Phone battery dies in 4 hours — is it worth fixing or should you buy a new phone?
A £45 battery vs a £700 new phone. The maths is usually obvious — but here are the cases when replacing the whole phone makes sense.
Phone batteries die. The maximum capacity drops about 10–15% every year of normal use, and once it's under 80% you'll notice. The good news: replacing the battery is a £35–£60 fix on most modern phones, and the gain is dramatic — like getting your phone back from new.
How to know it's the battery (and not bad apps)
- iPhone: Settings → Battery → Battery Health. If Maximum Capacity is under 85%, replace.
- Android: Settings → Battery (varies). Look for "Battery Health" or use the AccuBattery app for a few days.
- Drains over 30% overnight while idle, or shuts off when there's still charge showing.
- Phone gets unusually hot in your hand or pocket.
When to replace the battery
If the phone is in good cosmetic condition, the software still gets updates, and the battery is the main complaint — replace it. £45 for a year or two more of life is the cheapest upgrade in tech.
When to replace the phone
- Phone is older than 5 years and security updates have stopped.
- You also have a cracked screen, dodgy charging port, or other issues that add up.
- You want features the old phone can't do (5G, modern camera, MagSafe).
The trade-in maths
If you're upgrading, your old phone is worth money even with a dying battery. iPhone 11 with a tired battery still trades in for ~£90. With a fresh battery first: £130. The £45 spend often pays for itself.