Possibly the best mobile phone smart battery case in existence; evinced clearly by the Amazon reviews of it's predecessor.
I use mine daily - taking 4K video plus lots of photos and uploading them straightaway over mobile uses a lot of battery.
Why not have a battery case ... with a replaceable battery?
Why have replaceable batteries when the user could just carry several cases, and slip the delpleted one off, and the charged one on? I can't imagine a replaceable battery design that wouldn't add bulk, and likely require removal of the case from the phone anyway. Unless the case is made of leather, it's hard to imagine much savings in replaceable batteries. Also, how do those extra batteries get charged if not in the case?
Because batteries are smaller than entire cases; it requires less material and thus would be more efficient; and it would be more sustainable, since the battery case could last as long as the phone. Remember as well my original post was about using the iPhone for outdoors activities such as camping, so weight and size matter, along with not wanting to contribute unnecessarily to the pile of electronic waste we thoughtlessly produce.
I am on my 3rd battery cases for my iPhone 4S. The phone and its battery are fine, but now the third battery case is going bad. Thus, I'll have to buy a new battery case, when probably all that is wrong with the old battery case is that its battery is shot.
As for charging batteries, they could be charged from any USB port if they had a micro-USB connector. Replaceable batteries were common in mobile phones before planned obsolescence won over the industry and everybody started gluing things in place.
A better choice might be an external battery pack and a regular case. Most of the external battery packs available these days consist of one or more AA-sized or 18650-sized lithium-ion batteries, along with a very small circuit board, wrapped in a plastic shell. And they're easily available with capacities that dwarf those of the battery "cases" that piggyback on the phone (I have several, ranging from 3,000 mAh up to 26,800 mAh, for various uses). Then it all comes down to how much capacity do you need vs. how much size/weight are you willing to carry. And you don't have to carry them when you don't need them. I commonly carry a small 6,000 mAh battery in a runner's belt pouch when I go on long walks. I play a game called Ingress (game map overlaid on the real world, so you go walk around outside - it's where most of the tech for Pokemon Go came from) and everyone who plays the game much ends up with external batteries - I've met hundreds of players, basically all with external batteries (Anker is a favorite brand), and precisely one of them was using a Mophie battery case. These external batteries are as large or as small as you want them to be, the vast majority of their mass is the batteries themselves, since they use comparatively huge battery cells they'll last practically forever before you need to replace them (because you won't be charging them nearly as often) - if you really wanted you could pry the casing open, swap out the cells, and glue it back together, but chances are something better will have come along by the time these wear out.I am on my 3rd battery cases for my iPhone 4S. The phone and its battery are fine, but now the third battery case is going bad. Thus, I'll have to buy a new battery case, when probably all that is wrong with the old battery case is that its battery is shot.
A better choice might be an external battery pack and a regular case. Most of the external battery packs available these days consist of one or more AA-sized or 18650-sized lithium-ion batteries, along with a very small circuit board, wrapped in a plastic shell. And they're easily available with capacities that dwarf those of the battery "cases" that piggyback on the phone (I have several, ranging from 3,000 mAh up to 26,800 mAh, for various uses). Then it all comes down to how much capacity do you need vs. how much size/weight are you willing to carry. And you don't have to carry them when you don't need them. I commonly carry a small 6,000 mAh battery in a runner's belt pouch when I go on long walks. I play a game called Ingress (game map overlaid on the real world, so you go walk around outside - it's where most of the tech for Pokemon Go came from) and everyone who plays the game much ends up with external batteries - I've met hundreds of players, basically all with external batteries (Anker is a favorite brand), and precisely one of them was using a Mophie battery case. These external batteries are as large or as small as you want them to be, the vast majority of their mass is the batteries themselves, since they use comparatively huge battery cells they'll last practically forever before you need to replace them (because you won't be charging them nearly as often) - if you really wanted you could pry the casing open, swap out the cells, and glue it back together, but chances are something better will have come along by the time these wear out.
Agreed to some extent, but having a phone. cable and external battery pack can be bulky and sometimes if I am scrambling up a hill the cable comes lose. Actually usually I have a battery case plus an external battery. The Highlands of Scotland are not a good place to get lost, and I prefer using GPS to compulsively checking a map....
... I've got friends who do quite a bit of backpacking who carry a solar charging panel, that charges the phones while they hike, to some extent, as well as when they stop for lunch, etc. -- again niche use for most.