Or you just cut two wires in a normal USB cable. No need to buy condoms!
I think the board is because some power sources might go "hey I'm leaking, there is no device but I draw power!" and cut it off, but I only ever heard about it and never encountered it. My USB ports nicely power fans without ever having a data connection to anything.
You can get a certain amount of power from USB without a data connection but to get more (which higher powered devices need to charge quickly or, in some cases, at all) you need to send a data signal to request it. So cutting those wires sort of works but will leave you with slow charging for some devices and no charging for a few others.
This is not true of most chargers. It is true of some devices that they look for the data lines to have some voltage rather than be left floating. There are 6 different 'standards' for this so you end up needing an IC like this[1] to detect which one the device is using.
Note: USB-PD changes the game a huge amount. You do need to speak USB to upgrade power there. But I've yet to see USB-PD in the flesh.
Actually this is true for MOST charger, the one that don't usually end up overheating and having a very short life spam. the reason why most people think this is the case is because when the device cannot be identify the charger default to the the data line shorted and to provide the typical power for which ti was design. https://lockedusb.com/pages/
For iPads and some other devices which require a 'signal' on the data pins, you would need an adapter to force the thing to charge. These adapters also act as a data condom, and are super-cheap:
Different manufacturers' devices expect different voltages on the data pins. A voltage which says "yeah, draw 2 amps" to an iPad may not indicates the same thing to a Samsung device.
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.
Yeah, i'll just tell my mom how to do that... one sec. It's a lot easier for me to go "hey mom, evil hackers can get you if you plug into an airport" "use this"
I think the board is because some power sources might go "hey I'm leaking, there is no device but I draw power!" and cut it off, but I only ever heard about it and never encountered it. My USB ports nicely power fans without ever having a data connection to anything.