Thats great battery life!!Currently using this ROM on my SM-T705Y, with klimtlte version. I use this tablet to only read epub books, you can say I am using it as an ebook reader. I have turned off the adaptive display brightness and generally set the brightness to low, have not installed Gapps, and only using clean LineageOS and apps are minimal and limited to only ebook reader apps, Tachiyomi, Fdroid, DuckDuck Go Browser. Also, I am using the deathly version and have set the CPU frequency to a minimum of 100 MHz and max 400 MHz, and have increased the charging current rate. I have to say, the battery life now is outstanding. With a full charge and causal 1-2 hours reading, I get around 2-3 days of battery life. The screen on time is around 10-11 hours with only causal readings. This is probably one of the best tablets made by Samsung. 6-7 years and it is still going strong to date.