Chosen Solution
I recently replaced the battery on this device. I did the calibrating of the battery properly (I think). When I leave the screen on unplugged, after an hour or so, the screen turns off. When I try to wake the device, I get the dreaded battery dead icon. But when i plug it in, the device will turn on and be a few percentage off from when I left it. I.e. battery at 66% device goes to sleep, screen turns off, try to wake, battery dead icon, plug in, wake device, battery at 62%. Any idea what is going on? Has this happened to anyone?
@raj14k - Well I do see a problem! SMC needs a hard reset as its still holding old battery info. Note the battery manufacturing date is a date older than the system manufacturing date! So carefully disconnect the battery and with nothing plugged in press and hold the power button to fully discharge the logic board. Now plug in your MagSafe charger your system should spontaneously boot up. Let it finish booting and properly shut it down. Now disconnect the charger and reconnect the battery. Let the system charge for a good four hours and while the MagSafe is plugged in. take a fresh snapshot of CoconutBattery.
You can use Mac fan control because sometimes they overheat and have some issues, also is the battery the original one?
