Battery health and what it does to your phone's price

Of all the condition questions, battery health is the one people worry about most and the one that changes least. Here is what the number is, where it comes from, and what it actually does to a quote.

Where the figure lives

On an iPhone: Settings → Battery → Battery Health & Charging. The Maximum Capacity percentage at the top compares what the battery holds today against what it held new. That is the number you will be asked for when you sell.

On an iPad or a Mac there is no percentage in the same place; on a Mac, System Settings → General → About → System Report → Power gives a cycle count and a condition line instead. On an Android phone there is no standard figure at all — which is why the questions there are about behaviour rather than a number.

What the number means

A lithium battery loses capacity with every full charge cycle. Apple designs its phone batteries to keep about 80% of their original capacity after 500 full cycles — recent models are rated for 1,000 — and that 80% figure is where Apple itself says a battery is worth replacing. The whole resale market has settled on the same line.

So, roughly:

• 90% and above: healthy, typical of a phone up to about two years old.
• 80–89%: normal wear. Treated as a healthy battery.
• Below 80%: a deduction, and it grows as the number falls. Never a refusal.

Peak Performance Capability matters too. If iOS has ever throttled the phone after an unexpected shutdown, it says so on that same screen, and that is worth reading before you answer.

A replaced battery

Replacing a battery is not held against a phone. What is asked is *who* replaced it: Settings → General → About → Parts & Service History will show a battery fitted outside Apple or an authorised centre as an unknown part, and it is priced as a non-original battery. That is a smaller deduction than a badly worn original in most cases, but it is not nothing, and it is checked at the door, so answer it as it stands.

Should you replace the battery before selling?

Almost never. An out-of-warranty battery replacement costs more than the deduction it removes, and if it is not done by Apple it introduces a non-original part into the phone. Declare the figure and let the quote handle it.

Android

No percentage, so three behavioural questions: does the battery drain noticeably fast, does the phone shut down before it reaches zero, and has the battery begun to swell — a back panel that no longer sits flat, or a screen lifting at one edge. A swollen battery is priced as a fault, and it is the one fault we would rather you did not sit on for another six months.

What it is worth remembering

The battery is one line in a quote that also weighs the screen, the body, every function and the accessories. It is rarely the thing that decides the number. What actually decides the price puts it in order — or see your phone's own figure on the sell page.