Battery capacity in a specification tells you about the model when new. Battery health is about the particular battery now. Neither gives a reliable promise of how many hours your own phone will last.
Size and health are different
A capacity such as 5,000 mAh describes the size of the battery. A health reading such as 85% is an estimate of its remaining capacity compared with when it was new. Screen use, signal, apps and settings also affect the time between charges.
Apple explains that rechargeable batteries lose capacity with age and use, and that battery condition can affect performance. It also warns that health information may be inaccurate when an iPhone cannot verify the battery. See Apple’s battery and performance guide.
Ask four questions about a refurbished phone
- What minimum battery health, if any, does the seller promise?
- Does that promise apply to this condition grade and this exact offer?
- Is the battery original, replaced or simply tested?
- What will the seller do if it fails the promise or develops a fault?
Do not assume that “Excellent” condition means a new battery. A cosmetic grade may only describe marks and scratches. There is no single battery threshold used by every shop.
Compare the cost of the whole purchase
Ask for a replacement quote if battery life is a concern. A £170 phone plus a £70 battery service totals £240; that is an illustrative calculation, not a repair price. Compare it with a dearer offer that has a clearer battery promise, then weigh up the warranty and time without the phone.
Check it during the return period
Read the battery information available on the phone and use it normally for calls, maps and your usual apps. Record any fault and contact the seller. Avoid drawing a conclusion from a single first-day charge while the phone is setting up and downloading data.
Compare refurbished offers and use the full buying checklist before ordering.
Reviewed 29 October 2026 · Here4Mobiles