Same issue:
Updated my Macbook Air (early 2015) with the latest mac os 10.10.4 on 2 July 2015. I started noticing my battery started draining faster than usual.
Macbook Air Spec:
13" early 2015, i7 2.2Ghz, 8 GB
I use my macbook air for surfing, Netflix and work. Did not had a problem/issue with 10.10.2 and 10.10.3 OS, only after updating to 10.10.4.
And the worse and surprising part is seeing 80% battery from 100% from sleep mode (lid closed) for est. 7hr. Thats 20% battery drainage.
On the previous 10.10.3 os, I only saw 1-2% battery drainage in sleep mode for the same amount of hour under sleep.
Therefore, I decided to carried out my own small battery test couple of time.
Test 1:
Just to make sure its not any app that i have installed on my mac that is causing the battery drain, I closed and uninstall most user installed apps.
Next, charged up my mac to 100% battery and unplug my power and put my mac air to sleep for 8hr overnight.
Result 1:
Battery left: 89% from 100%
Thats 11% battery drainage just in sleep mode on mac os 10.10.4
Test 2:
Used Time Machine to roll back to 10.10.3, just before i updated to 10.10.4. Ran the same test condition accept without uninstalling user apps.
Charged up to 100% and put mac to sleep mode for 8hr.
Result 2:
battery left: 99% from 100%
Thats only 1% battery drainage just in sleep mode on mac os 10.10.3.
Conclusion:
There is some issue with the Mac OS 10.10.4 with regards to battery. Those of u who are having similar issue, just roll back to 10.10.3 (if u have it)
https://www.reddit.com/r/macbook/comments/3f03bl/macbook_os_10104_battery_drain_ issue/