Why battery health matters when buying refurbished
Battery health is the single most important technical specification to check on any refurbished iPhone. It is the one component that cannot be tested simply by looking at the device, and it has a direct and significant impact on how the phone performs in everyday use.
An iPhone with 80% battery health holds 80% of its original charge capacity. A phone that lasted 12 hours of typical use when new will now last approximately 9–10 hours. At 70%, that drops to 8–9 hours. At 60%, you are looking at charging your phone twice a day. This is the difference between a phone that fits into your life and one that frustrates you.
What the battery health percentage actually means
When Apple displays battery health as a percentage, it is showing the ratio of current maximum capacity to the original designed capacity. A new iPhone has 100% battery health. This degrades with every charge cycle — the rate depends on how the battery is charged and used.
100–90%: Essentially like new. Either a barely-used device or one where the battery has been replaced.
90–85%: Good. Noticeable reduction in screen-on time compared to new but still comfortable for a full day of typical use.
85–80%: Acceptable. Most reputable refurbishers guarantee a minimum of 80%. At this level you may find you charge the phone more frequently than when it was new.
Below 80%: Apple considers below 80% to be significantly degraded and recommends battery service. Most reputable refurbishers will not sell below 80%, and if one does, you should negotiate a lower price or avoid the purchase.
Below 70%: Unacceptable for a daily driver. A phone in this state should only be purchased for parts or if a battery replacement is included in the deal.
How to check battery health on an iPhone
Checking battery health takes 30 seconds and should be the first thing you do after receiving any refurbished iPhone.
Go to Settings → Battery (see Apple's official battery health guide for full details) → Battery Health & Charging. The percentage shown next to Maximum Capacity is your battery health. This screen also shows whether the battery is supporting normal peak performance or whether it has been limited.
If the screen shows "Your battery's health is significantly degraded" — this is Apple's indication that the battery should be replaced. Do not accept this on a refurbished purchase.
What do reputable UK refurbishers guarantee?
All reputable UK certified refurbishers guarantee a minimum battery health of 80% on all devices they sell. This is the industry standard and should be clearly stated in their listing description.
Some retailers go further:
ur.co.uk replaces batteries as standard on Grade B and Grade C devices, meaning many refurbished iPhones from ur.co.uk arrive with battery health close to 100% even on budget grades.
IncTablet guarantees 80%+ and tests battery health as part of their certification process.
Back Market requires all listed devices to have 80%+ battery health from their approved refurbishers.
musicMagpie guarantees 80%+ across all grades.
If a retailer does not clearly state their battery health guarantee, ask before purchasing. If they cannot confirm a minimum of 80%, look elsewhere.
Should you buy a refurbished iPhone with 80% battery?
Yes — with caveats. 80% is the minimum acceptable, not the ideal. The question is how you use your phone.
Light users (calls, messages, email, occasional browsing): 80% battery health is perfectly fine. You will charge once per day and rarely notice the difference from a new battery.
Moderate users (social media, maps, video, some gaming): 80–85% is workable but you may find yourself reaching for a charger earlier in the evening than you would with a new phone.
Heavy users (streaming, gaming, always-on apps, business use): 85%+ is preferable. At 80%, a heavy user may need to charge during the day.
Travelling or long days away from a charger: higher battery health is more important. Consider upgrading the grade to get a device with higher battery health, or confirm the retailer's battery replacement policy.
Can you replace a refurbished iPhone battery?
Yes, and it is often cost-effective. Battery replacement brings health back to 100% and significantly extends the useful life of the device.
Apple official replacement: £65–95 depending on model, at an Apple Store or Apple Authorised Service Provider. Uses genuine Apple batteries. Comes with Apple's 90-day warranty on the repair. Visit apple.com/uk/support/battery-service to book.
Third-party repair shop: £30–60 depending on model. Uses aftermarket batteries which are cheaper but may not have exactly the same performance characteristics as genuine Apple batteries. Quality varies by shop — look for Google reviews and ask about the battery brand used.
DIY replacement: possible with the right tools and a kit from suppliers like iFixit. Not recommended for most people — requires careful disassembly and risks damaging the device.
The economics of battery replacement depend on the device. For an iPhone 13 worth £120 refurbished, a £40 third-party battery replacement is almost always worth it if battery health is the only issue. For an older iPhone 11 worth £60, it may not be.
Does battery health affect performance?
Yes. Apple introduced performance management in iOS 11.3 to prevent unexpected shutdowns on iPhones with degraded batteries. When battery health drops below a certain threshold, iOS may limit peak processor performance to prevent shutdowns under load.
You can check whether performance management is active on your device in the same Battery Health screen. It will say "Performance management applied" if active. This is more likely on devices below 80% battery health but can also affect devices in the 80–85% range that have experienced unexpected shutdowns.
A battery replacement resolves this — once the new battery is installed, performance management is disabled and the phone returns to full speed.
Tips for maintaining battery health on a refurbished iPhone
Once you have your refurbished iPhone, here is how to protect its battery health going forward:
Enable Optimised Battery Charging (Settings → Battery → Battery Health → Optimised Battery Charging). This learns your charging habits and avoids keeping the battery at 100% for extended periods, which degrades health faster.
Avoid charging to 100% and leaving plugged in overnight where possible. With Optimised Battery Charging enabled, iOS manages this automatically.
Avoid extreme temperatures. Heat is the biggest cause of battery degradation. Do not leave your phone in a hot car.
Use MagSafe and wireless charging sparingly if battery health is a concern — wireless charging generates more heat than wired charging and can accelerate degradation over time.
Replace when health drops below 80%. At that point, a battery replacement is almost always cost-effective before the phone loses value further.
Frequently asked questions
What battery health should a refurbished iPhone have?
A minimum of 80%, guaranteed in writing by the retailer. Above 85% is preferable for moderate to heavy users.
Will a refurbished iPhone battery degrade faster?
No. Battery degradation is about charge cycles, not age. A refurbished iPhone with 85% battery health will degrade at the same rate as a new phone from 100%.
How many charge cycles does a new iPhone battery last?
Apple rates iPhone batteries to retain 80% capacity after 500 charge cycles. A charge cycle is defined as using 100% of battery capacity, not necessarily a single charge from 0–100%.
Is there any way to check battery health before buying?
Not remotely — you need the physical device. Ask the retailer for their battery health guarantee in writing before purchasing. Retailers listed on GadgetRank all provide battery health guarantees.
Compare certified refurbished iPhones with battery guarantees →