If it feels like your old iPhone is slowing down, it may well be because Apple is slowing it down deliberately, to compensate for the aging battery. One solution is to buy a new phone, but there's a cheaper option: You can just replace the battery.

You can do this easily by bringing the phone to an Apple store.

Apple typically charges $79 to replace a phone battery. However, the company announced Thursday that it will drop the price to $29 for anyone with an iPhone 6 or later.

The new pricing is to take effect in late January and run through the end of 2018.

Why would slowing the phone's processor help with a dying battery? According to Apple, processor-intensive activities can cause a sudden increase in power demand.

The same thing can happen during normal operations when a phone has a very low charge, or is exposed to cold temperatures.

Apple said in a statement that the slowdown, which was rolled out for the iPhone 6, 6s, and SE last year, was intended to improve "power management during peak workloads to avoid unexpected shutdowns" in those models.

This fall, it extended this functionality to the iPhone 7 with the introduction of iOS 11.2, and the company said it will expand to other products in the future.

Slowing down the performance of phones with aging batteries might sound like a reasonable strategy in these circumstances. However, when Apple recently admitted to the practice, angry comments appeared across the internet and some consumers filed lawsuits.

In the message Thursday, the company acknowledged that many iPhone owners were angry about decreased performance. The company apologized, and said it was cutting the price of battery replacements "to address our customers’ concerns, to recognize their loyalty and to regain the trust of anyone who may have doubted Apple’s intentions." 

Apple also said that an iOS update in early 2018 would give consumers more information on the health of iPhone batteries "so they can see for themselves if its condition is affecting performance."

The bottom line: If you have an older iPhone that’s otherwise in good shape, you may be able to eliminate slowdowns by replacing your battery.

Here’s what you need to know, starting with how smartphone batteries age.

How Do Batteries Age?

As Indiana Jones said, “it’s not the years, it’s the mileage.” It really doesn’t matter how old your battery is, but how often you charge it.

Lithium-ion batteries degrade over time depending on how many charging cycles they go through. A heavy user who charges their phone midway through the day, then plugs it in again at night, will see their battery wear out significantly faster than someone who can go a couple days without adding juice, says Richard Fisco, Consumer Reports’ head of smartphone testing.

As a result, the effective life of a battery can vary greatly, he says.

David Reiff, co-founder and vice president of uBreakiFix, a chain of electronics repair stores, says that battery life expectancy for some phones can be as low as 300 to 500 charging cycles, which means that some users may not make it through a year before their battery performance starts to drop.

Meanwhile, the rest of the phone could, in theory, last forever if you don’t break it, since there are no moving parts to wear out, Fisco says.

But few people keep their phones long enough to test that theory, because even if a phone works well it eventually becomes outdated.

“The reality is, the operating system and therefore the apps available for it change,” Fisco says, adding that older phones will stop getting operating system updates from the manufacturer, which could prevent you from using newer apps.

And manufacturers eventually stop supporting old phones altogether, which means no security updates, putting hold-out users at risk for a hack, he adds.

So, Is It Worth Replacing My Battery?

That depends, Fisco says.

“If you’re a heavy user and you wear out your battery in a year, or less, then get the battery replaced,” he says. But he thinks it might not be worth the effort to replace the battery on older phones. 

First, check to see if your phone is still under warranty. In the case of iPhones, Apple’s warranty covers you against manufacturer defects for a year. If the battery is experiencing significant problems in that time frame, the company may be willing to replace it.

And, if you shelled out for AppleCare+ when you bought your iPhone, Apple will replace the battery for free for two years if they find that it retains less than 80 percent of its capacity.

And, of course, once the $29 pricing kicks in, many consumers may find it worthwhile to just see whether replacing the battery improves their performance.

Often this can be done quickly with a visit to an Apple Store, but Apple warns that in some cases it could take several days.

Companies such as uBreakiFix, which operates more than 300 stores in the U.S., Canada and the Caribbean, can do the replacement, too. Prices vary depending on the device—but you're not likely to find a better deal than what Apple is offering.

Can I DIY It?

In theory. But you won't save money by replacing an iPhone battery on your own—unless you have an older model that's not covered under Apple's new pricing.

If you do have an older iPhone, Amazon and other retailers sell kits that include a new battery and all the tools you’ll need. Replacement kits for an iPhone 5s battery sell for around $25 online.

But, this isn’t something that everyone will want to tackle. If you mess up, you risk bricking your phone. And, with more recent, water-resistant, phones breaking the seal yourself will make them susceptible to water damage.

Reiff from uBreakiFix also points out that doing this yourself will often void your warranty, though in most cases DIYers are repairing older phones where the warranties have already expired.

CR's Fisco urges caution. “If you are technically inclined, comfortable with small tools and devices and willing to risk breaking your phone then yes, you can DIY the battery replacement,” he says.

“Otherwise, get three price quotes from different repair shops and let them replace the battery.” 

 

Editor's Note: This article has been updated with new information about pricing for Apple battery replacements.