Google engineer challenges USB-C cables for sale at Amazon

By Joel Hruska

There’s a basic assumption that underlies cable purchases, even among techies. It’s the idea that most cables are created equal, and that you can grab any cable from a well-regarded supplier or manufacturer and come out on top. Recent reviews at Amazon from Google engineer Benson Leung challenge this assertion as it applies to USB Type-C cables, and the results aren’t pretty.

Leung is a software engineer on the Chrome OS team, as well as an engineer on the Chromebook Pixel and Pixel C teams. He’s reviewed multiple USB Type-C convertor cables manufactured by companies like Frieq, CableCreation, Belkin, Monba, Kupx, iOrange, Juiced Systems, Orzly, and Techmatte, evaluating each for whether or not it meets the USB group’s specifications. The results are mixed (to put it mildly).

A USB Type-C port next to USB 3.0

The Frieq, Belkin, and iOrange cables all meet the relevant USB-IF specifications for their respective features. The rest have one of two serious problems. CableCreation’s adapters advertise themselves as being 3A capable, but don’t contain internal circuitry capable of supporting that power level. Instead of using a resistor of value 56kΩ, CableCreation used a 10kΩ pull-up. A device capable of drawing 3A might attempt to do so, with rather ugly results. The Kupx and Techmatte adapters have the exact same problem, while Monba’s adapter doesn’t identify itself properly at all.

Several manufacturers have defended their product specifications, but with no great success. The problem, as Leung explains, is as follows:

By setting the 3A resistor setting, you may cause damage to wall chargers, hubs, or PC USB ports that are NOT rated at 3A because the device will attempt to pull 3A and while the Type-A host on the other side may be ANYTHING made with a USB-A port since 1997.

The specification dictates that you MUST use a 56K pullup to identify as ‘Default USB Power’ source if you use a legacy cable in order to protect weaker chargers, hubs, and PCs that have been made in the last 18 years…

Using your bad USB cable, I have personally seen a high quality Anker charger in a brown out cycle continuously until I unplugged your cable and my Type C device charging from it.

By selling a cable that has a Type-A plug on one side but a resistor that should only be used when there is pure Type-C charging path (ie, C-C cable to a C port), you risk damaging people’s older hardware with your out-of-spec cable.

Cable quality: Easy to lie about, difficult to verify

It’s great to see someone tackling this issue, even if the results are only given in relation to Chromebook Pixel hardware. Some cables are easy to test for functionality — either they work or they don’t — but many aren’t that accommodating. All of the USB Type-C cables Leung tested will technically work, but if you connect them to incorrect hardware, you may end up with damaged equipment. That kind of failure mode is invisible to the consumer; people tend to assume that their chargers “just work” unless presented with dramatic evidence to the contrary.

The perennial problem USB Type-C is supposed to fix.

If you have a Chromebook Pixel from 2015 and want to check whether or not your USB Type-C cable contains the proper hardware, Leung has posted instructions on how to do so over on Google+. While Leung isn’t representing that these cables are a poor choice for anything but the Chromebook Pixel, the issues he’s identified would be common to any hardware. It’s particularly important that companies get these issues right, since USB Type-C typically requires these converters to function with legacy equipment. So far, there are too many companies dropping the ball.