Updated October 3, 2026.
Six checks, in order
Each check takes a minute. Do them in order. Fast drain usually has a simple cause.
1. Turn down the brightness and always-on display
The screen uses more power than anything else in the phone. Pull the brightness down a notch. Turn on auto-brightness. If your phone has an always-on display, turn it off for a day. That alone can add real time.
2. Look at the battery screen
On iPhone: Settings, Battery, Battery Health. On Android: Settings, Battery. Menu names vary a little by brand.
"Maximum capacity" is how much charge the battery can hold now, compared to new. 100% is new. Under 80% is worn. A "Service" note means the phone itself is telling you the battery is done.
The same screen shows which apps used the most power. One app at the top with a big number? That is your next check.
3. Check background apps and location
Some apps keep working when you are not looking. Social, maps and games are the usual ones. On the battery screen, look for "background activity". Turn off background refresh for apps you do not need. Set location to "while using" instead of "always".
Do not swipe apps closed all day. It does not help, and it can make drain worse.
4. Weak signal and Wi-Fi hunting
The radio in your phone works hard when the signal is weak. One bar all day burns battery fast. So does a phone hunting for Wi-Fi it cannot find. In a spot with poor signal, try airplane mode for a while. Turn off Wi-Fi when you are out.
Drain fine at home and bad at work? This is often why.
5. Heat, cases and charging habits
Heat wears a battery down. A phone on a car dashboard, or gaming while it charges, gets hot. A thick case can trap that heat. Charge it in a cool spot. Keep it off the pillow at night. Try not to run it to zero every day.
None of this fixes a worn battery. It does help a good one last longer.
6. Age: batteries wear out
Batteries are a consumable, like tires. Every phone battery wears down with daily charging. After two or three years, a swap is normal. It is not a sign that something else is wrong.
If the phone works fine otherwise, a new battery often makes it feel new again. Read more on battery replacement.
Stop and bring it in now
Some signs mean come in soon. One means stop using it now.
The case is bulging, or the screen is lifting at an edge. That is a swollen battery. Do not press on it. Do not charge it. Bring it in as it is.
It shuts off at 30% or 40% with no warning. A worn battery cannot keep up when the phone asks for power.
It is hot while idle, sitting on the table doing nothing.
We test the battery for free. Then we tell you the price. You decide before we start. On popular phones, a battery swap takes about 15 minutes when the part is in stock. Read the 60-day warranty and no fix, no charge.
Reviewed September 2026. Menu names vary by model.