The new MacBook Pro charges very, very quickly, 10 to 80% in 20-30 minutes by my estimation.

I can count on running off the battery all day as long as I can get it plugged in while I fetch a sandwich for lunch.

Do you know if it will slow charge from a low power usb power source?

If I plug mine into a 2 amp usb A charger it says that it is not charging, but does that mean it is drawing zero watts, or only that it is only drawing 10 watts? It would be nice to charge it overnight if only a phone charger happens to be around, or even just slow down the discharge rate while using the laptop.

It does slow charge, i use my external Anker Powercore Plus battery pack with it, while its not able to charge it while running because the MBP draws more Power than the Anker Battery can output it EXTENDS its battery lifetime very noticeably.

While that'd work, I'd advise against it as I feel like that'd needlessly heat the battery and reduce its life.

If that were true, wouldn't it be the job of the computer's battery management system to make sure it didn't happen?

Forcing user to learn all kinds of magic rules for how to "treat their battery" seems very old-fashioned and strange.

No, when providing supplemental power the battery current is lower and therefore has less heating. This will extend the life of the battery.

It does -- I travel with a 12" Macbook and the Google 15W USB-C charger. Take about 3 hours to charge from <10% to full.

Where would one buy this charger? Would be great as a travel charger if it works well, I currently use my iPad charger but a 50% power boost would come greatly appreciated.

18w version is here https://store.google.com/product/usb_type_c_18w_power_adapte...

I've charged my 15" Touchbar MBP with a 2 amp charger and a USB-A -> USB-C charger. Both used it for overnight charing and while plugged in (when using it plugged in it wouldn't draw battery but it wouldn't charge it either, maybe even drawing battery very slowly).

The reason why USB-C (with Power Delivery) is connected to fast charging with phones is that it allows more power to be transferred via cable than previous USB charging standards. For Notebooks this is not necessarily true, as there was no limitation for power delivered to the notebook before.

What you have to consider with fast charging is that it degrades the batteries faster and produces more heat.

iPad Pros fast charge from the USB-C adaptors.