Big difference in battery life between /e/ versions

Hi all,
i have noticed big differences in the battery life of my OnePlus Nord (avicii) with different /e/ versions.
Just now upgrading from 1.6r to 1.7r on the stable branch doubled battery life from ~1 day to more than 2 days when i am not using the phone.

If i recall correctly 1.2 was also good and the versions in between had the shorter battery life.

Is there a way for me to see in a detailed way why it drains faster on one OS version than on the other?
Is anyone else experiencing anything similar?

As for me, also noticed sometimes quite big changes (also doubled time before) after updates since 1.0, but these never more than 1 week … may be up to the next battery re-charging ; note: I shut down my phone every night. My favorite hypothesis for this was simply that some brackground app (s) / service(s) (don’t know which) have failed to start at some moment, and were back to normal after a time … hence the battery charge lifetime.

I agree 1.7 seems now again to be a bit better than 1.6. But since old data in the cache of an app can cause battery drain of that app and also app updates can cause incompatibilities with the own cached data I’m not sure anymore about the impact of the OS. And because sending data is one of the most energy consuming processes it depends also a lot on what you do, where you are and what network you currently use (even if you do nothing, the device does probably a lot, especially the mail and messenger apps). In other words: it’s really not easy to guarantee comparable measurement conditions.