hello! so i have been having this problem with my MBP since I got it in late 2016. I use it plugged in for 99% of the time, but even while plugged in the battery drains. When the battery drains low enough performance begins to suffer. Ive had the logic board replaced once already but it is still happening. here are the specifics. I plug the power directly into the top left port.' I use the apple AV adaptor to connect to a second display and small usb hub on the bottom left port I use the the top left port for thunderbolt connectivity to a powered audio interface (apollo) I use the bottom right port for an external drive that runs off of bus power. Typically, the battery only starts draining when Im doing intensive work and using the second display. Is it possible that MBP can handle all of these peripherals? Ive wondered but haven't seen anyone else on any forums post this exact issue so its hard to be sure.