A phone that used to last all day and now needs charging by mid-afternoon is one of the most common complaints we hear. Sometimes the battery has simply worn out. Just as often, something on the phone is using more power than it should. Working out which is which saves you time and money.
Start with your battery health reading
Phone batteries are lithium-ion, and every one of them gradually loses capacity as it goes through charge cycles. After a couple of years, a battery can hold noticeably less charge than it did when new.
- iPhone: go to Settings, then Battery, then Battery Health (on newer versions, Battery Health & Charging). It shows the maximum capacity compared with when the battery was new, and whether the battery is affecting performance.
- Android: this varies by make. Some phones show battery health under Settings, then Battery. Samsung phones can run a battery check through the Samsung Members app's diagnostics. Some phones don't show a health figure at all.
A low reading, or a message saying the battery is significantly degraded or needs service, is a strong sign the battery itself is the problem. A healthy reading points you towards settings and apps instead.
Check what's using the battery
Both iPhone and Android show battery use by app in the Battery section of Settings. Look for an app that has used a large share of battery even though you've hardly opened it, or one with lots of background activity. That app may be stuck, misbehaving or syncing constantly. Updating it, force-closing it or removing and reinstalling it often helps.
The usual suspects
- Screen brightness and always-on display. The screen is usually the biggest single power user. Auto-brightness and a shorter screen timeout make a real difference.
- Weak signal. In poor coverage the phone works harder to stay connected, which drains the battery. If you're in a weak area most of the day, switching to Wi-Fi calling where available can help.
- Location services. Apps that track location all the time cost battery. Set apps to use location only while you're using them, unless they genuinely need it.
- Background refresh and syncing. Email, cloud photo uploads and social apps refreshing in the background all add up.
- Heavy use. Gaming, video streaming, navigation, video calls and using the phone as a hotspot are all demanding.
- Just after an update or a new setup. For a day or two after a major update or restoring from a backup, phones often do a lot of background work such as indexing photos, so battery life can dip temporarily.
Temperature makes a big difference
Cold weather temporarily reduces how much power a battery can deliver, which is why phones sometimes shut down outside on a freezing day while showing plenty of charge left. That usually recovers once the phone warms up.
Heat is worse in the long run. Regularly letting your phone get hot, for example by leaving it on a car dashboard, charging it under a pillow or gaming while it charges, speeds up permanent battery wear. If your phone often gets uncomfortably hot, read our guide to phone overheating causes and when to get help.
Charging habits
You don't need to run your battery down to zero before charging; modern batteries don't benefit from that. Many phones now include features that slow charging overnight or stop at around 80 to 85 per cent to reduce wear, such as Optimised Battery Charging on iPhone or battery protection settings on Samsung and other Android phones. If your phone seems to stop charging at 80 per cent, check those settings before assuming there's a fault.
Use a decent-quality charger and cable. If your phone charges very slowly or not at all, our guide to phone charging problems walks through the checks.
Signs the battery itself may need checking
- The battery health reading is low, or the phone says the battery needs service.
- The phone shuts off unexpectedly, often at 20 or 30 per cent.
- The percentage jumps around, for example from 40 to 10 per cent in minutes.
- It drains quickly even when you're barely using it and no app stands out.
- The phone gets warm when idle and not charging.
- The phone has slowed down noticeably, which some phones do to protect a worn battery.
A swollen battery is a safety issue. If the screen is lifting, the back is bulging or the phone rocks on a flat surface, stop charging it, don't press on it and get it checked promptly.
Replace the battery or replace the phone?
If the rest of the phone works well and still gets software updates, a new battery can make an older phone feel much more usable again, often for far less than a new handset. There's more on this in the battery replacement section of our repairs page.
