I'm using an H600 with a MacBook Pro. It stopped charging and I didn't know why. I came across this gem:
So I took the USB wire out , tried it on a AC charger (didn't work) but then went down and plugged it into my PC - it started recharging as expected.
I'll update this to see if it completely dies again. I hope not - I've been having terrible luck with all my wireless headsets (Blueant died, Plaintronics died and my original Logitech did too).