What's the maximum power delivery in Macbook Pro 2016, 2017 Thunderbolt 3 ports? I now this interface is capable of 100 watt, but I couldn't find what's the voltage/current capability for these machines through the USB-C ports (neither for the Macbook 12-inch 2015/16/17).
USB-C alone allows 4.5 Watts ( 900 mA @ 5 V ) and thunderbolt 3 improves on that greatly. 

According to Apple:


  MacBook Pro (15-inch, Late 2016) and MacBook (13-inch, Late 2016, Four
  Thunderbolt 3 Ports) can power two devices that use up to 15 watts,
  and two more devices that use up to 7.5 watts. It doesn't matter which
  side of your MacBook Pro that they're connected to—power is delivered
  on a first-come, first-served basis.
  
  MacBook Pro (13-inch, 2016, Two Thunderbolt 3 Ports) can power one
  device that uses up to 15 watts and one device that uses up to 7.5
  watts.


Thunderbolt Source: https://support.apple.com/en-us/HT207256

USB Source: https://support.apple.com/en-us/HT201163

NOTE: The above pages no longer contain the information I’m quoting, but you can view archived versions of them at: http://web.archive.org

The above specs are the same for the 2017 MacBook Pro models. The MacBook models only have USB levels of power and data available.