Is it s but on my laptop, or T2 managed charging generally I wonder. When left plugged in but asleep my 2018 model 15" is making what I presume is the "I'm 100%" charged chime every few minutes on a somewhat random schedule whilst asleep and left plugged in. it seems to happen about 3-4 times after first putting asleep over period of 5 minutes or so, before easing off, taking 5-10 minutes to next chime thereafter it seems. I can't believe it's meant to do this as it's incredibly annoying, especially when I'm trying to sleep! This happens on default power saving settings when left to sleep after display off, too, but does not happen if the machine is set to never sleep whilst plugged in and left display open.