[Galaxy S III General] sloepie:
I believe Google Now is for a big part cause of the excesive battery drainage.

I too had a big battery drain problem after my stock upgrade to Jelly Bean on my Galaxy I9300. Before the upgrade my battery in general lasted more than 40 hours, after the upgrade less than 24 hours. So I decided to install Omega V33.2 Jelly Bean 4.1.2 with all bloat-ware removed (standard Omega option).

Unfortunately nothing changed. I had the impression battery drainage went even faster.

So I started reading some articles about this subject and based on the information I found, I decided to close down Google Search (=Google Now) and Google Maps to see what would happen.

What happened next you can see on the attached screenshot (click underneath thumbnail) I made of my "Battery Monitor Widget" tool: After 37 hours I still had 66% battery left (usage = 0,58% /h, every vertical line is 1 hour)

Sure, I did not use my phone much, but my usage was no different from my usage before I closed down Google Search and Maps. Beside that, in order to find out which of the two is guilty of the battery drainage, I switched Google Search on again for 4,5 hours which resulted from the total battery drain of 34% in those 37 hours, in a battery drain of 15%.

I know, this looks rather unbelievable but this is what really happened. Let me explain what you can see on the attached screenshot underneath: At 28 November 15:23 hours I started measuring battery drainage with "Battery Monitor Widget" and immediately the battery started to drain fast (10% in 3 hours, red line down) After a few hours I decided to do my shutdown test. For that I needed a full battery, so the green line up is the charging of the battery.

On 28 November at 20:00 hours the battery was full. I rebooted and I started my test by closing down both Google Search and Google Maps. Than, from 20:00 hours to 13:30 hours the next day (29 November) my battery drained only 6% All this time the phone had been on Wifi only, but with Csipsimple voip and LBE Security Master running 24/7 in the background all the time .

Next, from 13:30 to 18:00 hours, I switched Google Search on again and I went to do some shopping together with my phone. I also switched from Wifi to 3G and immediately the battery started to drain fast again, though I did not use the phone at all (second red line down again) Than for almost 2 hours I sat in a cafe surfing for a short while using the cafe's wifi hotspot. Interestingly in those 2 hours I sat in the cafe on the wifi again, the battery did not drain much. Than I went home( with Wifi still on /3G off) and at 18:00 hours I closed down Google Search again. In those 4,5 hours the battery drained 15% (=3,33% /h).

What happened next is not clear to me because the next 5,5 hours the battery kept draining (with 3G off / Wifi still on. Not as fast as Google Search on in the 4,5 hours before, but still 9% in 5,5 hours (=1,6%/h). I suppose some other apps kept draining the battery? (That could only be the standard browser and/or Firefox which I used both?) So I did a reboot again and after that the battery drainage was on the 0.58% /h again as it had been from the start of my test.

I am not sure what kept draining my battery after I closed down Google Search, but I am 100% convinced that Google Search plays a bad role in the enormous fast battery drainage since the upgrade to Jelly Bean.

I don't know if it is a bug or that Google is doing stuff on or with my phone. But I think is outrageous that this happens. I am curious if other people can reproduce the same results and/or find out something more about this.