MacBook Air battery life/standby time destroyed by Lion!

I had the same issue with my 11'' MBA 2011. It would drain 10-20% of the battery while sleeping overnight. I took it to the Apple store and they had me do a power reset, same problem. Then they had me do a completley fresh install of the OS and drain and charge the battery completley. Still had the issue. Sent the machine for a warranty depot repair, they replaced the logic board, battery, io cable, and a couple of other things. Got it back, SAME ISSUE.... so I think the only conclusion left is that there is a problem with the OS , making something access the battery overnight. I think it is a "wake from USB" event...even though there are not USB devices attached. Hopefully Apple will address this.

Thank you Shadwig for sharing your experience and solution with pmset. I did some testing myself (MBA/Lion 10.7.3) and the results are not so clear :

As stated in in support link

http://support.apple.com/kb/HT4392

the MBA will not go to "standby" if connected to any external devices (USB, SD or Bluetooth). When on my desk, my MBA is connected with USB ethernet and hard disks, external screen and Bluetooth mouse.

So, first I tried the sleep+standby mode with and without external devices (initial pmset was hibernatemode 3)

Here are the results of the logs (pmset -g log)

Test1 : with external devices, hibernatemode 3

- Message: Sleep: Success - BATT 100 - Software Sleep

- Time: 26/04/12 19:57:14 HAEC

- Sleep count : 5

- Message: Wake: Success - AC 66 - EC.LidOpen

- Time: 27/04/12 10:19:16 HAEC

=> 14h = 34% battery drain

Test2 : without external devices, hibernatemode 3

- Message: Sleep: Success - BATT 98 - Clamshell Sleep

- Time: 27/04/12 19:50:15 HAEC

- Sleep count : 8

- Message: Wake: Success - BATT 92 - EC.LidOpen

- Time: 28/04/12 08:46:56 HAEC

=> 13h = 6% battery drain (much better !)

So then I changed the hibernatemode to 25

sudo pmset -b standbydelay 600 standby 1 hibernatemode 25

A test over 2 hours period was rather good (1% battery lost)

But over the night :

Test3 : with external devices, hibernatemode 25

* Domain: sleep

- Message: Sleep: Success - BATT 96 - Software Sleep

- Time: 28/04/12 19:44:22 HAEC

- Sleep count : 3

* Domain: wake

- Message: Wake from Standby: Success - BATT 75 - EC.LidOpen

=> 14h = 21% battery drain (no better than hibernatemode 3 !)

It seems there is no choice but shutdown or unplug all devices ?

The pmset -g log is quite convienient to follow the cycles, but it doesent identify the exact moment the computer goes from sleep to hibernate (or not).

Does anyone have a clue about the "Sleep count" meaning ?

Shadwig wrote:

Hey all,

I think the issue may have something to do with this support article: http://support.apple.com/kb/HT4392. MBAs are supposed to eventually go into hibernate mode where the computer's wake image is stored on the SSD. My 11" MBA came with OSX Lion so I don't know how it's battery life would be under Snow Leopard, but after using the "pmset" function in Terminal I noticed a discrepancy. "hibernatemode" was set to "3", which is the setting that tells the MBA to copy the startup image to the SSD but to also keep the image in RAM and power the RAM. Powering the RAM while in hibernate is contradictory to the support article, which states the image will be written to the SSD and power to the RAM will be cut. Reading through the "pmset" man pages I found "hibernatemode" "25", which tells the computer to write the wake image to the SSD and then power down RAM. This is in line with the support article. Perhaps Snow Leopard knew to set MBAs to "25" and Lion set MBAs to the normal portable default of "3"? I'm just guessing here. Either way, changing "hibernatemode" to "25" seems to have solved my sleep drain problems (0% battery loss over 4 hours), since while in hibernate power is no longer being fed to RAM.

And two other points. "standby" needs to be set to 1 to allow the MBA to drop into hibernate. "standbydelay" (in seconds) can be changed to have the MBA hibernate faster. The default is 70 min; I changed mine to 15 min (on battery).

The best thing to do is type "pmset man" in a Terminal window to see how pmset works, but this command should get your MBA sleep straight while on battery power ("-b" is for battery):

sudo pmset -b standbydelay 900 standby 1 hibernatemode 25

Once you execute this command you can type "pmset -g custom" to see your settings for both battery and AC power. Read through the man pages, pmset is a pretty cool function. And whatever you do, don't give "hibernatemode" values other than "0" "3" or "25"; according to the man pages you can really screw things up otherwise.

And one last thing to remember, per the support article the MBA will not drop into hibernate if it is still paired to bluetooth devices, so make sure to disconnect any before putting the MBA to sleep. I'm going to test this, though, because I like the convenience of bluetooth wake from sleep, etc.

I hope this helps out.

This solved my MacBook Air 11" battery drain ...thanks.

Just my own experiences, i m using an Samsung Galaxy S2 and using Kies. For any 1 who is using Kies of Samsung (like itunes for iphones). Please remove it.

My Fan speed had decresed from 6454 RPM down to 2000 RPM, greatly extended the battery life.

DIdn't work for me. Checked in Terminal with "pmset -g custom", and it all seems properly set up.