I have a 2017 15inch MBP. I noticed recently that the battery life has been very erratic and doesn't last me as long as it used to. It even drops from 30% to 10% or below in a split second sometimes. The cycle count is 147 and Coconut Battery, BatteryHealth and Fruit Juice have all reported a battery capacity as 77%. Apple's system report says the battery is "Normal" and the restart while holding the "D" key diagnostic test returns with no errors. Has anyone experienced an issue like this?