Not sure i dig this item…it’s just as easy to carry a rechargable pack without wasting a disposable (read: ends up in our landfills) battery.
I don’t think these would be for everyday use. If I bought any of these it and a couple cheap batteries would go in the glove box. Set a reminder for a year or 2 in the future, and change batteries.
I still think it’s the answer to a question nobody asked! The batteries themselves don’t appear to be rechargeable. They only fit in the device which then plugs into a portable device which gives you two hours of additional service. Why not just carry a rechargeable battery extender as the other person suggested? Personally, I just have a second charged cellphone battery I carry at all times. One gets weak and I put in the other. The second battery for my phone was actually cheaper than the battery extenders although it can only be used for my phone!
I was thinking that these would come in handy when the sun is not shining and the solar charger isn’t charging. 
Does anyone know is rechargeable batteries can be used in these?
If it was a true emergency where you needed to call 911 or a tow truck and your phone was dead, then it would be handy to have one of these.
I think these have a place somewhere. not for me, but someone.
what other power source for your phone has a shelf life over several years? these have the benefit of not having to worry about them being charged if their replaced every year or 2.
I know my battery backups from anker wouldn’t hold that kind of charge.
your extra cell battery may last a while, I never thought of that. and not all cell batteries are replaceable.
The lithium primary cells used in these have a shelf life of 10 years. If you plan to charge one of those rechargeable packs and stash it for emergency use, it will be dead when you need it.
The battery may have a storage life of 10 years . . . but does anyone think that microUSB is going to be on their phone 3 years, 5 years, 10 years from now? The 30 pin connector for apple is already dead . . . I don’t think that I’m going to be keeping my iPhone 4 for terribly long . . .
Good point… except that I rotate my spare battery with the phone battery so that it is kept charged and I would expect that the owner of a rechargeable pack would keep their pack charged on a regular basis. Everything in life needs management… especially batteries in your emergency contact in times of need!
The UN mandated Micro USB as the universal standard for cell phone charging. It should still be in 5-10 years. Not saying they won’t change the design but USB should stay the standard for the near future.