Signs your phone battery needs replacing (and how to check)
Quick answer: Replace the battery when its health is below 80% of its original capacity, when the phone shuts down with charge still showing, or when it drains much faster than it used to. A swollen battery that lifts the screen or back needs replacing straight away. Check health in Settings, then Battery.
Video not loading? Open the video on YouTube. It may not match your exact model; check the written guidance and device scope before following it.
The signs
1It drains much faster than it used to
If a full charge used to last the day and now runs out by lunchtime with the same use, the battery has lost capacity. Check first that a new app isn't to blame: Settings, then Battery, shows which apps use the most.
2It shuts down with charge left
A phone that switches off at 20% or 30%, especially in the cold or when you open the camera, has a worn battery that can't deliver power on demand.
3It has slowed down
Apple says an iPhone with an aged battery may manage performance to avoid shutdowns. You may notice slower app launches, lower frame rates, a dimmer screen or quieter speaker.
4The phone is bulging
If the screen or back panel is lifting, or the phone rocks on a flat table, the battery is swelling. Stop charging it, don't press on it, and get it replaced. This one is a safety issue, not just performance.
How to check battery health
5iPhone
- iPhone 15 and later: Settings, then Battery, then Battery Health.
- iPhone 11 to 14: Settings, then Battery, then Battery Health & Charging.
Look at Maximum Capacity. Apple designs iPhone 14 and earlier to keep 80% capacity after 500 full charge cycles, and iPhone 15 and later after 1,000.
6Google Pixel
On a Pixel 8a or newer: Settings, then Battery, then Battery health. Normal is fine. Reduced means capacity is below 80% of new, and Google recommends considering a replacement. Tap Battery capacity for the estimate. Older Pixels don't show a health status.
7Samsung Galaxy
Open the Samsung Members app and run its phone diagnostics, which include a battery check.
When to replace it
Both Apple and Google use the same line: below 80% of original capacity is the point to consider a new battery. Google also recommends replacement after 800 charge cycles on Pixel 3 to Pixel 8 Pro and Pixel Fold, and 1,000 on Pixel 8a and later.
Use the maker's own repair service or an authorised repairer. A cheap unbranded battery can show as "unknown" in settings and may not last.
Make the new battery last
Avoid leaving the phone in hot cars or the sun, and don't charge it under a pillow or in a thick case for hours. Heat ages batteries faster than anything else.
What to tell support
Keep a short record of your exact device model, software or app version, the symptom or error text, and which steps you tried. Note what changed after each step. You can print this page for reference.
Do not include passwords, recovery codes or private account details in public comments.
Sources
Video by FixIt Mobile on YouTube. See the linked sources for current manufacturer guidance. Menu names and available features can vary by model and software version. How we check fixes.