iPhone Slow? An Old Battery Might Be To Blame


Your battery might be making your older iPhone slow. This is because, apparently, iOS system software sometimes slows down older iPhones when the internal battery has degraded to the point where it can no longer sufficiently power the device at the expected performance level.

According to Apple, the throttling of device speed is intended to prevent the iPhone from crashing or shutting down unexpectedly due to a worn batteries diminished capabilities.

Unfortunately, that device speed throttling could have an annoying side effect of making the older iPhone noticeably slower to the end user. This is often noted after new iOS system software releases, though it should be pointed out that sometimes any observed performance degradation irons itself out over time, or can be successfully resolved with various iOS troubleshooting steps and settings adjustments on the impacted device. But, sometimes an older iPhone or iPad just feels persistently slow, and that could very well be due to having an old degraded battery.

This battery and device speed issue has gained considerable attention lately, after a series of iPhone users discovered that system benchmarks were notably underperforming on older iPhone models. For example, a widely tweeted set of screenshots and report from Twitter user @sam_siruomu showed performance benchmarks where an iPhone 6 was under clocking itself down to 600mhz, but after replacing the battery with a new one the speed corrected back to the proper 1400mhz. That anecdotal twitter report has been captured in a screenshot below:

iPhone battery performance throttled by old battery and performance was restored with a new battery

The device benchmarking company Geekbench also seemed to confirm an occasionally observable underperformance of older iPhone models based on referencing their own benchmarking data.

With considerable hubbub generated online, and plenty of related rumors and conspiracies, Apple released a statement to TechCrunch and Buzzfeed that said the following:

“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.

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.”

That statement and admission from Apple is interesting, because there has long been speculation and conspiracy theory that Apple intentionally slows down older iPhone (and iPad) devices with iOS system software updates, but until now most users didn’t know why, they just anecdotally observed it on their devices. That notable performance degradation led to countless theories about why it might happen, along with other theories denying it happens at all and insisting it was imaginary. Well, it turns out that some observed performance decline may directly relate to the older devices battery age and quality.

How this all shakes out remains to be seen, as there are already lawsuits against Apple about the battery issue, and the topic has also reinvigorated Right-to-Repair advocates who argue that it’s consumer friendly to be able to easily and reasonably repair your own stuff.

This may all sound bad, but there’s actually good news here. If indeed an iPhone (or iPad) device slowdown is entirely due to an old battery, then replacing the battery should theoretically boost performance back to expectations, much as it did for the Twitter user we cited above, and that has been anecdotally reported as successful elsewhere around the web too.

Of course a notable difficulty here is that iPhone does not typically report that its internal battery is old enough to have degraded device performance, nor does the iPhone have an easily replaceable battery. The former situation is something that could be theoretically addressed in a future iOS software update, with a notification along the lines of “battery has degraded and can no longer support optimal device performance” or something similar, perhaps with a link to battery replacement options. The latter difficulty of not having an easily replaceable battery means you’d either need to get an old worn battery replaced by a competent repair center, or take it upon yourself as a DIY project.

If you do have an older iPhone (say an iPhone 6 or iPhone 6s) that feels unreasonably slow, and you want to see if a battery replacement will restore performance, you’ll need to either contact Apple or an Apple authorized repair center and pay $80 for a battery replacement, or you can get a Do-It-Yourself iPhone battery replacement kit on Amazon for around $40 or so. There’s no guarantee that replacing a battery is going to speed things up and make an older device as snappy as it used to be, but it just might boost performance for some devices under the right set of circumstances.


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