When to Replace iPhone Battery: 5 Warning Signs You Shouldn't Ignore

Batteries don’t last forever — and iPhones are no exception. If your device isn’t holding charge like it used to, you might be wondering when to replace iPhone battery components for good.

Here are five clear signs it might be time — plus advice on what to do next.

1. Your Battery Dies Before the Day Ends

Even with light use, your iPhone shouldn’t be on life support by mid-afternoon. If you find yourself constantly reaching for the charger, it’s a major red flag.

Some users try to manage this by turning on Low Power Mode or dimming the screen — but if you’re still running out of juice, it’s likely time for a replacement.

2. Your iPhone Shuts Down Unexpectedly

If your phone is randomly switching off at 20% or even 40%, it’s a classic sign of battery degradation.

This is especially common in older models — but we see it in newer iPhones too, especially in colder weather.

3. It Feels Slower Than It Used To

Apple has confirmed that iOS can slow down performance on phones with ageing batteries to avoid crashes. So if your apps are sluggish, animations stutter, or everything just feels “off” — it could be your battery, not your phone.

4. Your Battery Health Is Under 80%

You can check your battery’s health in Settings > Battery > Battery Health & Charging. If it says “Service” or the maximum capacity is below 80%, that’s your cue.

Some batteries last longer than others, but once it hits 79% or lower, performance and reliability will continue to decline.

5. Your iPhone Gets Hot — Even When Not in Use

Overheating is another sign your battery may be failing. If your phone is warm when idle or during simple tasks, the battery could be working overtime just to keep things running.

Bonus Tip: Don’t Wait Too Long

Waiting too long to replace a degraded battery can increase the risk of swelling or damage to internal components — and in rare cases, it can even crack your screen from the inside.

How Much Does iPhone Battery Replacement Cost?

At Kent iPhone Repair, we replace batteries from around £50, depending on your model. All work is done on-site — at your home, office, or local café — in under 30 minutes.

Check out our full battery replacement service or get in touch here.

We cover the whole of Kent, including:

• Ashford

• Maidstone

• Canterbury

• Whitstable

And everywhere in between.

If you’re not sure whether your battery needs replacing, just ask. We’ll give you an honest answer — and if your battery’s fine, there’s no charge.

No fix, no fee. Apple-quality parts. Friendly, mobile service.