Hello guys , I should sleep to go at work in 5 hours but i hope to help other people as this forum helped to solve mine.
I solved yesterday my issues included battery draining on tab s 8.4 clearing the cache from recovery and then when i dida factory reset i have no kore problems
my battery is awake from 24h and I still have 18%, no more issues with the processes.
About the first lunch I noticed (after any samsung and play store updates)the process com.phone.android went down at any incoming not answered call.the calendar process, and first the battery drain!
Now all goes well.and I can say to have a great phablet!
Inviato dal mio SM-T705