Hey guys. After buying MBPr last year this time, i immediately started researching how to preserve the battery health the best. I dont remember which threads i checked but i can say i have researched a lot. After many days past and tons of comments read I was convinced that best way is; -If you have the chance to use your MBP plugged in, do it. Plugged in is healthier (not to be used plugged in for months though) -If not emergency, dont let it past 20%, its not healthy to drain completely My roommate on the other hand, who bought the same MBP on the same day i bought, used it without any certain rules, sometimes plugged in, mostly on battery, often drains the battery fully. After one year of usage, here are the results. Carefully used 150Cycle = Hardcore used 450Cycle We mostly used his laptop in the living room thats why he has lot more cycles than i do, also as i said, i used it mostly plugged in thats another thing. As far as i know 1 cycle is a fully used battery. I mean If you use it until 50% and recharge it and using it again until 50% will increase the cycle count by one right? In any way, it should be showing just how much it is used on battery. If we consider the battery health is the same with these two usage (Carefully used 150Cycle = Hardcore used 450Cycle) result is quite disappointing, for me at least No more certain rules for battery usage anymore.