I was perusing the tech specs for the Switch hoping to find more information about the Switch's charging cables, and I came across this in the Pro Controler section:
Lithium-ion battery [CTR-003] battery capacity 1300mAh
The 1300mAh looked familiar, so I looked it up and it turns out CTR-003 is the code for the battery used in the original 3DS, the 2DS, and the Wii U Pro Controller. This makes it really easy to find a replacement battery (the Switch Pro Controller's battery is removable).
The Switch Pro Controller has an estimated 40 hour battery life, which is half as long as the Wii U Pro Controller's 80 hour battery life. While I think having NFC and HD Rumble are completely worth it, they must use up quite a bit of battery life.
One odd thing I saw was that the estimated charging time is 6 hours. I can't figure out why it would take so long, since even if you were charging the controller with a USB port in your computer, the 0.5A you would get from that should still charge the 1300mAh battery in 3-4 hours.
Anyway, I'm not sure if this has been posted before, but I thought it was interesting. Based on that charge time, though, I wouldn't count on the controller's included USB-A to USB-C cable to charge the Switch in a reasonable amount of time.
Discussion started at here by MetaRyan25