{"id":19923,"date":"2017-12-22T15:25:53","date_gmt":"2017-12-22T20:25:53","guid":{"rendered":"https:\/\/mjtsai.com\/blog\/?p=19923"},"modified":"2022-05-27T17:01:09","modified_gmt":"2022-05-27T21:01:09","slug":"apple-confirms-that-it-throttles-iphones-with-degraded-batteries","status":"publish","type":"post","link":"https:\/\/mjtsai.com\/blog\/2017\/12\/22\/apple-confirms-that-it-throttles-iphones-with-degraded-batteries\/","title":{"rendered":"Apple Confirms That It Throttles iPhones With Degraded Batteries"},"content":{"rendered":"

Matthew Panzarino<\/a> (Hacker<\/a> News<\/a>):<\/p>\n

Here’s a statement that Apple provided when I inquired about the power profile that people were seeing when testing iPhones with older batteries:<\/p>\n

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Our goal is to deliver the best experience for customers, which includes overall performance and prolonging the life of their devices. Lithium-ion batteries become less capable of supplying peak current demands when in cold conditions, have a low battery charge or as they age over time, which can result in the device unexpectedly shutting down to protect its electronic components.<\/p>\n

Last year we released a feature for iPhone 6, iPhone 6s and iPhone SE to smooth out the instantaneous peaks only when needed to prevent the device from unexpectedly shutting down during these conditions. We’ve now extended that feature to iPhone 7 with iOS 11.2, and plan to add support for other products in the future.<\/p>\n<\/blockquote>\n<\/blockquote>\n\n

John Gruber<\/a>:<\/p>\n

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Prior to adding this feature to iOS last year, iPhones with older declining batteries were shutting down unexpectedly when taxed at peak performance. That’s obviously not good. So now, iPhones with older declining batteries are throttled, when necessary, to keep them running. But now Apple faces accusations that they’re deliberately slowing these devices down to convince people to buy new iPhones.<\/p>\n<\/blockquote>\n\n

Jason Koebler<\/a>:<\/p>\n

iFixit teardown engineer Jeff Suovanen performed similar tests with iFixit employees’ phones and shared the data with Motherboard.<\/p>

Suovanen found that iPhone 6S devices that still had their original batteries (they are about two years old now) had benchmark scores that were up to 57 percent lower than the GeekBench average. Replacing the battery instantly improved the benchmark scores drastically; he saw 70 percent swings in benchmark performance after swapping the old battery for a new one.<\/p>

“Everyone came back a day later and said, ‘Wow, it works so much faster,’” Suovanen told me on a phone call.<\/p>

[…]<\/p>

What makes it worse is that Apple does not make it easy to replace the battery yourself, discourages third party repair<\/a>, and doesn’t have the first party repair infrastructure to handle large numbers of in-store battery swaps, especially in states that don’t have lots of Apple Stores.<\/p><\/blockquote>\n\n

Andrei Frumusanu<\/a>:<\/p>\n

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Capacity and supply voltage of a battery decreases over time as a function of charge cycles and charging behaviour (Higher charging currents causing more degradation per cycle). This causes the total useable battery capacity before the cut-off voltage to decrease.<\/p>\n

The problem facing the iPhones as Apple explains it is however two-fold; the issue at hand happens only during load spikes in which the battery isn’t able to maintain a high enough voltage for the PMIC to reliably be able to use as a source.<\/p>\n

SoC blocks such as CPUs and GPUs can have very short transitions from idle to load causing steep transients and load spikes going above the +10W ranges. As batteries degrade over time and the cell impedance also rises also in function of the state of charge and temperature, the current flow becomes restricted and the cell is no longer able to satisfy the power requirement at a high enough operating voltage.<\/p>\n

[…]<\/p>\n

If this is the case then another question rises is if this is indeed just a transient load issue why the power delivery system was not designed sufficiently robust enough to cope with such loads at more advanced levels of battery wear? While cold temperature and advanced battery wear are understandable conditions under which a device might not be able to sustain its normal operating conditions, the state of charge of a battery under otherwise normal conditions should be taken into account during the design of a device (Battery, SoC, PMIC, decoupling capacitors) and its operating tolerances.<\/p>\n

If the assumptions above hold true then logically the issue would also be more prevalent in the smaller iPhone as opposed to the iPhone Plus models as the latter’s larger battery capacity would allow for greater discharge rates at a given stable voltage. This explanation might also be one of many factors as to why flagship Android and other devices don’t seem to exhibit this issue, as they come with much larger battery cells.<\/p>\n<\/blockquote>\n\n

Jacob Kastrenakes<\/a> (Hacker News<\/a>):<\/p>\n

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There is some good reason for Apple to do this. By their nature, lithium-ion batteries degrade over time, storing less and less of a charge. This happens very quickly on a device we use 24\/7. So it's not a bad idea for Apple to limit speeds on older phones, such that they don't push things too far on a depleted battery. That absolutely makes the phone more useable — it apparently helps stop random shutdowns, which are a major pain. And I would think it helps with battery life in general as well.<\/p>\n

But it also speaks to a really enormous problem with the iPhone: this $700 to $1,000-plus product, as designed, isn't able to function near its peak after just a year of use. That should be unacceptable.<\/p>\n

Slowing down the phone is one way to work against aging issues, but there are other, more obvious things Apple could do here. It could put larger batteries in the iPhone in the first place, so that they last longer before this kind of adjustment needs to kick in.<\/p>\n<\/blockquote>\n\n

Some of my thoughts:<\/p>\n\n