[Nexus 6P Accessories] Elnrik:
This is incorrect. The document you are referring to is a Compliance document used for testing and submitting devices to the USB IF devices for certification. The actual specifications are located here: http://www.usb.org/developers/docs/devclass_docs/BCv1.2_070312.zip

In the BC1.2_Final.pdf document contained in that zip, it clearly defines the parameter values for charging. See Table 5-2 for allowable currents. (Also, keep in mind, in this document PD = Portable Device, not power delivery.) It defines that a portable device shall not draw beyond 1.5A.

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In one of his posts, the Google engineer stated that BC2.1 only allows for 1.5A of current draw, but it was other proprietary protocols which allow for more current to be negotiated for and drawn. That's the big question for me - if BC2.1 is being used per Type-C specifications on Type-A ports, what protocols are actually being used when drawing more than 1.5A? That's the big missing link here. Because the phone clearly draws more than 1.5A when connected to QC and other dedicated charging ports. Without that information, we can examine USB specifications all day long and never get the correct answer.

I don't follow your reasoning here. You state that type-A port specifications limiting current to amounts less than 3A proves they can handle currents up to 3A? You then state that the specs try to prevent exactly that from happening. It's a confusing statement.

For clarification, no where in the 3.1 specs does it cover Type-C specifications. The Type-C specs cover Type-C and 3.1 specs. Further, the pullup resistor on the CC line is there to signal to Type-C devices what type of cable termination is on the other end. Nowhere have I found that this is designed to prevent damage to legacy chargers, as charging current isn't flowing over the CC line in on a legacy connection. Charging current is transferred over the VBUS wire(s).

Fixed a few things. You're confusing 3.1 for Type-C - or perhaps typing 3.1 when you meant type-c. I agree though that the charger's job is to sit there as a power supply, the device pulls current from it. BC2.1 is there to allow negotiation of current beyond the 500mA/900mA provided by base USB specs. The BC2.1 spec does show that currents drawn above max are supposed to initiate a shutdown, but I've yet to see this happen on certified USB type-a chargers, Type-C cables, and devices. Again, this leads me to believe that while BC2.1 spec is being used for negotiation of current, the negotiations are leading to current draws outside of the BC2.1 specifications - probably using proprietary protocols or specs.

There is also that Type-C is much more intelligent when negotiating current between Type-C devices. These new methods (CC/VConn in Type-C), from a physical wiring perspective alone, are completely incompatible with legacy ports. When it can't use a CC wire negotiation, it has to fall back to methods that are compatible with these ports such as BC2.1 or legacy 500mA/900mA charging methods.

Correct, but I have a slight issue with chargers fulfilling item 1 on your list. Protection mechanisms to prevent over-current or over-voltage situations aren't typically meant to be used 100% of the time the device is in use. It's like a "break glass in case of emergency" situation. I don't want to have to break that glass every time I'm plugging in. You can't un-break the glass. Or, if you rather, I'd prefer not to turn on my kitchen lights, then go outside and flip the tripped breaker, just to keep the light every time I want to cook dinner. Not only would that be annoying, but it indicates something is *wrong*. I don't want wrong, I want right.

If this amount of risk is acceptable to you, then by all means... continue. I don't, and won't.

It seems we both want to ensure people know what the risk is here so that they can at least make an informed decision - Which is cool, I dig it. We just disagree on the little details.