After factory resetting my phone, it seems to be back to normal... The battery is lasting for over 3 hour SoT on about two days off the charger, which I guess is fine for a phone older than two years still using the original battery...
The only thing bugging me now is Android OS... At home, which is where my phone sits most of the day, it seems to spend little battery, staying in the bottom of apps list in battery consumption screen, but when using my phone outside home, hence with no WiFi and under variable signal strength, it seems to spend more battery, but still less than Android System and, of course Screen usage, which is the top spender... Is this the normal behaviour on your phones???
And the same Android OS is using about 10 MB data (sometimes less, most of it from WiFi since I'm connected to it most of the day) on a day usage cycle, is this normal?