Lithium batteries wear with every charge cycle. After two or three years most phones hold noticeably less than they did new, and "my battery is terrible" becomes the reason for an upgrade. Often the cheaper fix is a battery.
Check the number
On an iPhone, Settings → Battery → Battery Health shows maximum capacity as a percentage of new. Recent Android phones show similar information under battery settings, and third-party apps can estimate it on those that do not. Below about 80%, the phone will feel it; below 70%, it is a daily problem.
What a new battery costs
Manufacturer and authorised repairers charge a fixed price that is a fraction of a new handset — typically well under £100 for most models, more for the largest flagships. Independent repairers are often cheaper still, though battery quality varies more. For a phone that is otherwise fine and still getting software updates, this is almost always the better value than upgrading.
When to replace the phone instead
- It has stopped receiving software and security updates, or will soon.
- Other things are failing too — charging port, screen, buttons.
- The repair cost is a large share of the phone's current value, which happens with older budget models.
Slowing the wear
Batteries age fastest when held at 100% or run flat, and when hot. Both iOS and Android now offer a charging limit (often 80%) or optimised charging that learns your routine; turn it on if you charge overnight. Avoid leaving the phone in a hot car or charging it under a pillow. None of this is dramatic, but together it can add a year to a battery's useful life.
Buying refurbished?
Battery health is the first thing to ask about. Good refurbishers state it or guarantee a minimum; some replace any battery below 80–85%. See our guide to refurbished grades for what else to check.