Understanding The Curious Case of iPhone Batteries

While the accusations against Apple cannot be denied, there does seem to be some truth in Apple’s explanation.


Apple did not start 2018 with the positivity they would have wanted, even after the success of iPhone X. The reason — their deliberate throttling-down the performance of older iPhone models has not gone down well with users and critics alike. iPhone owners are upset and several have filed lawsuits alleging that Apple, by failing to disclose that it would throttle down their phones, has swindled them in a sneaky attempt to buy newer iPhones and some have even claimed monetary loss.

There existed speculations around the performance of the iPhone being throttled down with time, however most of us disregarded them as errant rumors and even sidelined the people who had incessantly insisted that they do, as we were not showed proof and were merely audience to the pelted allegations. One inquisitive user — one small measurement — one statement from Apple and the whole speculation turned on its head to become a dreaded reality. After the grins (I told you so), the sneers (I knew Apple was up-to something), the disbelief (I never thought Apple could do this) and a whole range of emotions having manifested, shared and consumed, let us bring semblance of what actually happened and why.

The entire conflict began with a Reddit user’s innocuous experiment around why his iPhone 6S had slowed down and why it perked up again after a battery replacement. Using the Geekbench app, he realized that the most recent iOS 11.2 update had slackened the performance of his iPhone, which disappeared upon replacing the battery. This led a team at Geekbench to further test this hypothesis and prove with data that the claim — Apple throttles down older iPhones is true. After a few days Apple confirmed the same and issued an apology for erroneously withholding this information from their users along with an explanation of why this was done. By then the damage had been done and the trust that Apple had erstwhile enjoyed had taken a beating, exposing Apple to the wrath of their loyal users amidst the rant of iOS naysayers.
 Let us explore the battery to understand its delicate relationship to the device hardware and performance.

Lithium-ion battery is a chosen means for powering your smartphone by OEMs as it is lighter, denser, lasts longer, and charges faster in comparison to the other market viable technologies available for batteries. However, these batteries do come with a “chemical age” driven by your usage (number of charge cycles, frequency of charge cycles) and maintenance, directly affecting the battery performance and lifespan. As these lithium-ion batteries age w.r.t. their chemical constitution, the amount of charge they hold diminishes, resulting in the users having to charge their device more frequently than before. Chemical ageing decreases the ability of an optimally functioning phone to spontaneously draw power from the battery. Another factor affecting the power delivery mechanism is the impedance of a battery, which increases as it ages chemically. Higher impedance equals more resistance and thus lower power delivery. There is a minimum voltage that the electronic components, like the battery, power circuits or internal storage of the device needs to operate and a battery with high impedance is unable to provide power quickly enough to the system that needs it. While sub-optimal temperature, harsh environment and a low charge state can increase the battery impedance for a short amount of time, a battery with a higher chemical age in the same conditions would substantially dither in its voltage delivery.

Modern devices have a power management system responsible for managing delivery and utilization of power to maintain optimal operation. When this power management system feels the conditions are not conducive for operation, it shuts down the device to safeguard the electronic circuitry and components against damage. This shutdown is seen as erroneous and spontaneous by the user when in fact, it is completely intentional and systematic. As the battery gets older, it becomes inefficient with it’s power retention and power delivery allowing for device shutdowns, thereby making the device unreliable. In order to keep up with the ageing battery, the device performance needs to be throttled down to keep pace with the diminishing power management so that the device does not have unexpected shutdowns.

The power management feature takes into account battery impedance, its charge state and the device temperature before managing the performance limit for the device CPU and GPU, thereby allowing for an even distribution of the device workload instead of spontaneous quick bursts of power sapping workload, thus avoiding damage or sudden shutdowns. In terms of how this affects the device in practical usage — it may lead to lower speaker volume out (by up to -3dB), backlight dimming (lowering screen power utilization), lower frame rates while scrolling, longer app launch times, etc. If there are any apps that are refreshing in the background, they will need to be reloaded when you launch them and in extreme cases, the camera flash will be disabled. However, this feature will not effect device sensors, captured audio and video quality, call quality and networking throughput and the GPS performance for location precision along with Apple Pay. These changes are temporary if the battery is in a low charge state or if the device is in operation in sub-optimal temperatures, however these changes could be permanent if the battery has aged chemically and a replacement battery would then be a viable solution to get the device back to its original performance.

In their statement, Apple said that for their older devices, the iOS 10.2.1 update came with a feature to prevent these shutdowns. iPhone 6, iPhone 6 Plus, iPhone 6s, iPhone 6s Plus, and iPhone SE had received this feature to dynamically manage the sudden performance peaks and stop the device from promptly shutting down. iOS 11.2 extended this feature to iPhone 7 and iPhone 7 Plus models as well. On their page for “iPhone Battery and Performance”, the team at Apple have shared that changing to a new battery could improve the phone performance — “For a low battery state of charge and colder temperatures, power management changes are temporary. If a device battery has chemically aged far enough, power management changes may be more lasting. This is because all rechargeable batteries are consumables and have a limited lifespan, eventually needing to be serviced or recycled. If you are impacted by this and would like to improve your device performance, replacing your device battery can help”.

Apart from offering an explanation around the workings and eroding of lithium-ion batteries powering their devices, Apple has also apologized and followed it up with a remedial action: “We know that some of you feel Apple has let you down. We apologize… we have never — and would never — do anything to intentionally shorten the life of any Apple product, or degrade the user experience to drive customer upgrades. Our goal has always been to create products that our customers love, and making iPhones last as long as possible is an important part of that.” As damage containment, Apple has reduced the battery replacement cost of an out-of-warranty iPhone from $79 to $29 for iPhone 6 or later models. In India, this cost has gone down from INR 6,000 to INR 2,000 plus taxes and should be available through 2018. In addition, the company will be releasing an iOS software update in early 2018 with a feature that will give users better feedback on their iPhone’s battery health.

Geekbench is a paid app that does comprehensive testing of your device’s performance. It has become a standard today for testing smartphone performance in areas such as CPU, GPU, speech recognition, camera, rendering capabilities, etc. For the many of you who might not want to pay for an app, there are free apps like Performance Benchmark and Battery Life to gauge your battery health. These apps won’t test your device like Geekbench 4, but still give battery’s raw data, runtimes, and health status for you to gauge your battery health.

The damage was done due to a lack of proactive communication by Apple. The company had been receiving customer feedback for slow performance of iPhones for months before the whole thing was put out in the open. Consumers consciously pay a higher price to purchase iPhones for the user experience it offers, and to find out that they have been throttling down your device performance while keeping you in the dark constitutes an offensive breach of the trust that the buyers place in Apple. If Apple had addressed their user concerns on diminishing device performance, they could have avoided this scandalous bump in their legacy with their user loyalty and brand image not having to loose lost traction in the market.

Now on their proposed remedial solution — Apple should not be charging for replacement batteries at all considering the cost of the iPhone itself, especially in developing nations. Consumers are willing to pay for the user experience and the durability that Apple products bring. Tarun Pathak, associate director at Counterpoint Research, rightly contends that “A two-year-old iPhone such as the iPhone 6s still costs around INR 37,000 and paying INR 2,000 to get its battery replaced within a year of purchase is asking for a lot, especially in developing markets like India. Ideally, Apple should not have charged for replacement batteries for the affected phones. A large chunk of iPhone buyers in India go for iPhones that are a generation or two older. In such cases, it becomes critical for Apple to be upfront about issues pertaining to older iPhones.” Consumers should know about maintenance costs like that before making the purchase.
 Could this mess have been avoided if Apple had simply been upfront with its customers from the beginning?

Users feel that the iOS update around their battery performance status could have been rolled out earlier giving the user choice to continue running the device for performance and risk unexpected shutdowns or consciously throttle it down to keep it functioning modestly. By taking matters into its own hands, the users feel that Apple has kept them in the dark and customers are not taking this lack of choice and breach of transparency lightly.

While the accusation against Apple cannot be denied, there does seem to be some truth in Apple’s explanation. Apple, on its website, mentions that “All rechargeable batteries are consumables and have a limited lifespan — eventually their capacity and performance decline so that they need to be serviced or recycled. As this happens, it can contribute to changes in iPhone performance.”

Too little too late!


Originally published at Chip-Monks.