I noticed this question has not been answered, and I am having the same problem. Please help...
It's the 15" 256GB storage with Touch Bar and 16GB memory. I'm not sure if there is something wrong with my battery or just a system glitch or something, but when I charge my MacBook it doesn't update the battery percentage until I go to click on the battery symbol in the menu bar, click on 'open energy saver preferences,' uncheck 'show battery status in menu bar,' and then re-check it.
So for a random example, it shows 90% but I've used it for an hour or two, and then it still says 90%. So I go through said process above, and it changes to a lower percentage like 30% or something.