Hi there,
Given the fact that geocaching with the iPhone can quickly deplete the battery, please post any personal experiences or anecdotal information you have about using supplemental battery packs or Iphone External Battery (if you are new,please link to know).
I'm particularly interested in how much additional usage time you gained, whether you think it was a good investment, where you purchased it, and how much you paid for it.
I realize there are ways to stretch the battery life by turning off certain features and that not eveyone operates their iPhone or the geocaching app the same way,
so I'm more interested in relative time extensions ("twice as long") than actual hours.