How should I tackle battery drain issues?? I'm fed up

Question

I'm fed up a bit for my Z3 C battery life. This is my second query regarding battery life.
Does keeping Mobile data and Whatsapp running ON even in standby mode drains the battery??
I usually get just 1 or 2 whatsapp messages in an hour or two.
My phone settings-
Always turned off my wifi/ bt/ nfc/ gps/ location tracking/ autoupdates etc. & everything you can think and suggest.
I use only stock custom wallpaper and no live stuff. No widgets. No sd card inserted. With only two homescreens with just 2 shortcuts on each screen.
Have disabled apps which I dont use.
Stopped services of apps which are no longer needed.
No auto sync enabled for any app.
Display brightness is at 30% all times.
I use only these 3rd party apps-
Status bar mini
Network monitor mini
Whatsapp
Greenify
My daily Z3 routine-
At night while going to sleep I turn off mobile data,  turn on airplane mode and turn on stamina mode. (12:30am - 9:30am)
Manually Force stop apps which are on. Use Greenify to exit/stop apps.
When I wake up the next day battery is down by 4-5%.
During day, phone runs in normal mode without any stamina activated. (10am - 12:30am)
The Low-battery mode seems useless as it does literally nothing.
Also, as soon as the battery is 100% charged and if I use phone for even 5 mins the battery immediately drops to 99%, so is this normal??
Even if I capture 5 photos in stock auto mode the battery drops by 1% or 2.
I reboot my phone once a week or in 10 days or when need arises.
Ram utilised is always 1gb. But I dont feel any slowness for any app or my phone usage.
So inspite of all this STRICT following what I get at the end of the day is just 1.2 days battery life.
Again I dont watch any movies or play games fearing my battery will deplete in no time.
So basically I'm using my Z3 as a battery monitoring unit and is 85% on standby mode. So when shall I use my phone the way it is designed for??? 
I have read people using it for occasionally playing games and watching movies, light surfing, calling and camear and it still lasts a good 2 days. So where I'm going wrong here?
I use 2G/edge network as 3G isnt available for my operator in the city I reside.
Charging the phone to 100% from 14% takes 3 to 3.5 hours.
I have already repaired my phone using Sony pc companion and also did a factory reset as well but this issue has been haunting me.
Sony center says the battery doesnt need any replacement as its still healthy and so is my device.
The phones service menu also reports battery status as Good.
I dont know when is Lollipop gonna be out for Z3 but I fear updating to Lollipop as it may pose more serious issues than doing any good apart from usual GUI tweaks & updates.
But just wish that lollipop brings in more relief to Z3 batteries and operations.
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Answer 1

Hi all,
I dont know what topic to choose Got them all:
I was looking around and tried a lot of tips concerning the battery drainage, no luck , 
but then I noticed other issues as well
I tried to send a mail to support but, some how it is not working today: tried different browsers, even different computers.
NOT here to talk bad, complain or talk down on this product, I know the phone in  working condition,
from my house mate and it is what they promise. I just dont know what to do and a bit frustrated and lauged at by my house mate.
I am posting, may be you guys have some answers, solutions or experiences.
But I think I am just unlucky to have a black sheep of the production.
My Firmware : 23.0.1.A.5.77
My issues.
- Battery Drain
- Screen isseus
- And reception issues 
**Battery Drain**
I wake up 06:00 get it from the charger got to work when I come home 18:00 i got 15% left.
I actually can see the percentages going down while scrolling my emails.
ow beginning I work in support myself, I waited for an
- Waited for Updates
- Installed the update
- Un installed apps.
- Configured stamina almost so tight that most of the apps except email where online
- Did a factory reset twice
1) First time start using it as normal, with less apps, still same performance maybe
     3% better, but that might be because i didn't used it so much of the less apps
2) Second time Factory reset - I got a 2, full days out of it:
     - No Apps Installed
     - No Wifi
     - Didn't use it at al left it on my nightstand
     - No data traffic
     - 3/4 screenshots
     - No Phone Calls
Well what is the use for a (premium) smartphone if you leave it on your nightstand?
When I start using it at the minimum installed:
- 2 email accounts (Gmail and company one)
- Facebook
- Spotify
Check it out:
!!This after the 2nd FACTORY RESET Yesterday!!!
Screenshot from this morning on my way to work
(to be fair left it with 100% unused at home and still 2 days and 3 hours)
Ok the next picture is on my way home , didnt use it since no apps installed and busy at work (this is about 12 hrs later)
Installed Spotify listened about 30minutes over 4g
18 hours left ? Quick calculation dat is 21 hours missing (33 hours in total)
Next installed facebook , some mail accounts, whatsapp, apped a couple of people that I am available again
45 Minutes later: 8 hours gone.
What do you think? Is it me? Or is there something wrong?
** SCREEN PROBLEMS **
I tought I noticed a couple of glitches with the screen, like little flashes,
but was not sure, I kind of found the use of the screen suspicious while monitoring the battery (50%)
al the time even if it was home doing nothing the whole day.
The  the Bouncing touch, i experienced that also but not constant, there is another topic about that here.
Things I didnt worried about untill : I was looking around the battery menu,
and descover the usage graph screen, when I went in to it i noticed a little falsh and a lag.
and then I had a little heart attack: screen broken , dead pixels what is it.?! BUT ONLY on yhis screen,
no problem with it BEFORE the factory reset:
TAKE A LOOK, AND ALSO NOTICE THE GRAPH GOING DOWN ALMOST IN A STRAIGHT LINE,
screen shot a minute later as the 3rd screen shot of battery drain.
CHECK THE BOTTOM OF THE SCREEN , IT LOOKS CRACKED RIGHT? IT ISNT!!
** CONNECTION/RECEPTION PROBLEMS **
I kind of noticed , isseus , but wasnt bothered that much, only while analyzing the battery that was my main concern.
I noticed I had always less reception than others same room/place same provider (VODAFONE IRELAND),
maybe that was an factor draining the battery, but it was not like there was really low signal just one bar less then other
people an the other Z3 here in the house.
What did noticed , and I was willing to wait for an firmware update for it, It kept losing 4G connectivity;
it flipped to 3g for a bit and the stays hanging around H and Edge.
WORKAROUND restart the fone and with no problem back on 4g but after a while and not moving;
4g drops again to either H or Edge. (Mind Vodafone has the biggest and strongest 4g network at the moment here in Dublin)
So now I dont know what to do, I kinda bought the fone for my holiday (in 3 weeks).
 - Is it serious enough that Sony will replace it? Since opening it up an closing it, will lose waterproofing
 - What else will they expect from me to do / trouble shoot?
 - How long will a solution take? Sending the fone back etc.
And finally other people reconize these isseus, and especially like me at the same time?
Thanks in advance For your Feedback (if Any).
I will try to mail support again now, and hope the website works now.
Eddy.