I've used [this rechargeable battery][1] for about a year, and it's fine. (I use it with various Android devices, not an iPhone). In case you cannot follow the link: it's described as "New Trent iCarrier 12,000mAh Heavy Duty 2A/1A Dual USB Ports External Battery Pack". [1]: http://www.amazon.com/gp/product/B003ZBZ64Q/

I've used [this rechargeable battery][1] for about a year, and it's fine. (I use it with various Android devices, not an iPhone). [1]: http://www.amazon.com/gp/product/B003ZBZ64Q/