Thank you everyone for your intakes. I am not sure which one did the major job but they all worked. So now I am back on a good battery life again.
Special thanks to @will13am for mentioned the waklocks and exposed I was trying to avoid them since I didn't like to mess with them but now I had to deal with them.
There were indeed some issues with the system and I worked around it by playing on other apps and the mail app came from GApps project had the little default so I switched it with Gmail and completely disabled it for some synch issues.
This is the latest battery life on the 7800 mah it's back to two full days usage.
Thanks everyone for the great help.
@zhadj030, glad to help. I have always had some level of range anxiety and I pay very close attention to battery usage. These days, the cell chip is very energy efficient even at low signal strength. Wakelock is the remaining battery hog outside of screen being on. Rogue apps can cause huge wakelock problems. Interestingly google play services can be a real bad actor as well. I usually never reboot my phone, but do so religiously after a play services update. If I don't, play services will chew up power big time.
Do not worry, we all love to complain. To be honest, I had the same problem bylo Toronto. I reset the settings to the factory settings. At university I always connect to a local wi-fi. Although usually, I do not use the Internet in lectures. The best service in Canada (view site) helps me with my studies, here I buy research paper. By the way, can you use the Internet at a university or college?