What "battery health" actually means
Battery health is a simple measure: how much charge a battery can still hold compared to when it was brand new. A phone at 100% battery health holds its full original capacity. A phone at 80% has lost a fifth of that capacity to normal wear from charge cycles and age.
It's a different measurement from battery life — how long a phone lasts between charges in daily use — though the two are closely related. If you want the full breakdown of how battery health and battery life interact across different phone models, we've covered that in detail in our complete guide to refurbished phone battery life.
The industry standard vs. the Zextons standard
Most UK refurbished phone retailers set their minimum battery health threshold at 80% — the same level Apple considers "optimal condition" for an iPhone battery. A smaller number of premium sellers go further, guaranteeing 85% or above.
| Seller standard | Minimum battery health |
|---|---|
| Typical UK refurbisher | 80% |
| Premium refurbishers | 80%+ |
| Zextons (new standard) | 85%+ |
We set our new minimum at 85% rather than simply matching the industry floor, because a few extra percentage points make a real difference in daily use — particularly for anyone who relies on their phone through a full working day without a charger nearby.
Why we raised our standard
This is the section to personalize with your real internal reason — for example: a new diagnostic testing partner, a stricter pass/fail threshold in your refurbishment process, a supplier or grading change, or a response to customer feedback. Whatever the actual driver was, this is the paragraph that will carry the most weight with readers and with AI search systems, since it's the one piece of information no competitor can copy. Drop in the real detail and I'll fold it in.
What this means for you as a buyer
- More consistent daily use. A battery at 85%+ is less likely to need a mid-afternoon top-up than one closer to the 80% floor.
- Longer runway before replacement. Starting higher means it takes longer to degrade to the point where a battery swap becomes worthwhile.
- A guarantee, not an estimate. Every device is tested individually before it's listed — 85%+ isn't an average across stock, it's the minimum any single phone you receive will have.
- Backed by our 18-month warranty. If a battery ever falls outside expected performance during that period, it's covered.
How we test it
Every phone that passes through Zextons goes through a diagnostic battery check as part of our refurbishment process, measuring actual remaining capacity against the device's original specification — not an estimate or a visual inspection. Phones that fall short of the 85% threshold are fitted with a replacement battery before they're eligible for sale.
Frequently asked questions
Is 85% battery health good for a refurbished phone?
Yes. It's above the 80% threshold most manufacturers and refurbishers treat as the baseline for "healthy" battery performance, and it sits close to the top tier of what premium refurbished sellers offer.
What's a good battery health percentage to look for when buying refurbished?
Most experts consider 80% and above acceptable for daily use. Above 85% is considered excellent. Zextons' 85%+ guarantee sits firmly in the strong end of that range.
Does Zextons replace batteries that fall below 85%?
Yes. Any device that doesn't meet the 85% minimum during testing is fitted with a replacement battery before it's listed for sale.
How is battery health measured on a Zextons refurbished phone?
We use diagnostic testing to measure the battery's actual remaining capacity against its original factory specification, rather than relying on an estimate or the phone's own onboard reading alone.
Browse refurbished phones
Looking for a refurbished phone you can trust from day one? Browse the full Zextons range, all covered by our 18-month warranty and free UK next-day delivery.