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Comment by cydonian_monk | Hacker News Reader

I'm seeing the exact opposite, but for a different reason. On Lion I could put my MBP to sleep and only lose about 5-10% of the battery over 8 hours. Now on ML I lose ~40%, with nothing running. I turned off location services today to see if that's the culprit.

As for actual on-battery use - yes, the battery life is noticeably improved over Lion.

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Are you running Power Nap on battery? Also are you leaving USB items plugged in?

On Lion at least I noticed that if I left my USB HD in, and closed the lid on battery it killed it, every time. There was an Apple Support thread confirming that.

Nope, nothing plugged in. No power nap. WiFi is turned off.

I've got some time next week to look at it, and intend to get to the bottom of it. It's annoying to not be able to carry around a sleeping laptop for a day without it dying.

How I found that was happening for me was looking in Console for Wake and Sleep strings, best of luck.

Apparently, having an external disk mounted prevents the system from going into some sleep modes, which will kill the battery:

http://support.apple.com/kb/HT1776

That could quite possibly be it, as I don't always unmount my fileservers when I leave home. I'll make sure to do that from now on, and might just write a script to handle it. Thanks.

I wonder if this same issue would crop up with the Amazon Cloud Drive.... It's not much more than a CIFS/NFS mount.

Is Power Nap on? (The switch is in the Energy Saver pane)

13" MacBookPro - Power Nap is not supported. Though it is certainly behaving as though it's turned on (power-wise).

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