Since I've read that the Nexus 6P only "fast charge" protocol was 5V/3A over dual USB-C connectors, I was curious to find out.
And since I don't have any fancy equipment right now, this is using only software 🙂
– Using the provided charger and USB-C – USB-C cable:
Takes about 3A as expected
– Using a Samsung 5V/2A charger, which uses the same signaling as Quickcharge 1.0, and the provided USB-A USB-C cable (which is ridiculously short):
Takes about 2A, close to the maximum for this charger and definitely more than 1A which is the max for USB power without signaling.
So it stays reasonably compatible with most equipment dating from the pre-QuickCharge 2.0 era.
Either way, I'm not a fan of the solution Google adopted for the Nexus 5X and 6P charging.
The USB-C cables provided are annoyingly short. Since they have to carry 3A they're thick and inflexible.
Choosing a 50% higher current instead of higher voltages is inefficient: it requires thicker, more expensive, shorter cables.
And eventually, only 15W to charge a 3450 mAh battery is just not fast.
USB-C might be a the future standard but as it is on this year's nexus, it is not a very particularly convincing solution compared to Qualcomm QuickCharge 2.0 or 3.0