If I didn't have my 3200mah battery case I would have the same issues as OP. This is my first iPhone (regular 6S) and first phone with a battery case. On a typical work day I have plenty of power left when I go to bed (90% with spare juice in battery case). I only activate the case at 20% and it stops once the power draw is very low upon reaching 100%.
In anticipation I bought 3 spare cables and a number of regular cases but I don't need them. I only plug my phone in one time and that's while sleeping. Solved my charging OCD problem big time. And the phone is the right thickness and provides good protection.
In anticipation I bought 3 spare cables and a number of regular cases but I don't need them. I only plug my phone in one time and that's while sleeping. Solved my charging OCD problem big time. And the phone is the right thickness and provides good protection.