This thing hosed my battery. Everything had been perfectly fine since Battery Update 1.2. Installed this POS and now my mac just shuts OFF with battery at 80%. Tried SMC & PRAM resets as suggested by some elsewhere to no avail. Take a look at Apple's discussion boards - there are many lengthy threads about this update, so much so that Apple is extending the Battery 1.2 replacement program to the 1.3 update whether under warranty or not. They are sending me a new battery at no charge. You have been warned! I will never again update my machine until at least a month has gone by and reports are 99% good. Shame on you Apple: your quality control and testing has gone to crap.