How to know when your phone battery is failing

Your phone battery is failing when it no longer holds a charge through a normal day of use, shuts down unexpectedly even when the battery indicator shows 20 or 30 percent, or charges to only 80 percent no matter how long you leave it plugged in. These are the three clearest signals that the battery itself—not the charger or software—has degraded enough to warrant replacement.

Lithium-ion batteries, which power nearly all smartphones, lose capacity over time. Each charge cycle (a full drain and recharge) wears the battery down slightly. After roughly 500 to 1,000 full cycles, most phone batteries retain only 80 percent of their original capacity. After 1,500 to 2,000 cycles, they often drop to 60 to 70 percent. If your phone is two to three years old and you charge it daily, you are likely in this range.

The difference between a degraded battery and a phone that straightforward needs charging is straightforward: a degraded battery loses capacity permanently, while a fully charged phone works normally. If your phone works fine all day after a full charge, the battery is still healthy. If it drains to zero by mid-afternoon even after a full overnight charge, or if it shuts down at 30 percent, the battery has degraded.

Key Takeaways

  • Replace your battery when it no longer lasts a full day of normal use, shuts down unexpectedly above 20 percent charge, or refuses to charge past 80 percent.
  • Most phone batteries degrade noticeably after 500 to 1,000 full charge cycles, which takes roughly two to three years of daily charging.
  • You can check your battery's health on iPhone through Settings > Battery > Battery Health & Charging, or on Android through Settings > Battery > Battery Usage or a third-party app.
  • Replacing a battery costs between $50 and $150 depending on your phone model and whether you use the manufacturer or a third-party repair shop.
  • A replacement battery usually restores your phone to near-original performance and extends its usable life by two to three more years.

Check your battery health before deciding

Both iPhone and Android phones let you see your battery's actual health percentage, which tells you whether replacement is necessary or whether something else is draining power.

On an iPhone running iOS 16 or later, go to Settings > Battery > Battery Health & Charging. You will see "Maximum Capacity" as a percentage—this is how much charge your battery can hold compared to when it was new. If it shows 80 percent or higher, your battery is still within normal range. If it shows 70 to 79 percent, it is degraded but may still work for another year. Below 70 percent, replacement is usually worth considering. You will also see "Condition" listed as either "Normal" or "Service Recommended"—if it says "Service Recommended," the battery has degraded enough that Apple suggests replacement.

On Android, the process varies by manufacturer. Samsung phones show battery health in Settings > Device Care > Battery, though the percentage display is less detailed than iPhone. Google Pixel phones do not display a health percentage in settings. For most Android phones, you can read a free third-party app like AccuBattery or Battery Health from the Google Play Store, which estimates capacity by monitoring charge cycles and power draw. These apps are not as precise as manufacturer tools but give you a useful ballpark figure.

Other reasons your phone might drain quickly

Before you replace the battery, rule out software or settings that can mimic battery failure. A phone with a degraded battery drains steadily throughout the day, but a phone with a software problem or a power-hungry app might drain in bursts or only when you use certain features.

Check Settings > Battery > Battery Usage (or Battery Saver on iPhone) to see which apps are consuming the most power. If one app is using 30 or 40 percent of your battery while others use 2 to 5 percent, that app may be the culprit—try uninstalling it or clearing its cache. Background app refresh, location services, and screen brightness also drain batteries quickly; turning these off in settings can add hours to your phone's runtime without replacing anything.

If your phone is hot to the touch, shuts down suddenly, or drains only when you use the camera or video, the issue may be the charger, the charging port, or a hardware fault rather than the battery itself. In those cases, a technician should diagnose before you pay for a battery replacement.

When replacement makes financial sense

A battery replacement costs between $50 and $150 depending on your phone model and where you have it done. Apple charges $69 to $99 for iPhone batteries depending on the model. Samsung charges $60 to $90. Third-party repair shops like iFixit or local independent technicians often charge $40 to $80 and may be faster, though they do not carry the same warranty as the manufacturer.

Replacing the battery makes sense if your phone is otherwise in good condition and you plan to keep it for another two to three years. A new battery typically restores your phone to near-original performance and costs far less than buying a new phone. If your phone is already four or five years old, has a cracked screen, or is running an operating system that no longer receives updates, you may be better off replacing the phone itself rather than investing in a battery.

If your phone is still under warranty or AppleCare coverage, battery replacement may be free or discounted. Check your coverage before paying out of pocket.

Where to have the battery replaced

You have three main options: the phone manufacturer's official service center, an authorized third-party repair shop, or an independent local technician.

Official manufacturer service (Apple Store, Samsung Service Center, etc.) takes one to three days, includes a warranty on the replacement battery, and uses genuine parts. The downside is cost—Apple charges more than most third-party shops—and you may need an appointment.

Authorized third-party shops like Best Buy's Geek Squad or carrier stores (Verizon, AT&T) also use genuine or certified parts and offer warranties, usually at a lower price than the manufacturer. Turnaround is typically same-day to two days.

Independent local repair shops are often the cheapest and fastest option, sometimes replacing the battery while you wait. The trade-off is that they may use third-party batteries rather than genuine ones, and the warranty is usually shorter (30 to 90 days rather than one year). Read reviews on Google or Yelp before choosing a local shop, and ask whether they use genuine or third-party batteries before you commit.

What to expect after replacement

A new battery should restore your phone to roughly the performance it had when new—a full day of use on a single charge, no unexpected shutdowns, and the ability to charge to 100 percent. You may notice the phone feels slightly faster because it is no longer throttling performance to protect a weak battery, though this is a side effect rather than the battery itself making the phone faster.

The replacement battery will begin to degrade when ready, but at the normal rate. You should expect another two to three years of healthy battery life before you need to consider replacement again. If the new battery drains quickly or fails within a few weeks, contact the shop or manufacturer—defective batteries are rare but do happen, and most come with a warranty covering early failure.

Frequently Asked Questions

Can I replace my phone battery myself?

You can on some phones, but it is risky. iPhones require removing the screen, which is difficult without the right tools and can crack the display. Android phones vary—some have removable backs and user-replaceable batteries, but most do not. If you attempt it and damage the phone, repair costs will exceed what a technician would have charged. Unless you have done phone repairs before, professional replacement is safer.

Does using my phone while charging damage the battery?

Using your phone while charging generates heat, which does wear the battery faster over time, but the effect is small. Occasional use while charging is fine. Leaving your phone plugged in for hours after it reaches 100 percent, or charging it in a hot environment, causes more wear. Modern phones have safeguards that slow charging once the battery is full, so leaving it plugged in overnight is not as harmful as it was with older batteries.

Will a new battery make my old phone feel new again?

A new battery will restore battery life and eliminate unexpected shutdowns, but it will not speed up a slow processor or fix a cracked screen. If your phone feels slow, that is usually a software or storage issue, not a battery problem. A battery replacement is worth doing if the phone otherwise works well; if it is slow, freezes, or has other hardware problems, those will remain after the battery is replaced.

How long does a battery replacement take?

Official service centers typically take one to three business days. Authorized third-party shops often do it same-day or next-day. Independent local shops may replace it while you wait, sometimes in under an hour. Call ahead to ask about turnaround time before you drop off your phone.

Is it worth replacing the battery in a five-year-old phone?

Only if the phone otherwise works well and you plan to keep it for at least another year or two. If the screen is cracked, the phone is slow, or it no longer receives software updates, the cost of a battery replacement is better spent toward a new phone. If the phone is in good condition and you like it, a $60 to $100 battery replacement can extend its life by two to three years.