How to calibrate the battery on your Android phone or tablet

How do I know if my battery is the problem?

First of all, you need to identify why your battery performance has decreased: is it the Android system’s calibration or the battery itself? We’ll move onto calibration in the sections below, but you should check if your battery itself is damaged first.

If your phone has a removable battery cover, turn off your phone, remove the cover and inspect the battery. Look for bulges or leaks. In the image below, you’ll see what a normal battery looks like next to a swollen one. If your phone doesn’t sit flat on the table anymore, that could also be a sign of a swollen battery.

Should I calibrate the battery?

If you’re satisfied that the battery itself is not the problem, you can move on to the steps below. If you think your battery might be the problem (even after trying to recalibrate it), we’d advise you to take it to a repair shop for an expert’s opinion. If it turns out you need to replace the battery, go with an original or a reliable third-party battery. Buying a cheap knock-off battery only leads to more headaches in the long run.

Keep in mind that there are plenty of other things that can cause a battery to malfunction. If your phone doesn’t charge, there might be a problem with the port, so check our guide on what to do when a phone won’t charge.

If you’ve just updated the firmware on your phone, battery drain is a common complaint, so you might want to clear the cache partition on your device. Thankfully, we have plenty of guides on how to clear the cache on various devices.

What is calibrating a battery?

The Android operating system has a feature called Battery Stats, which keeps track of battery capacity, when it is full or empty. The problem is that it sometimes becomes corrupted and starts displaying data that isn’t real, which, for example, causes the phone to turn off before it reaches 0 percent. Calibrating your Android battery simply means getting the Android OS to correct this information so it is reflective of your actual battery levels once again.

It’s important to understand that you can’t actually calibrate the battery itself: it is, after all, just a cell that stores power and discharges. However, lithium-ion batteries do include a printed circuit board (PCB), which serves as a protection switch to stop them exploding or deep discharging.

Smartphone battery myths

Lithium-ion batteries don’t have a memory so there’s not much you need to do to keep them running as they should. The problem lies with how the Android system reads and displays the current capacity of the battery, not the battery itself.

The same goes for the myth that deleting the batterystats.bin file will magically recalibrate your battery. That file (on most devices anyway) simply stores data about what is using the battery when it is not being charged. It is also reset every time a battery is charged to over 80 percent and then disconnected from the charger.

The batterystats.bin file contains the info you see made prettier in the Battery section of your phone: it’s the Android system keeping track of your battery’s usage, per charge cycle. When we talk about battery calibration, it’s the percentage meter that gets out of whack, and that is what we need to fix.

How to calibrate an Android device battery without root access

The old ‘fully charge and discharge’ approach stands as one of the simplest ways to ‘recalibrate’ your Android battery. We’ve warned you in the past about low voltage problems in lithium batteries and the negative impacts of fully draining a battery on its lifespan and the same holds true here. But, if your phone battery is causing you real problems, it’s worth taking the risk.

Method 1

• Discharge your phone fully until it turns itself off.
• Turn it on again and let it turn itself off.
• Plug your phone into a charger and, without turning it on, let it charge until the on-screen or LED indicator says 100 percent.
• Unplug your charger.
• Turn your phone on. It’s likely that the battery indicator won’t say 100 percent, so plug the charger back in (leave your phone on) and continue charging until it says 100 percent on-screen as well.
• Unplug your phone and restart it. If it doesn’t say 100 percent, plug the charger back in until it says 100 percent on screen.
• Repeat this cycle until it says 100 percent (or as close as you think it’s going to get) when you start it up without it being plugged in.
• Now, let your battery discharge all the way down to 0 percent and let your phone turn off again.
• Fully charge the battery one more time without interruption and you should have reset the Android system’s battery percentage.

Remember that it is not recommended to perform this process regularly. Even when your battery is so dead your phone won’t even turn on, your battery still has enough reserve charge to avoid system damage. But you don’t want to poke the tiger with a stick. Perform this process once every three months at the most. If it is required more often than that, you have bigger problems at hand.

Put plainly: fully discharging a battery is bad for it. Trying to overload a battery is also bad for it. The good news is that charging batteries will shut off automatically when they’ve reached their safe limit and there’s always a little in reserve even if your phone won’t start. Again: only do this when really necessary, because it does have a negative impact on battery life.

How to calibrate an Android device battery with root access

Even though I’m not convinced that clearing the batterystats.bin file has any meaningful effect on how the Android system reports remaining battery charge, there are those who swear by this method.

So in the interest of fairness, we’ve included the process for you here (it is true that different manufacturers use the batterystats.bin file for different things).

It’s basically the same process as above, but with the added step of using a root-enabled app to make it more reliable. Readers have rightly pointed out in the comments that newer versions of this app ask for a disturbingly extensive list of device permissions. If this worries you, we recommend trying the above non-root method first, and only resort to a 3rd party app if the first method proves unhelpful.