The Apple iPhone 6S smart battery case review


Junior Member
Jul 6, 2018
The Smart battery case was launched in late 2015, triggering a controversy like many Apple releases. Deemed as an overpriced, ugly and low capacity first party alternative to a classical “mophie” it spawned “hate” on forums, on video even in news. The famous hump became an example of Apple losing its famous design mojo for making a product should never be released yet never forgotten. This went so far, that even Tim Cook made public statement in defence, if I remember correctly.
While initially I was excited for a first party battery case as one of the most popular and exciting sort of accessory ever made, I put it on hold because of the universal negativity. I waited for the reviews, but never found anything that would answer all the questions - most of them only commented on low battery capacity and never did any controlled battery test.

So with over a year of experience I decided to make a review by myself.

Design and ergonomics

The case is made from soft and rubbery silicone, with microfiber lining on the inside a setup known from other Apple cases. But the inside contains hard plastic and steel acting as housing for battery itself making the case surprisingly sturdy, yet relatively light for a battery case at about 100g. There also a thick lip around the perimeter. In combination with a good screen protector the setup feels more like a phone built for sustaining damage than delicate aluminium wafer. And it did sustain countless drops on hard surfaces, with just some rubber peeling off. The case strongly attracts oils and dust but can be wiped clean (if you like to torture yourself).
The case contains microphone and speaker passthrough on the bottom chin as well as some power circuitry. Over longer time usage, dust readily collects in the sound guides. Then there is a small LED for indicating charging in the inside and a female lightning on the bottom. The phone slides from the top of the case which is the only flexible part and sits on a lightning connector on the bottom. This also means you could easily snap the connector if you just jammed the phone in at an angle The buttons are covered by silicone sides and still feel tactile, while mute switch passes trough.

The phone is converted into sort of a brick. While iPhone 6 might be hard to notice in pocket sometime, you are not going to miss this thing. Also the size combined with relatively grippy silicone, makes it much harder to slide the little abomination in and out of your pocket.
The fit for an iPhone 6 was not perfect, the phone could rock left to right ever so slightly, but I attribute this to the case being for the 6S while a 6 is ever so slightly smaller. Tucking a sheet of paper under and around the phone made the fit perfect. Releasing the phone requires bending the top and pushing the phone trough. This requires quite bit of force at first to disconnect the lightning connector, which is a problem because glass screen is slippery and LCD takes the pressure. Pulling the phone from the top requires quite a bend to the top part, which after months caused some deformation to the microfibre lining. Still the manipulation with the case is quite easy, much closer to regular case than a battery one. You could have both colors and pick one as you feel (or how much power you need).

The Tech and experience

The cover contains battery of 7,13Wh (1877 mAh). In comparison to third party cases that often have 10 or 12Wh capacity this is more of a “juice pack helium” than a full blown power-bank sticked to a phone.
The reason for the controversial shape is ergonomic. While holding the phone normally in hand, or in landscape, hands make virtually no contact with the bump. Only reminder is the high weight. The “tumor” also prevents blocking wireless antennas with conductive battery mass and the exposed parts actually include some “passive antennas” to actually boost reception. This opens up a question, if even an empty case gives you a bit more battery life ? While I used the phone even with empty case I could not notice a difference, possibly thanks to god coverage in my area. But I has seen a single review that tested the case with LTE heavy workload, and the case managed over 100% improvement in runtime. Is that antenna at work there ?
The most interesting thing is in how the case actually works. The moment a phone is attached, the case starts charging it until full. A full battery case could fill up an empty iPhone 6 to 75% which I see as a relatively good conversion efficiency. The speed of charging is pretty much identical to 5W output of iPhone charger. If the phone is fully charged, case is directly drained until it is empty. Battery percentage for both the case and phone is directly shown in the battery widget, while battery icon in status bar becomes useless, only shoving a full, charging battery while the case holds.

Charging the case is a “how it should be” experience compared to other battery cases. In a sentence it can charge the phone and itself simultaneously. If you use the standard 5W charger, the phone will eat up all the power, until it starts to trickle charge. Then the power overflows to the case getting you something like 20 bonus % by the time phone fully charges. But the case also supports full blown 12W iPad charger. Not only you get an iPhone charged faster, the remaining power goes to the case. The result is a 200% charge in about 2 hours, with case usually charged up faster than the phone.
This “quick charge” actually happened before iPhone 7 implemented 10W charging and it looks like some battery tech for the 7 was tried in the case itself. When charging just the case with the 12W charger, it could get 27% in 20 minutes and full charge in mere 76 minutes. While full charge could be skewed by how the case reports its charge state compared to the iPhone it was the fastest charging time for an Apple product at the time.
Regarding thermal emissions, the case itself only heats up in a small area in the corner. The phone itself does not overheat even while fast charging. During heavy usage nothing like unexpected throttling was noticed, probably thanks to using relatively low peak power iPhone 6 and steel case frame that conducts heat away. The white case is actually very good when using the phone as GPS as it seemingly heats up an order or magnitude less than metal phone under sunlight.

The flaws of perfection

In an ideal world the case would only hive as much power to the power as it needs at the moment this isn’t that case. While way better than regular approach of a powerbank, the case does not deliver power ideally. Charging phone to 100% is useful as you can put the case down anytime you want. Charging the phone consistently is not. You would expect the ideal case does not charge the phone after reaching 100%. The smart battery case definitely tries to lower the power output to minimum with a fully charged and idling phone. But still the static leakage is about 2% per hour, which does not seem like a lot, but it essentially makes the case drain by itself in about 2 days. This was reduced by a software update to iOS 11 and I would say it’s about 30% per day now. This means the case will have almost no effect on the standby time of your phone. But if you use your phone heavily and using a lot of power it gets a lot closer to the theoretical 2X longer battery life. It’s much better fit for a busy gaming session than a week long road trip.

When you charge an iOS device it first uses all the power it needs to power itself, then sending the rest to the battery to charge it. This battery charging is linear and then starts to slow down to a slow crawl to 100%. The case behaves differently. While phone happily shows 100% under most situations, under heavy load it starts to discharge. And it looks like the amount of power the phone can drain from the case depends on the charge state of the phone itself. If you start a heavy game, the phone starts to discharge then the discharging slows down (case power input increases) and stops at around 90%. This is quite a crappy situation I think. Especially when you lose another 20 % percent of case battery for charging up from those 90% of iPhone battery because charging the last 10% of battery from another is very inefficient. Why let the phone battery to discharge ? Why let the battery charge when it is full ? Here the illusion that the case is like another battery to the phone falls apart. It behaves more like a powerbank, that augments the output of internal battery.

This may relate to another flaw. While the charging behaviour is generally very good. The charging speed of the battery case does again depend on charge state of the iPhone. Even with a 12W charger the case charges very slow when the iPhone is fully charged, comparable to using a 5W charger. The rate of case charging increases as the phone discharges, until the phone takes more power for itself of course. Getting rid of the case and charge it solo can be much faster, but this isn’t lazysumer-friendly.
While I must admit that Apple pushed the battery case behaviour in good direction compared to competition, the flaws that remain still point to the fact that Apple does not take this product quite seriously. There was probably a problem with that the iPhone only knows a charger in hardware, and not a battery case. Those flaws might be because I used the oldest officially supported duo - iPhone 6 and iPhone 6S smart case - it is possible that newer pairs behave better. Do you have any experience with them ???

The future ?

While the battery case was deemed as unnecessary piece of bump, a year later Apple has unrelieved a smart case for iPhone 7. That is despite the fact that battery life improved significally for that generation, so much I was content with the phone battery itself (not a heavy user here).
What was interesting that Apple has upped the case capacity by over 20 percent, in pretty much identical form factor.
Then a year later, we got iPhone 8, 8 Plus and X which were another step battery wise, considering frugal 10nm chipset. The iPhone 8 was not even listed compatible with previous cases. The reason was simple right ? A battery would block the wireless charging coil, which by itself added weight and thickness to the phone.

Then there came iPhone XS, XS Max and XR all promising improved battery life. In case of the XR quite a stratospheric one. But suddenly not only a battery case was released, it was released for all three devices, including the XR, which definitely was not an attempt to bring it in line with a Plus model. All models costed more, lost their chin for uniform “bezelles” look, they implemented the same about 10 Wh battery, and wireless charging. It seems quite ridiculous for me to carry not one, but 2 big, heavy and inefficient charging coils, but there is no going around the fact that batteries are conductive by definition… and that some people will want to charge that 20 Wh cistern wirelessly. The controversy around the cases remained. In something that seemed as trolling to me, every single site I could find was like: “New battery case is more expansive, yet only has a tiny tiny 1300 mAh capacity, which can charge your iPhone to 45% !“. Well, nobody could read the internal label with capacity in Wh ? That probably means there are two cells inside. That is too much for today’s media (aside Anandtech of course) to grasp correctly. By the way does anybody know about some teardown of those newest cases ?

Considering Apple is aggressively targeting longer battery life since 2016, we could definitely expect another step in this direction on 10.9. The question is, will there be a new smart battery case ? If Apple takes this seriously, they will, or already tried to fix the issues mentioned higher. If not, it is just going to disappear at some point. While many people are fine with the battery life of their phone, there are still ones who just want more and more. Like me who just wanted to try out. I would like to thank you for reading, ask you for your own experience with battery cases in general and what do you think of this industry going forward.