Moonbase

Thanks to quite a lot of readers writing in, I now have a much better picture of what’s going on with charging my new phone. There are really two considerations when charging a device via USB:

First, not all USB ports are prepared to power devices (like charging phones) with high power requirements. There are various levels of peak power consumption defined by the USB specification, so it’s necessary to match the device to an appropriate USB host which can meet its specific power requirements.

Secondly (and this is evidently my real problem), many Motorola devices specifically check whether the USB port belongs to a Motorola-manufactured device; this is signaled by shorting certain pins, as documented here. Phones may also ignore this hardware check and charge from a regular USB port if the host computer has special software installed which responds with the Motorola “secret handshake”; a Linux machine running moto4lin appears to be sufficient for this purpose.