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How to Calibrate Your Laptop’s Battery For Accurate Battery Life Estimates

laptop-battery

So you’re using your laptop and, all of the sudden, it dies. There was no battery warning from Windows — in fact, you recently checked and Windows said you had 30% battery power left. What’s going on?

Even if you treat your laptop’s battery properly, its capacity will decrease over time. Its built-in power meter estimates how much juice available and how much time on battery you have left — but it can sometimes give you incorrect estimates.

Why Calibrating the Battery Is Necessary

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If you’re taking proper care of your laptop’s battery, you should be allowing it to discharge somewhat before plugging it back in and topping it off. You shouldn’t be allowing your laptop’s battery to die completely or even get extremely low each time you use it. Performing regular top-up will extend your battery’s life.

However, this sort of behavior can confuse the laptop’s battery meter. No matter how well you take care of the battery, its capacity will still decrease as a result of unavoidable factors like typical usage, age, and heat. If the battery isn’t allowed to run from 100% down to 0% occasionally, the battery’s power meter won’t know how much juice is actually in the battery.

windows-battery-meter

How Often Should You Calibrate the Battery?

Manufacturers generally recommend calibrating the battery every 2-3 months. This helps keep your battery readings accurate.

In reality, you likely don’t have to do this that often if you’re not too worried about your laptop’s battery readings being completely precise. However, if you don’t calibrate your battery regularly, you may eventually find your laptop suddenly dying on you when you’re using it — without any prior warnings. When this happens, it’s definitely time to calibrate the battery.

Basic Calibration Instructions

Calibrating — or recalibrating, really, as the battery was calibrated in the past when the battery had more capacity — involves letting the battery run from 100% capacity straight down to almost dead, then charging it back to full. The battery’s power meter will then see how long the battery lasts and get a much more accurate idea of how much capacity the battery has left.

Some laptop manufacturers include utilities that will calibrate the battery for you. These tools will usually just make sure your laptop has a full battery, disable power management settings, and allow the battery to run to empty so the battery’s internal circuitry can get an idea of how long the battery lasts. Check your laptop manufacturer’s website for information on using any utilities they provide.

You should also look at your laptop’s manual or help files. Each manufacturer may recommend a slightly different calibration procedure or tool to ensure your laptop’s battery is properly calibrated. Some manufacturers may even recommend against doing this. Apple says its newer laptops don’t require this calibration procedure, although older models do.

msi-battery-calibration

How to Manually Calibrate a Battery

While it’s a good idea to use any included utilities or just follow instructions specific to your laptop, you can also perform battery calibration without any specialized tools. The basic process is simple:

  • Charge your laptop’s battery to full — that’s 100%.
  • Let the battery rest for at least two hours, leaving the computer plugged in. This will ensure that the battery is cool and not still hot from the charging process. You’re free to use your computer normally while it’s plugged in.
  • Go into your computer’s power management settings and set it to automatically sleep or hibernate at 5% battery.

hibernate-at-low-battery

  • Pull the power plug and leave your computer discharging until it automatically sleeps or hibernates. You can keep using your computer normally while this happens.

(Note: If you want to calibrate the battery while you aren’t using the computer, be sure your computer isn’t set to automatically sleep, hibernate, or turn its display off while idle. If your computer automatically enters power-saving mode while you’re away, it will save power and won’t discharge properly.)

disable-sleep-and-display-power-off

  • Allow your computer to sit for five hours or so after it automatically shuts down.
  • Plug your computer back into the outlet and charge it back up to 100%. You can keep using your computer normally.
  • Ensure any power management settings are set to their normal values. For example, you probably want your computer to automatically power off the display and then go to sleep when you’re not using it to save battery power.

power-plan-settings

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Your laptop should now be reporting a more accurate amount of battery life, sparing you any surprise shutdowns and giving you a better idea of how much battery power you have at any given time. The key to calibration is allowing the battery to run from 100% to almost empty and then charging it all the way up to 100% again, which may not happen in normal use.

Image Credit: Intel Free Press on Flickr

Chris Hoffman is a technology writer and all-around computer geek. He's as at home using the Linux terminal as he is digging into the Windows registry. Connect with him on Google+.

  • Published 09/16/13

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