How to Change an iPhone Battery: A Practical Guide

Is your iPhone constantly dying on you? Or maybe it feels permanently attached to a charger cable? It’s a familiar story we hear all the time with older iPhones, and even some used ones. This guide will walk you through your options, from checking if the battery is the real problem to deciding whether a DIY replacement, a professional repair, or upgrading to a newer refurbished mobile makes the most sense for you.

You've really got three main options: doing it yourself (DIY), getting it done by a professional, or deciding if it’s time to upgrade. A quick check of your battery's health in the settings is the best place to start. If it's below 80% maximum capacity, a replacement will almost certainly give your mobile a new lease of life.

Your iPhone Battery Options at a Glance

Option	Best For	Average Cost (UK)	Key Consideration
DIY Replacement	Tech-savvy users on a tight budget who are comfortable with delicate electronics.	£20–£40	High risk of damaging your phone if you make a mistake. Requires special tools.
Professional Repair	Anyone who wants a guaranteed, hassle-free fix without risking their device.	£60–£100+	More expensive than DIY, but includes expert labour and often a warranty.
Upgrade to Refurbished	When your phone is old and a new battery is only a temporary fix for other issues.	Varies by model	A smart long-term investment if your current phone is slow or nearing the end of its software support.

Deciding between these really comes down to your budget, your technical confidence, and the overall condition of your current iPhone.

Should You Change Your iPhone Battery?

Before you start ordering parts or booking repairs, the first thing to do is make sure the battery is actually the problem. Thankfully, your iPhone has a handy built-in tool that gives you a clear picture of its health. It’s the perfect starting point.

How to Check Your Battery Health

Finding this feature is simple, though the exact path can vary slightly depending on your iOS version.

• For most recent iOS versions: Head to Settings > Battery > Battery Health & Charging.
• For older iOS versions (like iOS 16.0 and earlier): Go to Settings > Battery > Battery Health.

In this menu, you’ll see the most important number: 'Maximum Capacity'. This percentage tells you how much charge your battery can hold compared to when it was brand new. A fresh-out-the-box iPhone should be at 100%. This number naturally drops over time with every charge cycle.

Understanding Maximum Capacity

So, what’s a "good" number? From our experience, once a battery's capacity dips below 80%, the performance problems really start to become noticeable.

We recently helped a customer with a used iPhone 11 whose battery would plummet from 40% to 10% in just a few minutes. We took one look at the settings and saw its maximum capacity was down to 74%. This is a classic sign that the battery’s chemistry has degraded and it can no longer deliver stable power.

Apple agrees. They officially consider a battery worn out when it falls below that 80% threshold. In fact, if your battery is significantly degraded, iOS will often show a message right there in the settings, recommending a service. This isn't a safety warning, but it’s a clear signal that the battery is holding your phone back. You can find more detail in our complete guide to refurbished iPhone battery health.

Other tell-tale signs of a failing battery are pretty easy to spot. Watch out for your iPhone suddenly shutting down even when it shows plenty of charge, or if it gets unusually hot during normal use. For more on these symptoms, you can explore this helpful guide on iPhone battery health. If you’re seeing these signs and your capacity is low, a new battery is almost certainly the solution.

Preparing for a DIY iPhone Battery Replacement

Taking on a DIY battery replacement can feel very rewarding, but proper preparation is everything. I’ve seen it countless times: people rush in without the right setup and turn a simple job into a costly mistake.

Let’s get you prepped so that doesn't happen.

Back Up Your iPhone First

WARNING: There is a risk of data loss if something goes wrong during a DIY repair. Before you even think about touching a screwdriver, you absolutely must back up your phone. This isn’t an optional step. If a tool slips or a tiny cable tears, this backup is your only safety net for all your photos, contacts, and messages.

It’s easy to do. Just head to:

Settings > [Your Name] > iCloud > iCloud Backup

Check that ‘iCloud Backup’ is toggled on, then tap Back Up Now. Give it time to complete fully. Trust me, this simple action could save you a world of heartache later.

Get the Right Tools and Parts

You can’t do this job properly with the random screwdrivers from your kitchen drawer. iPhones use tiny, specialised screws that are incredibly easy to strip or damage. You’ll need a dedicated iPhone repair kit.

A good kit should always include:

• Pentalobe Screwdriver (P2): For the two screws on the bottom edge of your iPhone, right by the charging port.
• Tri-Point Screwdriver (Y000): Essential for the internal screws over the connector plates on the iPhone 7 and newer.
• Small Phillips Screwdriver: Used for various other internal screws.
• Plastic Prying Tools (Spudgers): Crucial for safely disconnecting delicate ribbon cables without causing any damage.
• Suction Cup: Helps you lift the screen away from the phone’s body.
• Tweezers: For handling all those fiddly little screws and components.
• Battery Adhesive Strips: Don’t skip these. You need fresh adhesive to secure the new battery properly.

Finding a quality replacement battery is just as important. We strongly advise you to steer clear of the cheapest, uncertified batteries you find online. They’re a false economy, plain and simple.

A customer brought in a refurbished iPhone 12 Pro just last month that wouldn't hold a charge, even though they’d just replaced the battery themselves. They'd grabbed a cheap one online for under a tenner. When we opened it up, the battery wasn't even the right fit and was missing the correct temperature sensors—a massive safety risk.

A poor-quality battery can cause overheating, awful performance, and a much shorter lifespan. Always look for batteries from reputable suppliers that offer a warranty and clearly state they use high-quality cells. It’s well worth spending a bit more for peace of mind. For a deeper look at the risks, you might want to read our guide on whether you can repair a second-hand iPhone yourself.

Set Up Your Workspace

Finally, get your workspace ready. You need a clean, well-lit, and organised area. A cluttered desk with dim lighting is a recipe for losing screws and making mistakes.

Take a look at how compact and intricate the inside of an iPhone is.

The tiny screws and connectors are packed in tight, which is exactly why a tidy workspace is so critical.

I recommend using a magnetic mat or even just a few small containers to keep track of every screw as you remove it. The screws inside an iPhone have different lengths, and putting one back in the wrong hole can permanently fry the logic board. Taking your time to prepare properly is the single best thing you can do to ensure a successful repair.

The iPhone Battery Replacement Process Explained

Right, this is where we get our hands dirty. We're going to walk through the battery replacement with the care and precision of a seasoned repair technician. While the exact steps might differ slightly between models—an iPhone 8 opens differently to an iPhone 13—the core process is pretty similar across most recent iPhones.

Remember, patience is your best friend here. This isn't a race. A methodical, unhurried approach is the key to minimising risk and avoiding a simple repair turning into a costly mistake.

A Step-by-Step Walkthrough

Before you even think about picking up a screwdriver, power down your mobile completely. Don't just lock the screen; hold the side button and a volume button until the "slide to power off" slider appears, then switch it off. It's also a smart move to let the battery run down below 25% charge. A fully charged battery is more volatile if you accidentally puncture it.

Opening the iPhone

First things first, you need to remove the two tiny pentalobe screws on either side of the charging port. These hold the screen assembly to the frame, so use the correct P2 pentalobe screwdriver and keep these screws somewhere safe and organised.

Next, you need to deal with the adhesive. iPhones are sealed with a strong waterproof glue around the edge of the screen. To make opening it easier, you'll have to gently heat this adhesive. A heat gun on a low setting or even a hairdryer will do the job. Move it around the edges of the screen for about a minute until the glass is warm to the touch, but not hot.

Now for the delicate part. Place a suction cup on the screen, just above where the home button would be (or near the bottom edge on newer models). Pull up gently but firmly on the cup to create a small gap between the screen and the frame. You’re not trying to rip it open, just create enough space to slide a thin plastic prying tool inside. Once you have a gap, work the tool around the edges to separate the screen from the body.

Technician's Tip: One of the most common mistakes we see is people rushing this step and tearing the delicate display or Face ID cables. These ribbon cables are incredibly fragile. Open the screen slowly, like you’re opening a book, and pay close attention to which side the cables are on. On most models, they are on the right, so you’ll want to open the screen from left to right.

Disconnecting the Old Battery

Once the phone is open, the very next thing you must do is disconnect the old battery. This is a critical safety step to prevent any short circuits.

• Find the Connectors: You’ll see several connectors hidden under a small metal plate held down by tiny screws. This is where your tri-point and Phillips screwdrivers come in. Carefully remove the screws for the plate covering the battery and display connectors.
• Disconnect in Order: Always use a plastic prying tool—never metal!—to gently pop off the battery connector first. After that, you can disconnect the display connectors.
• Remove the Old Battery: The battery itself is held in by several stretchy adhesive tabs. The trick here is to pull these tabs out slowly and at a very low angle, almost parallel to the battery. If you pull too hard or at a high angle, they’ll snap, making removal a real pain. If a tab does snap, you might need to use a plastic tool and a bit of isopropyl alcohol to carefully pry the battery out. Be extremely careful not to bend or puncture the battery.

Installing the New Battery

With the old battery out, you're on the home stretch. Reassembly is basically the reverse of what you've just done, but it requires the same level of care.

Securing and Reconnecting

First, apply the new adhesive strips to the back of your new battery in the correct positions. Don't skip this; these strips stop the battery from rattling around inside the phone, which could damage other components.

Next, carefully place the new battery into the chassis. This time, reconnect the display connectors first, and then reconnect the battery connector. This reverse order is important. Once they're connected, pop the metal shield and its screws back in place.

Before you seal everything up, it’s a good idea to power the phone on to test that the new battery is recognised and the screen is working properly. If it all looks good, power it down again.

Finally, carefully align the top edge of the screen into the frame and then gently press down around the edges until it clicks securely into place. Replace the two pentalobe screws at the bottom, and you’re done. While a new set of water-resistant seals should be applied, getting a factory-level seal at home is nearly impossible, so it's best to be extra cautious around liquids from now on.

Replacing an iPhone battery is a delicate operation, but it's completely achievable with the right preparation and a steady hand. The satisfaction you'll get from bringing an old mobile back to life is well worth the effort.

Professional Repair vs Buying Refurbished

So, you’ve decided a DIY repair isn’t for you. That’s completely fine. If the thought of prying open your expensive iPhone gives you cold sweats, you’re left with two solid choices: get it professionally repaired or upgrade to a newer refurbished model. Let’s weigh them up properly.

Opting for a Professional Repair

When you need professional help, you can either head to an Apple Authorised Service Provider or a trusted independent repair shop. Apple’s own service guarantees an original battery and keeps your warranty intact, but it’s almost always the priciest route. A good independent shop, on the other hand, can be much more affordable and just as reliable, as long as they have a strong reputation and use high-quality parts.

If you’ve ruled out doing it yourself, seeking out professional Apple repair services is a great way to make sure the job is done safely and correctly. Just be sure to ask about their warranty on the repair and what kind of battery they’ll be fitting. Any reputable shop will be happy to tell you.

Knowing When an Upgrade Makes More Sense

Repairing is a smart move for a relatively new phone, but what if your iPhone is getting a bit long in the tooth? This is where you need to start thinking about long-term value.

We see this scenario play out all the time. Someone might have an older iPhone X, and a professional battery swap costs around £85. It sounds like a reasonable fix, but that phone is now several years old, will soon stop getting major iOS updates, and probably feels a bit sluggish compared to modern devices.

For not much more than the cost of that single repair, you could upgrade to a certified refurbished iPhone 12. This gets you a fresh battery, a much faster processor, better cameras, 5G connectivity, and—crucially—a full 12-month warranty for complete peace of mind.

This is the tipping point where simply replacing the battery stops being a good investment. You’re just putting money into a device that’s already nearing the end of its useful life.

The Real Cost of Fixing an Old Phone

Thinking about the long-term benefits is key. It's not just that newer iPhones have better features; their batteries are also engineered to last longer. Apple's own data shows that iPhone 14 models and earlier are designed to retain about 80% of their capacity after 500 charge cycles. In contrast, the iPhone 15 models are built to last for 1,000 cycles before hitting that same 80% mark. You can read more on Apple's battery cycle findings on their official site.

This means a newer model gives you significantly better longevity right out of the box.

Let’s break down the real-world trade-offs with a simple comparison, using our iPhone X example.

Cost and Benefit Analysis: Repair vs Refurbished (Example iPhone X)

Here's a look at how the numbers and benefits stack up when you compare fixing an old device versus upgrading.

Factor	Professional Battery Repair	Buying a Refurbished iPhone 12
Initial Cost	Around £85	From approx. £220-£250
Warranty	Typically 3–12 months on the battery only	Full 12-month warranty on the entire device
Performance	No change to the ageing processor	Significant speed and feature upgrade (A14 chip)
Software Support	Limited; will lose iOS updates soon	Several more years of guaranteed iOS updates
Future Costs	Other components might fail soon after	All components tested and certified, reducing risk

When you lay it all out like this, the choice becomes much clearer. Pouring money into an ageing phone often feels like a temporary patch. Upgrading to one of our quality refurbished iPhones provides a far better long-term solution, giving you a more capable and reliable device that will serve you well for years to come.

Why iPhone Battery Replacement Became So Common

It might seem like a niche job, but knowing how to change an iPhone battery has become common knowledge for a very good reason. For years, a slowing iPhone usually meant one thing: it was time to shell out for a brand-new, expensive mobile. But a major shift back in 2018 completely changed how people thought about their devices.

The Turning Point in 2018

Cast your mind back to 2018. Apple found itself in hot water after it was revealed they were deliberately slowing down older iPhones. Their intention was to prevent unexpected shutdowns as batteries aged, but the news didn't go down well. In response, they launched a heavily discounted battery replacement programme, and the effect was massive.

The demand was staggering. Apple ended up replacing around 11 million batteries that year—a figure nearly 11 times higher than their usual annual rate. This all happened as the new iPhone XR and XS were hitting the shelves, yet millions of users chose a simple battery swap over a pricey upgrade. You can read more about this surge in battery replacements to get a sense of the sheer scale.

That one event taught UK customers a powerful lesson: more often than not, it was the battery, not the entire phone, that was the real problem.

A New Mindset for Phone Owners

This change in thinking is especially important if you're buying or own a used or refurbished phone. It’s proof that extending a device's life is a smart, practical, and sustainable choice. A new battery can breathe new life into an older iPhone, restoring its performance for a fraction of the cost of a new handset.

We frequently get customers asking if it's worth putting a new battery in their old iPhone 11 or SE. They’re often surprised when we explain that for many users, a fresh battery is all it takes to make the phone feel fast and reliable again for another couple of years.

Understanding this history helps you see a battery replacement not just as a repair, but as a savvy investment. It allows you to get more value from the mobile you already own or gives you the confidence to buy a refurbished model, knowing that its lifespan can be easily and affordably extended. It’s a core principle behind the value of the refurbished market today.

Common Questions About iPhone Battery Replacement

Over the years at the repair counter, you hear the same questions about iPhone batteries pop up again and again. Whether you're weighing up a DIY attempt or leaning towards a professional service, it's completely normal to have a few things you're unsure about. To give you a bit more confidence, here are some straight-talking answers to the queries we hear most often.

How Long Does a Replacement Take?

This is easily the number one question we get asked. A professional repair is surprisingly fast. For an experienced technician who has all the right tools to hand, a standard iPhone battery swap usually takes between 30 to 60 minutes.

If you're going down the DIY route for the first time, you absolutely need to give yourself a bigger window. We always suggest setting aside at least 90 minutes to two hours. Rushing is the fastest way to cause damage, like tearing a delicate ribbon cable or losing a minuscule screw. Patience is your best friend here.

Will a New Battery Make My Old iPhone Faster?

Yes, in many situations, it absolutely will. This isn't just a placebo effect; there’s a solid technical reason for it. As your iPhone's battery gets older, its ability to deliver peak power drops. To stop your phone from unexpectedly shutting down, Apple's iOS includes a feature known as performance management, which intentionally throttles the processor.

When you pop in a fresh battery with 100% health, that performance management feature is disabled. The processor can draw its full power again, which often brings back the phone’s original speed and snappy responsiveness. It’s amazing how many people are genuinely shocked by how much quicker their iPhone feels afterwards.

Is a DIY Replacement Safe?

It can be, but you have to go into it aware of the risks. Lithium-ion batteries are no joke. They can be hazardous if you accidentally puncture, bend, or damage them during removal, which could lead to a fire or a dangerous chemical reaction.

If you’re methodical, follow instructions to the letter, use the proper tools, and work slowly in a well-organised space, you can keep the risks to a minimum. That said, if you're not comfortable handling fragile electronics and potentially hazardous materials, a professional repair is always the safer, more sensible choice.

Does Changing the Battery Affect Water Resistance?

Yes, it does, and this is a critical point that’s often overlooked. When an iPhone is opened up for any repair, the factory-applied water-resistant seals running along the edge of the screen are broken.

While a good repair shop will replace these adhesive seals, your device will almost certainly not have the same level of water resistance it had straight out of the box. We always tell customers to be extra careful around water after any kind of repair, even one done by a pro. It’s far better to assume it’s no longer water-resistant. You can read more in our other guide about how a battery replacement history can be spotted.

Battery longevity is a hot topic, and a common worry is whether leaving your phone plugged in overnight is bad for it. Modern iPhones have clever safeguards, but it’s still useful to understand the facts. For anyone curious, there's a lot of great info on whether does charging your phone overnight is myth or reality.

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If your old phone is starting to feel like more trouble than it's worth, upgrading might just be the simplest fix. At Used Mobiles 4 U, we have a huge range of certified refurbished iPhones that come with a fresh battery and a full 12-month warranty. You can browse our collection at https://usedmobiles4u.co.uk.

Written by James Waterston — 24 years in the mobile phone industry from customer service through to Sales Director of a global repair and recycling company. Now running Used Mobiles 4 U for over 8 years.

LinkedIn:
https://uk.linkedin.com/in/james-waterston-9039a21a