So I bought the little 2200 mah energy to go Energizer pack a couple years ago, and that's worked well for a couple years but is wearing out. Looking for a new compact model similar... anyone have any recommendations? I've tried Anker models without much success (like many of the no-name brands they advertise one output and the reality turns out to be less). I really just need something that will get me one extra charge on the iPhone... with emphasis being on it's small size. Thanks!