USB charging ports use the data pins to signal a request for more than 500mA. If you disconnect the data pins, how can any device (apple or anyone else) get more?
Couldn't charger have a current limiter set for charger load capacity and the device could just have resistance such that at 5V it would draw as much power as it can handle?
The obvious drawback would be that such device connected to charger without current limiter would burn it.
Then again I just burned a charger that had multiple sockets by connecting Samsung Galaxy Note 3 and iPad2 to it. It advertised via data lines capacity for 2A charging on all five USB sockets, but had total capacity of just 2.5 A.
I didn't know any single USB 2.0 port could serve more than 500mA regardless? Alas charging through the powergrid is way faster than through your laptop.
In any case I think that USBcondom is talking about is power hubs (i.e. custom hardware that could spread malware) and not specifically laptops.
The charge pins on a battery charging input could be used as a makeshift i2c to communicate with a smart battery chipset, thus communicating the same intentions ("hay! give me more!") without any additional wiring or need for access to the USB subsystem, while making use of the USB form-factor that's so ubiquitous today.
if lithium batteries weren't so problematic when overcharged you could float-charge everything pretty efficiently, then you wouldn't even need a management system.
Our current way of doing things is probably here to stay, though.
Since the whole concept of this 'usb condom' is to physically disconnect the data communication, re-designing the protocol to use the remaining pins as a data channel would defeat the whole point.
No, the point in the redesign of the protocol would be to eliminate the need for a 'USB condom'.
A data channel isn't a data channel. USB is designed to be widely used by many industries, as such the standard has provisions for many use-cases. A battery data channel is only for the charging equipment to communicate with the battery's chipset a limited amount of parameters. The data being transferred is incredibly limited, and can thus be sanitized easier when compared to USB.
A protocol designed in such a way would also be easier to test, as the scope of vulnerabilities would be much more limited than a general purpose data channel.
Regardless, it was merely a possible answer to
> If you disconnect the data pins, how can any device (apple or anyone else) get more?"
and really wasn't meant to be a valid product or concept. Just a fleeting thought.
