How to Check iPhone Battery Health Before You Buy

Battery health is the single most important thing to check before buying any pre-owned iPhone — and the number one thing private sellers hope you won't ask about. An iPhone can look brand new and still have a battery that's barely holding a charge by lunchtime. Here's exactly how to check it, what the numbers mean, and why it matters more than almost any other spec.

How to Check iPhone Battery Health

If you're buying from a private seller and can inspect the phone in person (or ask for a screen recording), here's how to check:

  1. Open Settings
  2. Tap Battery
  3. Tap Battery Health & Charging
  4. Look at the Maximum Capacity percentage

That percentage tells you how much charge the battery can currently hold compared to when it was brand new. A battery at 100% Maximum Capacity holds a full charge exactly as designed. As batteries age and go through charge cycles, that number naturally drops.

What's a "Good" Battery Health Percentage?

  • 90–100% — Excellent, close to new performance
  • 85–89% — Still solid, minor daily impact
  • 80–84% — Noticeable decline; you'll likely need a top-up by evening
  • Below 80% — Apple itself flags this as degraded; expect unexpected shutdowns, slower performance under load, and a battery that drains fast

This is exactly why Digi Merchant guarantees a minimum of 85% battery health on every device we sell. Anything below that isn't something we consider good enough to put in front of a customer — even at a discount.

Why Private Sellers Rarely Mention This

Battery health isn't visible from the outside. A phone can have a flawless screen and body and still be sitting at 76% battery health — and most Gumtree or Facebook Marketplace listings simply won't mention it, because most buyers don't know to ask. By the time you find out, you've already paid.

This is one of the most common regrets we hear from customers who previously bought privately: the phone "looked perfect" but needed charging twice a day within weeks of buying it.

Can Battery Health Be Faked or Hidden?

Not easily — Maximum Capacity is calculated by the device itself based on real usage data, not something a seller can simply reset from the Settings app. However, there are a few things to watch for:

  • A replaced battery from an unofficial source may show a health percentage but behave unpredictably, since third-party batteries aren't always accurately read by iOS and they will show an "unknown part" message.
  • "Service" warnings in Battery Health mean the battery isn't being verified as genuine — a major red flag if you see this on a listing
  • No battery health screenshot at all in a private listing is itself a warning sign — legitimate sellers with nothing to hide will usually show you

How Digi Merchant Handles This Differently

Every device we sell goes through a battery health check as part of our six-step refurbishment process, before it's ever listed. If a unit doesn't meet our 85%+ threshold, it doesn't go out under our name as-is. This is listed transparently on every product page, so you know the exact battery condition before you buy — not after.

The Bottom Line

Battery health should never be a guessing game when you're spending money on a phone. Before buying pre-owned from anyone — us included — the Maximum Capacity percentage must we known. If a seller can't or won't provide it, that tells you everything you need to know.

Browse our current iPhone stock at digimerchant.co.za, where every listing shows battery health upfront, backed by our 85%+ guarantee and 6-month warranty.

Not sure which iPhone model fits your budget and battery needs? Reach out to our team — we're happy to walk you through the options before you buy.

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