I've noticed that the battery on my 2012 MacBook Air seems to drain way too quickly while in sleep. When using the computer, it seems to drain normally but while asleep, it drains too fast. For example, I'll charge the battery to where its 100% and then unplug it while it still sleeps. Twelve hours later, I'll wake the computer and the battery has drained down to 81%. I've checked all the usual stuff...power nap off, nothing connected, etc. I took it to the Genius Bar and they ran a diagnostic test on the battery that reutrned normal. They reset the SMC but no change. I think something has got to be wrong as the battery shoud in no way drain 19% while in sleep, doing nothing...in less than 24 hours.