Another thread on this subject:
https://www.mobileread.com/forums/sh...d.php?t=310518
I use this case:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
Open/closed on/off I see No Difference in battery. BUT Leave the WiFi On it Dies Quick. I suggest you turn Off the Wifi when not needed. My light is at 50 - 60% I keep the Color lights OFF.