Your phone suddenly can't make it through the day, and the obvious assumption is a worn-out battery. But sometimes the real issue isn't the battery's actual health - it's the phone's reading of it. Here's how to tell the difference before you spend on a replacement.

Check the actual battery health number

On iPhone, go to Settings > Battery > Battery Health & Charging, and check Maximum Capacity. Anything below around 80% means the battery has genuinely lost a meaningful chunk of its original capacity. On Android, the equivalent is usually in Settings > Battery > Battery Health, though the exact menu varies by manufacturer.

Signs it's genuine degradation

• The percentage drops steadily and predictably through the day
• The phone gets noticeably warm during normal use
• Performance slows or the phone throttles itself under load
• The battery percentage matches how the phone actually behaves

Signs it's miscalibration, not degradation

• The percentage jumps suddenly - say, from 40% to 15% - with no unusual activity
• The phone shuts down unexpectedly while still showing charge remaining
• Battery percentage behaves erratically after a recent software update

How to recalibrate

If it looks like miscalibration, let the phone run down to 0% and shut off naturally, then charge it to 100% in one uninterrupted session, ideally powered off. This resets the phone's internal estimate of the battery's charge curve and often fixes an inaccurate reading without any hardware changes.

If it's genuine wear

If the health reading confirms real degradation, a battery replacement is usually the cheapest, highest-impact repair available - often solving the problem entirely without touching anything else in the phone.

Repatch can check your phone's actual battery health and swap it out if needed. A courier collects your device from home or work, a professional technician does the job, and it's returned to you, often within 2 hours.