The box itself was designed in SketchUp and printed on a Printrbot 3D printer. So what happens when a device pulls more power than a hub or charger expects? What does a graceful or non-graceful failure look like? We wanted to know. The USB-IF has a standard for doing this called the Battery Charging class, but the big guys like Apple, Samsung, and others don’t follow it universally. There are many proprietary methods devices use to detect “their charger” and start pulling higher amperages. Hubs and chargers are supposed to fail gracefully if a device pulls too much.Īnd it’s all gotten more confusing as USB has become a primary way of charging phones and tablets. This is to avoid voltage drops which might knock other devices off the bus. Devices are supposed to follow certain rules, like pulling no more than 100mA unless they configure up to a higher amperage (500mA for USB 2.0 and 900mA for USB 3.0). Devices can pull as much power as they want, but there are consequences. It’s natural to assume that hubs “deliver” a certain amount of power to a device. USB power and charging issues are surprisingly complex.
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