[Sony Xperia S, Acro S, Ion] optimumpro:
My Xperia ION AT&T lasts for about 38-40 hours on WCDMA only and constantly active 2 sip accounts through Csipsimple (on WIFI and WCDMA), plenty of sip and gsm phone calls and internet usage. I am on T-Mobile and have all LT28i bands including T-Mobile's 1700 band and LTE.

Here is what worked for me:

First of all, I flashed generic deodexed 6.1.E.3.7 firmware, which is available on this forum. This took care of AT&T bloat. What I also discovered was that in AT&T firmware radio signal is weak. As such, when I went to *#*#4636#*#* and into phone information, I noticed that the signal was jumping all the time from HSPU to UMTS. That wastes a lot of battery power.. Second of all, I got rid of Google and some Xperia own bloat. I uninstalled or disabled (using Root Uninstaller) the following applications:

About PlayStation; All wallpapers I don't use; Android Live Wallpapers, Google back-up restore, Bluetooth Share, stock browser, bubbles, calendar storage, chrome browser (I recommend Dolphin--fastest and less battery consuming), com.android.providers.parterbookmarks, com.android.sharedstoragebackup, com.sonyericsson.appshare, com.sonyericsson.newsoftwarecheck, com.sonyericsson.warrantytime, connected devices, content sharing, cosmic flow, crashmonitor, devicemonitor, download music info, drm protected content storage, drmdialogs, stock email (kaiten mail is much better and has open gpg), enchanted forest, event stream engine, face unlock, all facebooks, friends music, gmail, google account manager, google backup transport, google services framework (you can still have access to google similar to that on a regular computer), hdmi (can enable if need to), help, learning client, mono, movies, musicFX, my uploads, network location (still have access to internet), neoreader, news&weather, nfc service (can enable if need to), notes (instead I use NoteCipher), OMA clients and services, play now, poBox Touch, protectedMedia Scanner, QC SEMC Service, R2R client, RRetail Demo, remote control service,

smart search, sony select, google play (I use Aptoid), Sound recorder (can enable if needed, otherwise, I don't want google to listen on my surroundings), swiqimasterreset, tags, talk, all timescapes, twitter and tv launcher, update center, bunch of verifycertificates dummy apps, wisepilot, and all google applications such as maps, earth and others. I use Sygic as main navigation. It is second to none in my view.

I also use LBGuard with phone ID availability disabled for all applications including system ones. As far as positioning, only Sygic is allowed to use it (prompt to allow only), I have a tight leash on all applications as far as internet access. Only Sip client, Skype, Dolphin and Aptoid (only when I use it) are allowed to access internet. I use adaway with Dolphin. It works like a charm. Even adaway is not allowed automatic updating (I do it manually once a month). LBGuard is also not allowed to access the internet (why?). I also use Total Screen Control with brightness set at 60% (it is enough for indoor lighting). I put a small widget on all screens, which allows to disable the setting in bright light.

And the result speaks for itself. Here is a screenshot attached.

Again, I have 2 sip accounts active all the time, plenty of sip and a little voice talk. I can access internet and everything that is available for a PC... It works for me.