Chosen Solution
Battery on 2017 MacBook Pro discharges way too quick. Geniuses can’t find solution Update (12/18/2018)
Does it discharge even when turned off? If not, then try to factory reset your OS and test a longevity of working with battery power only. If that does happen faster than in tests of this MacBook from internet-reviewers than you’ve got something wrong with either battery or power relay (and repair techicians are an idiots, is they didn’t find a thing, probably). If time that MacBook lived on battery is close to those from reviews, then it was some software that used a lot of CPU or GPU time (probably).
