Found a very well-done article about the problem still unsolved by apple since several years, Seems that this was beginning with OSX 10.8 (!) and was never really resolved (debugged) by apple ever since - perhaps someone knows more about this bizarre problem I (and shurely lots of other People) have to face... Perhaps a lot of people even don´t know about it.. and are wondering about their mac slowing down or fans going wild or batery time going down although not in excessive use... I found the problem just by chance because I wanted to protect the GPU of my 2011 and 2012 MBP´s by cooling more aggressively using MacFanControl. Although not using much of my CPU and GPU I was astonished about the fact that I faced after doing so often the fans going high rpm... and I found out that powerd was using up to 60-70% of the CPU (and so heating up the CPU) for just nearly NOTHING happening on the MBP... Found out that restarting the mac helped instantly, but this procedure ist *not_too_elegant* Plus: after restart powerd uses not more than 0,1% of the CPU but accumulates more and more CPU consumption and logically lots of energy from the battery for just nothing... Activity monitor was nearly always running before and now I will use it only if nessecary so... BUT: The article says that this will NOT completely stop the problem.. but change a big problem into a less important problem... http://www.planetarygear.org/2016/07/osxs-powerd-daemon-has-some-bugs.html ..