Happy new year for all!
Sorry for my poor english, i dont speak too good..
I have a CatS60 and i have not problem with the akku life.. I charge only 1 times in a week and if i look it now : 36% - 4 days left. I use it for hard work, 2 sims, daily 1-2 hours speak time, 30-40 calls, sms, mails. etc.
I think the problem is not with the phone self, it have a basis android version and Bullit develop only the hardware, he customize not the firmware for phone.
Google is the sinner for this huge akku-use, he want all know about you, if you block the many google apps, background transfers, etc., you can win more akku time.
With this setting if i charge to 95%, the phone shows me 8 days left (not only for cat, but for all my android phones):
-only 2 G on both sims, if you need mobile data, switch manual to LTE
-blocking, deleting all google apps what you not need, music, movie, clock, calendar, etc. The wake-up clock used my battery life 50% on 1 night!
-search other free apps for substitute, other photo gallery, camera app, etc. but dont google, what send your data for servers, all times when you swich on the wifi.
-switch off background transfers, auto-sync with gmail, contacts (make it manual if you need), switch akku-save mode on
-close always the apps manual after use with the right button
-switch off screen rotation, if its on, the sensor eating your akku
-i have a matte protector on the screen, better for navigation in car and the touch sensitivity is much better
Its a very good phone, i have problem only with the camera quality and the app toolbox, i think this app is a backdoor from Bullit to phone, i hope later with a root i can delete it.