UPDATE for battery life after upgrade to Catalina
Hi guys, I am coming back with an update about battery life after 3 days of Catalina. As I mentioned earlier, right after the upgrade (installing Catalina on a separate APFS partition alongside High Sierra) my battery drain was quite high during use, but it turned out that this was only during the process of the OS indexing after the new installation.
Starting the second day, the battery drain during normal use is similar to High Sierra. Yesterday I used my MBP a bit heavier than usual (email, documents, installations, settings, youtube, data transfers, downloads, etc.) and managed to obtain a slightly better than 5 hour of battery life from 100% to 1 % (5:15 hours actually).
Today I used the mac only for surfing the net, email, watching youtube videos and using the MS Office apps (no photoshop, app installations or any resource-hungry activities) and my battery lasts even better times. With normal use it seems that I have juice for 7 hours, which is great for a 5 year laptop that it has been used heavily since day one. (my battery is at 384 cycle out of 1000 and it shows 87% of it's factory capacity)
However, I must say that I take good care of my battery since day one and I pay attention to have discharging cycles from time to time in order to keep a healthy battery. I have a powerful tool for this, an app called FruitJuice which overlooks my usage habits, calculates the discharging times necessary for keeping a healthy battery and reminds me to use my MAC also on battery from time to time. Otherwise I am tempted to use it mostly in clamshell mode, connected to power outlet with my two huge apple displays. Keeping a MBP always connected to AC power is the best way to destroy it's battery in a short time. I made this mistake with my previous MacBook Air.
As the battery drain during sleep issue, setting the sleep type to deep-sleep (25) turned out to be the fix for this. And I had a pleasant surprise to find that with deep sleep mode, Catalina wakes up very fast compared to previous OS versions, it is almost instant after opening the lid. So I close the lid with 100% battery and after 12 hours at the opening I still have 100%.
This you can obtain by opening Terminal app and copy/paste the following code:
"sudo pmset hibernatemode 25"
You cand verify in which sleep mode is your mac with this code: "pmset -g | grep hibernatemode"
Usually by default the sleep mode has number 3, so if you want to change back the sleeping mode to what it was initially, use the code: "sudo pmset hibernatemode 3"
I hope the above describes fix and solutions are helpful at least for a few of you guys, I decided to write down my experience because last time I had these kind of problems I spent many days looking for a workaround and it would have been very helpful if I could find these things fast and would have not lost so many precious days.
Regards!