[XDA Assist] zulugulu:
Dear XDA experts,

It seems I have a typical problem for most Samsung Galaxy S3 I9300 users. I've been testing my phone's battery capacity on two different batteries, and four custom roms, yet something leeches out their power incredibly fast.

I've been deeply investigating the issue across the web, with no prevalent solutions that worked. Below I will describe exactly what my problem is, my specs, and what I've done to this point.

This will be my first post. I'm only doing this because I want to bring BetterBatteryStats data into consideration, without just speculating "do this". Please have mercy on my soul - I really appreciate all the stuff on the forum, and I wouldn't like to violate any rules.

Problem

My Samsung Galaxy S3 I9300 drains my batteries as a vampire, regardless of what I've tried. Just to give you an example: the phone loses 6% out of a 100% in just 40 minutes of standby, while being optimized, with no "lost signal" search processes. Without charging it twice a day, the S3 remains mostly unusable.

Purchase and Specs

I'm its second owner. The previous one sold it to me through an auction site (he was changing to S4). The phone seems legit. Mint conditions, little or no scratches visible. The system was factory wiped, and later it turned out that it wasn't flashed before. I also got original Polish carrier boxing with instructions, and equipment.

Note: The guy didn't handle the receipt to me, and I don't know if there's still warranty on the phone. Servicing might not be an option.

System:

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www (dot)mediafire(dot)com(slash)folder(slash)wfb1spe9ez9al(slash)xda_S3_thread

SentinelROM 6.00

3.0.64-CM-gfab9e4c Kernel

Android 4.4.2

Factory battery EB-L1G6LLU 2100 mAh

Second battery M-Life ML0373 2300 mAh 8.5Wh 3.7v Li-ion

Normally, Bluelight Filter and GoLauncher EX Prime are the minimum that I have in the background.

What I've already done

Rooted my S3 with CM Autoroot

Installed CWM Recovery 6.0.4.6

Always did a factory, cache, and dalvik wipe

Tested CM11 NIghtly from 09.12.14

Tested CM10.2 Stable

Finally flashed SentinelROM 6.00 4.4 KK

Debloated my phone - not syncing, no tracking

Disabled "All, that's Google" #notonmywatch

With every new ROM, I've been optimizing settings and tweaking the CPU to ONDEMAND. Also, same time I've been running Go Power Master and Greenify. That covers nearly everything people were recommending in the many threads I've visited.

Weird facts

Phone can lose 6% in 40 minutes after charge while idle

Writing an sms can take as much as 10% of the battery

It seems odd that the S3 can fully charge in just 1h on both batteries

When trying to discharge my phone, it deadlocks below 4%, lasting unusual 2.5h when used

Screens

I've been monitoring my phone for a day with BetterBatteryStats while I had Greenify hybernate some apps. Obviously, I've seen an improvement in the performance, but it just seems not right. There's a lot of pics here, but I hope that someone can spot a tracing app, or some other spying tactics, because I just can't explain what's on.

[Cannot upload - all files in a MediaFire folder. Please look over there. Just add the missing characters]

www (dot)mediafire(dot)com(slash)folder(slash)wfb1spe9ez9al(slash)xda_S3_thread

That's all I have for now. I think it would be a great favor to everybody on XDA to finally crack the case. I'm open to suggestions, and I can run tests on the S3 and provide results here.

Last question

Could someone recommend the best ROM and kernel for energy optimization?

Thank you, and good luck.

PS: Imagine playing Watchdogs with Aiden having an advanced S3 phone... Wouldn't happen :D