I just migrated an iPhone5 to an X. I'd like to put the iPhone5 into very long-term (probably 1+ year) storage. While I'll hopefully never need it again, I'd like to keep a back-up iPhone at the ready.
Given the chemistry of iPhone batteries, before putting it in a safe place for a very long time, should I drain the battery to 0%? or 100% charge, and power-off?
It is fresh off of a factory reset, so there is no data to be lost on the phone.