Yesterday I replaced the battery on my MacBook Air 13" mid 2012 with a replacement from a reputable battery reseller, and performed a "calibration". Today I charged it up to 100% and used it during the day, up until 3.30 pm. At that time the battery level was at 38%. I simply left the computer on and turned off the external screen, as I always do, and presumed it would go to sleep, as it always does.
I came back 3 hours later, and the battery was at 0% and OSx had actually shut down, so the computer booted when I connected the charger (after having tried waking it up several times using the power button and touchpad).
What could have happened?
It usually turns off the screen and sleeps when I just leave it, it's set to sleep after 10 minutes in the Energy Saver settings. It was not connected to any WiFi after I left it (I'm sure of it since I'm using my phone as a WiFi hotspot, and I took my phone with me).
The replacement battery seems good, it displays a "maximum charge" of 7346mAh in CoconutBattery, which is more than the advertised 7200mAh. I'm getting roughly 5 hours of WiFi usage on it (the old original battery would give me 2-2.5 hours tops, and it was down to 3800mAh).
Here's the power log from just before I left the computer at 3.30pm, until now:
	
	
	
		
	
		
			
		
		
	
				
			I came back 3 hours later, and the battery was at 0% and OSx had actually shut down, so the computer booted when I connected the charger (after having tried waking it up several times using the power button and touchpad).
What could have happened?
It usually turns off the screen and sleeps when I just leave it, it's set to sleep after 10 minutes in the Energy Saver settings. It was not connected to any WiFi after I left it (I'm sure of it since I'm using my phone as a WiFi hotspot, and I took my phone with me).
The replacement battery seems good, it displays a "maximum charge" of 7346mAh in CoconutBattery, which is more than the advertised 7200mAh. I'm getting roughly 5 hours of WiFi usage on it (the old original battery would give me 2-2.5 hours tops, and it was down to 3800mAh).
Here's the power log from just before I left the computer at 3.30pm, until now:
		Code:
	
	2016-07-28 15:11:54 +0200 Assertions              Kernel Idle sleep preventers: -None-         
2016-07-28 15:26:45 +0200 Assertions              Kernel Idle sleep preventers: IODisplayWrangler         
2016-07-28 15:26:45 +0200 Notification            Display is turned on                                                                   
2016-07-28 15:26:45 +0200 Assertions              PID 109(hidd) Created UserIsActive "com.apple.iohideventsystem.queue.tickle" 00:00:00  id:0x0x9000004ef [System: PrevIdle DeclUser kDisp]         
2016-07-28 15:27:15 +0200 Notification            Display is turned off                                                                   
2016-07-28 15:27:15 +0200 Assertions              PID 205(coreaudiod) Summary PreventUserIdleSystemSleep "com.apple.audio.AppleHDAEngineOutput:1B,0,1,1:0.context.preventuseridlesleep" 02:58:13  id:0x0x1000003da [System: PrevIdle DeclUser kDisp]         
2016-07-28 15:27:15 +0200 Assertions              PID 109(hidd) Summary UserIsActive "com.apple.iohideventsystem.queue.tickle" 00:00:30  id:0x0x9000004ef [System: PrevIdle DeclUser kDisp]         
2016-07-28 15:27:15 +0200 Assertions              Kernel Idle sleep preventers: -None-         
2016-07-28 15:31:45 +0200 Assertions              PID 109(hidd) TimedOut UserIsActive "com.apple.iohideventsystem.queue.tickle" 00:04:59  id:0x0x9000004ef [System: PrevIdle DeclUser kDisp]         
2016-07-28 18:09:31 +0200 Assertions              PID 205(coreaudiod) TurnedOff PreventUserIdleSystemSleep "com.apple.audio.AppleHDAEngineOutput:1B,0,1,1:0.context.preventuseridlesleep" 05:40:28  id:0x0x1000003da [System: No Assertions]         
Sleep/Wakes since boot:1   Dark Wake Count in this sleep cycle:0
Time stamp                Domain                  Message                                                                        Duration      Delay   
==========                ======                  =======                                                                        ========      =====   
UUID: C77537CF-E2AA-45E3-A114-C94E5EC6B8BF
2016-07-28 18:09:32 +0200 Sleep                   Entering Sleep state due to 'Low Power Sleep': Using Batt (Charge:0%)         
2016-07-28 18:09:34 +0200 PM Client Acks          Delays to Sleep notifications: [com.apple.apsd is slow(2278 ms)]         
2016-07-28 18:34:33 +0200 Assertions              PID 109(hidd) Created UserIsActive "com.apple.iohideventsystem.queue.tickle" 00:00:00  id:0x0x90000014b [System: DeclUser kDisp]         
2016-07-28 18:36:04 +0200 :Showing all currently held IOKit power assertions
Assertion status system-wide:
   BackgroundTask                 0
   ApplePushServiceTask           0
   UserIsActive                   1
   PreventUserIdleDisplaySleep    0
   PreventSystemSleep             0
   ExternalMedia                  0
   PreventUserIdleSystemSleep     1
   NetworkClientActive            0
Listed by owning process:
   pid 602(softwareupdate_notify_agent): [0x00000069000b01c8] 00:00:18 BackgroundTask named: "com.apple.softwareupdate.NotifyAgentAssertion"
   pid 415(UserEventAgent): [0x000000430001019f] 00:00:56 PreventUserIdleSystemSleep named: "CDSystemMonitor: delay notifications on switch to AC power"
    Timeout will fire in 9 secs Action=TimeoutActionRelease
   pid 47(UserEventAgent): [0x000000430001019e] 00:00:56 PreventUserIdleSystemSleep named: "CDSystemMonitor: delay notifications on switch to AC power"
    Timeout will fire in 9 secs Action=TimeoutActionRelease
   pid 47(UserEventAgent): [0x0000002b000b0156] 00:01:20 BackgroundTask named: "com.apple.periodic-weekly"
    Created for PID: 394.
   pid 47(UserEventAgent): [0x0000002b000b0154] 00:01:20 BackgroundTask named: "com.apple.SoftwareUpdate.Activity"
    Created for PID: 241.
   pid 47(UserEventAgent): [0x00000021000b0148] 00:01:30 BackgroundTask named: "com.apple.mds.2"
    Created for PID: 68.
   pid 47(UserEventAgent): [0x0000001d000b0140] 13792:35:19 BackgroundTask named: "com.apple.metadata.mds.power"
    Created for PID: 68.
   pid 47(UserEventAgent): [0x00000017000b0139] 13792:35:25 BackgroundTask named: "com.apple.metadata.mds_stores.power"
    Created for PID: 225.
   pid 109(hidd): [0x000000210009014b] 00:01:30 UserIsActive named: "com.apple.iohideventsystem.queue.tickle"
    Timeout will fire in 575 secs Action=TimeoutActionRelease
No kernel assertions.
Idle sleep preventers: IODisplayWrangler