Everyone with a smartphone has experienced the pain of running our of power just when you need it most. Sure you can always carry around an external battery pack but always on batteries cases are the go to solution for many.
It seems everyone I talk to knows about the Mophie line of products but check out their Amazon rating (Juice Pack Air has a rating below 3) and you'll quickly realize that popular doesn't mean best.
In fact the comments you read on Amazon are telling. Most complain about the device breaking within a couple of months. My own experience mirrored these comments. I had 2 Mophie juice pack airs that broken in under 3 months (1 broke during an overseas trip which cause many headaches).
What I looked for when choosing a battery pack case
I wanted a real brand that offered a verifiable MFI Apple certification (no cheap Chinese knock offs)
An iPhone 5 has a 1440mAh battery and a 5s has a 1560mAh therefore I need a case that can fully charge my iphone at least once. You have to take into account the power loss due to design or power transfer as well (so my minimum mAh was 1700 and above).
Fast charging time for the battery and fastest charging time of my device.
The Winner is...
The best battery I have found is the Lenmar Meridien IPhone case.
Most cases offered battery capacities close to what they were advertising but Lenmar was the most accurate with its 2300mAh claim. It charged quickly itself and charged my iPhone (20%) within 15 minutes.
It is a one of the most slim and svelte battery cases out there and the price is extremely competitive at about $US50 on Amazon (link).
That being said, the buttons are a little difficult to access.
The other issue I encountered was diminished cell phone reception (less bars). Every case that covers the entire phone suffers from this issue. In areas with strong reception, this wasn't an issue but my office is a shielded building and I get 1/2 bars at best without a case. With the Lenmar (and other full body cases), I sometimes experienced dropped calls or reception dropping to sub-1 bar performance. (I use Telus by the way).
Overall this turned out to be a solid case with great performance and a few drawbacks. Having tested the Lenmar against the Mophie, uNu, Incipio and the Chinese knock-offs, I can say the Lenmar was the best. I was the slimmest and offered the best battery performance.
If you want or need a battery case for your iPhone 5/5s, get this one.