouse or keyboard to your computer. With the proliferation of power hungry portable devices that charge over USB, we’ve all come to expect USB to operate as a Universal Source of Battery charging, but unfortunately it’s just not that easy.

The original USB 2.0 specification limited the power that could be drawn from any USB port to 500mA. This is plenty to charge smaller batteries reasonably quickly, but for larger batteries a higher power solution is needed. This has driven device makers to come up with novel ways to draw more than the allowed 500mA from USB 2.0 ports and in general has been accomplished by the USB port signaling to the devices that it’s ok for the device to draw current at a higher rate.

Unfortunately there hasn’t been a widely adopted standard, so not all ports and devices speak the same language when it comes to charging. And, to make the situation even more frustrating for end users, there hasn’t been much public discussion or documentation about what has been done.

iPads for example, are one device that can charge at a very quick rate, up to 2.1Amps when connected to an Apple computer or Apple charger but they will potentially not charge at all when connected to a regular USB port. There’s also the BC 1.1 charging standard that some devices like the Kindle Fire or the Nexus 7 support, but that support is usually undocumented. We find out about charging behavior through trial and error.

So, try we did! We’ve been working hard to unravel the mysteries of what will charge where by testing every device we have on all of our hubs and chargers, and publishing this data on the product pages for each of our devices with USB ports.

We’re also collecting reports from end users though a quick form that let’s you add to the knowledge base of charging behavior.

Here’s what’s been added so far:
plugable.com/support/charging

To add your device visit:
plugable.com/support/charging-report

Check the FAQ on each of these pages for the details of our in-house test results.

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