5 Signs Your iPhone Battery Needs Replacing (And What to Do About It)

Your iPhone is one of the most important tools you carry every day. But no matter which model you own — whether it’s an iPhone 14, iPhone 15 Pro, or the latest iPhone 16 — the battery will degrade over time. Apple designs iPhone batteries to retain up to 80% of their original capacity after 500 full charge cycles. After that, performance can drop noticeably.

The good news? A battery replacement is one of the most affordable and impactful repairs you can make. At Phone Heroes in Earl’s Court, we replace iPhone batteries in as little as 30 minutes — and your phone will feel like new again.

Here are five clear signs that your iPhone battery needs replacing.

1. Your iPhone Is Draining Much Faster Than It Used To

This is the most common complaint we hear at our Earl’s Court repair shop. If your iPhone used to last all day on a single charge but now needs a top-up by early afternoon, that’s a strong indicator that your battery health has declined.

To check your battery health, go to Settings > Battery > Battery Health & Charging. If the maximum capacity reading is below 80%, Apple itself recommends a replacement. Anything below 85% and you’re likely already noticing reduced performance.

A degraded battery won’t just drain faster — it can also cause your iPhone to run warmer than usual and trigger unexpected behaviours across apps.

2. Your iPhone Shuts Down Unexpectedly — Even With Battery Remaining

One of the most frustrating symptoms of a failing battery is your iPhone powering off suddenly — even when it shows 20%, 30%, or more battery remaining. This happens because an aged battery can no longer deliver the peak power that the iPhone’s processor demands under load.

When the battery can’t sustain the power draw, your iPhone shuts itself down as a protective measure. If this is happening to you regularly, a battery replacement is almost certainly the solution.

This issue tends to get worse in cold weather, when battery chemistry performs less efficiently — another sign the cells are past their best.

3. Your iPhone Is Slower Than It Used to Be

Apple introduced a feature called performance management, which automatically reduces your iPhone’s processor speed to prevent unexpected shutdowns caused by an ageing battery. While this protects the hardware, it means your phone may feel sluggish — apps take longer to open, animations stutter, and the camera is slower to respond.

Many people assume their iPhone is just getting old and start thinking about an upgrade. In many cases, a simple battery replacement is all that’s needed to restore full speed and responsiveness. At Phone Heroes, customers are often amazed at how much faster their phone feels after a battery swap.

You can check whether performance management is active on your device by going to Settings > Battery > Battery Health & Charging and looking for any performance management notices.

4. Your iPhone Gets Unusually Hot During Normal Use

It’s normal for your iPhone to get slightly warm during intensive tasks — gaming, video calls, or using GPS for long periods. But if your device regularly feels hot during everyday tasks like browsing, messaging, or streaming, the battery may be to blame.

An ageing lithium-ion battery has to work harder to deliver the same power output, generating more heat in the process. Excessive heat can also accelerate the degradation of other components over time — so it’s worth addressing sooner rather than later.

If your iPhone is running warm alongside any of the other symptoms on this list, a battery replacement should be your first step.

5. Your Battery Health Is Below 80% — Even If You Haven’t Noticed Symptoms Yet

Sometimes battery degradation is gradual enough that you adapt to it without realising. You start charging more frequently, you carry a portable power bank, or you just accept that your phone doesn’t last as long as it used to.

If you check your Battery Health and see a reading below 80%, we’d recommend replacing the battery even if you haven’t noticed dramatic symptoms yet. Proactive replacement means you won’t be caught short during a busy day — and it’s far cheaper than buying a new phone.

At Phone Heroes in Earl’s Court, iPhone battery replacements start from £39 and take around 30 minutes. We use high-quality replacement batteries and back every repair with a one-year warranty.

How to Get Your iPhone Battery Replaced at Phone Heroes

Getting your battery replaced couldn’t be simpler. Our repair shop is located at the Warwick Road Entrance of Earl’s Court Underground Station — right in the heart of West London, convenient for commuters, residents, and anyone passing through Kensington or Chelsea.

There’s no need to book an appointment. Walk in during opening hours, hand over your iPhone, and in around 30 minutes you’ll have a fresh battery — backed by our one-year warranty. We replace batteries on all iPhone models from iPhone 6 through the latest iPhone 17 series.

Not sure if your battery needs replacing? Walk in for a free battery health check. Our technicians will assess your phone at no charge and give you an honest recommendation. If a replacement isn’t needed, we’ll tell you.

Call us on 020 3397 7407 or visit phoneheroeslondon.co.uk to find out more.