Sorcery?

In November last year the battery life of my Blackberry Priv started deteriorating rapidly. I could barely survive a day on a charge and it was getting worse. I got used to recharging it mid-day. Desperately looking for a replacement battery (still have not found one) and possibly another reason that might have been the root of the problem. I knew I could try to factory reset the device but during that busy time I just could not afford spending a couple of hours reinstalling all the apps.

And then magically on January 15th the heavy drain stopped. You can see it on the burndown charts. One shows the phone barely lasts 6 hours the other shows it can comfortably live for 27 hours. Barely a 450% difference.

The worst thing is I can not figure out what was the reason. It behaves now like it used to a year ago. Unfortunately the Android battery diagnostics do not help much.
I suspect the reason may be the LTE (4G) option. Desperately looking for a way to minimize the drain it has been on of the options I turned off. But I don't have enough data to prove this. So stay tuned. The investigation continues...