How to Calibrate Your Android's Battery

Reset your Android battery when it's giving you trouble

Often when a phone's battery is acting oddly, people assume it's time for a new phone. But that's not always the case. Instead, you may simply need to calibrate your battery. Here's why you should perform an Android battery calibration, and how to do it.

Why Do I Need to Calibrate My Battery?

Batteries will inevitably see a decrease in performance over time. That's just simple physics: As ions flow between the anode and the cathode of a battery, the cathode wears out. In fact, this happens even if you leave your phone in a drawer. And it applies to all batteries, from your car to your phone.

However, this performance decrease is rarely as dramatic as your phone may make it out to be. You may see statements that batteries will last for “only” 500 charge cycles, but like any product, performance can vary from battery to battery and even between individual batteries of the same type.

It also depends on your charging habits; if you charge your phone to 100%, and then don't use your phone very often, letting it discharge all the way down to almost empty, you'll experience very different battery life than a phone you use constantly with the screen on full blast.

A smartphone with a dying battery
Artur Debat/Getty Images

As a result, your phone's battery tracking tools and the battery itself are usually at least somewhat out of step with each other. This desynchronization is common as batteries lose slight amounts of performance. Yet even small amounts of desynchronization can wreak havoc; imagine if your gas tank indicated it was “full” when it was really only 75% full. You'd probably be fine most of the time, but when you push it is where you run into trouble.

Adding to the problem, as your phone struggles to make sense of what it's being told, bad data piles up, causing errors and making it more difficult to get an accurate reading. Calibration will “clear the decks” and make this easier to do by allowing your phone to figure out what's 0% and what's 100%.

When Should I Calibrate My Battery?

Ideally you should calibrate your battery every two to three months, after your phone has been exposed to extreme cold or extreme heat, or if your phone is showing the following symptoms:

  • Showing a full charge, then suddenly dropping extremely low.
  • Staying “stuck” on one charge percentage for long periods of time.
  • Showing the same charge percentage after both charging and discharging.
  • Discharging more quickly than expected.
  • Refusing to charge.
  • Needing to charge your phone multiple times a day, or needing to leave it plugged in during the day.
  • Reporting battery issues via pop-up even though the phone is working fine otherwise.

Before You Calibrate Your Battery

If possible, before calibration, you should visually inspect your battery. If you see bulges or leaks, or if your phone's casing is beginning to loosen or crack, your battery itself is damaged and will need to be replaced. This is especially true if there's a noticeable decline in battery performance immediately after dropping your phone.

You should also clear your Android phone's cache and, if available, run any and all available firmware and operating system updates. This will help with the calibration process and may address other issues.

Do I Need to Root My Phone to Calibrate My Battery?

You may read that rooting your device and deleting a specific file, usually called batterystats.bin, is the only way to truly calibrate your battery. This isn't accurate.

What, precisely, this file does varies from company and company, but generally it stores the database that your phone's battery indicator uses to inform you about your phone's charge. Deleting this file may be slightly quicker, and it's usually harmless. 

But unless your device is already rooted, the procedure for calibrating your battery is simple enough that it's likely an unnecessary step. And if you're not sure how your phone uses this file, or any file, you should leave it alone.

How to Calibrate Your Android's Battery

You may want to coordinate this process while you're near a landline, staying at home for the day, or otherwise not in need of your phone. Also do not leave your phone uncharged for long periods of time. Doing so may force it into “deep discharge,” which wears out the battery completely and will require it to be replaced.

You can use your phone normally during the process of discharging the battery.

  1. Let your phone discharge its battery until it turns itself off.

  2. Turn your phone on, and let it turn itself off again.

  3. Leaving your phone off, plug it into a charger and leave it alone until it indicates that it's 100% charged.

  4. Unplug your phone and turn it on, then check the battery indicator to see if the battery is at 100%. If so, you're all set. If not, plug it back in until it says it's charged to 100%. You may need to repeat these steps several times, to get your phone as close to 100% as possible.

    If your phone doesn't charge beyond the initial percentage you see, this may be an indicator of more complicated battery issues. Take it to a certified repair shop or carrier store.

  5. Once you're satisfied it's as charged as it will get, allow it to run down until it turns itself off.  

  6. Fully charge the phone while it's off. Turn it on, and your battery should be calibrated.