Your phone was at 40% a minute ago, and now it’s dead. Or it barely makes it to lunch. Or it only works while it’s plugged in. Battery trouble is the most common reason people think they need a new phone, and in many cases they don’t. A new battery can make a phone feel close to new again.

This guide explains why phone batteries wear out, the signs to watch for, how to check your battery’s health on iPhone, Samsung and Pixel, what to do right away if a battery is swollen, and when a replacement is (and isn’t) worth it.

In this article: Why batteries wear out · Signs your battery is failing · How to check battery health · Swollen battery: what to do now · DIY vs professional replacement · When it’s not worth replacing · FAQ

Why phone batteries wear out

Phones use lithium-ion batteries. Each time you charge and drain the battery, tiny chemical changes happen inside that slowly reduce how much energy it can hold. One “charge cycle” means using 100% of the battery’s capacity in total, for example 50% one day and 50% the next.

Apple says iPhone 14 models and earlier are designed to keep 80% of their original capacity after 500 complete cycles, and iPhone 15 models and later after 1,000 cycles, under ideal conditions (Apple Support). For most people, that’s roughly two to three years of daily use before the battery feels noticeably weaker.

What speeds up aging:

• Heat. Leaving a phone in a hot car, gaming while charging, or charging under a pillow all age a battery faster.
• Cheap or damaged chargers that deliver unstable power.
• Physical damage from drops or bending.

What about cold? Cold weather can make a battery drain fast or make the phone shut off, but that’s usually temporary. Apple’s recommended range for using an iPhone is 32° to 95° F (0° to 35° C). Warm the phone up to room temperature and it should behave normally again. If it still shuts off at 20–30% indoors, the battery is worn.

Signs your battery is failing

• It drains much faster than it used to, even with the same apps.
• It shuts down suddenly with charge still showing, often at 10–30%.
• The phone feels slower. iPhones can limit peak performance after an unexpected shutdown to prevent more shutdowns.
• It gets hot during normal use or charging.
• It only works while plugged in, or the percentage jumps around.
• The screen is lifting, the back is bulging, or the case no longer fits. This means swelling. Read the next section now.

How to check your battery’s health

• iPhone: Settings → Battery → Battery Health (Battery Health & Charging on some versions). You’ll see Maximum Capacity and, on newer models, the cycle count. A “Service” message or capacity below about 80% means it’s time. If performance management has been applied, that’s another sign (Apple Support).
• Samsung Galaxy: open the Samsung Members app → Support → Phone diagnostics → Battery status. Samsung rates it Normal, Weak or Bad (Samsung Support).
• Google Pixel: on newer Pixels, go to Settings → Battery → Battery health.

Swollen battery: what to do right now

A swollen battery means gas is building up inside it. It can push the screen out, crack the glass, bend the frame, and in rare cases catch fire. Samsung’s advice is clear: stop using the device right away, stop charging it, and don’t try to fix it yourself.

1. Unplug it and stop charging it.
2. Power it off if you can do it without pressing hard on the screen.
3. Don’t squeeze, bend or puncture it, and don’t try to push the screen back into place.
4. Keep it away from heat and anything flammable, and don’t leave it charging overnight or in a hot car.
5. Don’t throw it in the trash. Lithium batteries need proper recycling.
6. Bring it in. We can safely remove the battery and replace it, and recycle the old one properly.

Myths vs facts

• Myth: “Drain it to 0% every time to keep it healthy.” Fact: that was true of old nickel batteries. Lithium-ion batteries don’t need it, and running to empty often adds wear.
• Myth: “Charging overnight ruins the battery.” Fact: modern phones manage overnight charging, and iPhones and many Android phones offer optimized or limited charging. Heat is the bigger problem, so don’t charge under a pillow.
• Myth: “A new phone is the only fix for bad battery life.” Fact: if the rest of the phone is fine, a new battery is usually the cheapest way to get a full day back.

DIY vs professional battery replacement

Battery kits are sold online, but this is one of the riskier DIY repairs:

• Fire risk. Batteries are held in with strong adhesive. Prying them out with a metal tool can puncture the cell, which can start a fire within seconds.
• Glued screens and thin cables. On most phones, you have to remove the screen or back glass first, with the same risks as a screen repair.
• Quality. Cheap batteries may have less capacity than advertised or wear out quickly.
• Warning messages. On iPhone XS and later, a battery that can’t be verified as genuine may show an “Unable to verify” message, and battery health readings may not be accurate (Apple Support).

A professional replacement uses the right tools to release the adhesive safely, a quality battery, and new adhesive and seals, and the phone is tested before you leave.

How long a battery replacement takes

At My Cellphone Repairs, most battery replacements on iPhone, Samsung Galaxy and Google Pixel take 15–30 minutes while you wait, and most repairs are done the same day.

When it’s not worth replacing

• The phone no longer gets security updates, so you’d be putting a new battery in a phone that’s becoming unsafe to use online.
• It also needs a screen, port or water damage repair, and the total is close to the price of a newer phone.
• Your battery health is still high (for example, above 90%), and the drain is caused by an app or setting rather than the battery.

Not sure? Our diagnosis is free, and we’ll tell you honestly whether a battery will fix your problem.

Get a new battery at My Cellphone Repairs

Walk in or book online at one of our stores in Maryland, Michigan, Pennsylvania, New Jersey and Virginia. Diagnosis is free, and most battery replacements take 15–30 minutes. Check the price for your model.

BOOK A BATTERY REPLACEMENT

We also fix tablets and computers

iPad dying fast? Laptop only works plugged in? We also do iPad battery replacement, Samsung tablet repair and laptop and MacBook battery replacement at the same stores, with the same free diagnosis.

Questions people ask

How do I know if my phone needs a new battery?
Fast drain, sudden shutdowns with charge left, slowdowns, heat, or battery health below about 80%. Bring it in and we’ll test it for free.

Is a swollen phone battery dangerous?
Yes. Stop using and charging the phone, don’t press on it, and bring it in so the battery can be removed safely.

How long does a battery replacement take?
Most battery replacements at My Cellphone Repairs take 15–30 minutes. Book a time.

Why does my phone die in the cold?
Cold slows the chemistry inside the battery. It’s usually temporary, but a worn battery is much more likely to shut down in cold weather.

Sources

• Apple Support: iPhone battery and performance
• Samsung Support: Check device status and run diagnostics
• MacRumors: Apple raises iPhone 15 battery lifespan to 1,000 cycles

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