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How to calibrate your laptop’s battery and fix inaccurate wear info

By Douglas Black , last updated on July 27, 2018

The issue I’ve been coming across recently seems to be mostly with Dell’s XPS line of laptops, though it can certainly affect others: My new XPS 13 9370, XPS 15 9575, and XPS 15 9570 showed 8, 14.5, and 10% battery wear out-of-the-box, respectively (a battery wear of 10% means that the battery is only able to charge to about 90% of its rated capacity).

Normally, batteries will only show this much wear after a year of heavy usage, and it isn’t something you should accept in a new laptop. I realized something was up when every single XPS 15 I checked out new had around 10% battery wear reported, however.

Battery calibration hasn’t been much of a necessity since lithium-ion batteries got so much smarter over the past few years. Thus, even as someone who considers themselves to know quite a bit about notebooks, properly calibrating the battery in my new XPS laptops (showing incorrect wear percentages out of the box) was something I had to do a bit of reading up on combined with some trial and error to get right, and so I thought I would write a brief guide on how to do it right the first time.

Following this protocol, I was able to reduce the reported wear levels significantly to the low single-digits and recover a good deal of battery life.

Checking your battery’s reported wear

Before bothering with a calibration, it’s necessary to check the reported health of your battery. If your battery is new and showing less than 95% of its original capacity then it is probably worth recalibrating.

Go to the Start menu and search “cmd” to show the Command Prompt (PowerShell will do fine as well). Right-click the search result to run your choice of app as an administrator. Copy and paste the following line into the command line: powercfg /batteryreport

The battery health report will be output to the Windows\system32 folder by default.

Copy the directory path and paste it into your favourite web browser to view it. Once it opens, you can scroll down a bit and you should see your battery’s health as a function of design capacity (rated capacity) and full charge capacity (actual amount the battery reports it is able to hold).

After calibration. Before calibration, the full charge capacity was only 87,000 mWh, or less than 90% of advertised.

By doing some quick math you should be able to see how healthy your battery currently is. Technically it is not good to fully charge and discharge a Li-Ion battery often (which is what calibration requires), so if your battery is not new and the wear percentage seems reasonable, it may be best to leave it. If you see only 90% of capacity on a new laptop, however, then this guide will definitely help.

The procedure

Step 1:

First, you will need to let your laptop charge to its “full” capacity. OEMs like Dell and Lenovo allow the user to set charging-thresholds on the battery in order to preserve the battery health (this is a very good practice that I encourage all OEMs to follow). Thus, to charge the laptop fully, you’ll need to find that setting and set your charging threshold temporarily to 100%. On XPS machines, this is done through Dell Power Manager or the BIOS.

You’ll need to set the charging behavior to “Standard” or change the slider manually to 100% to complete the first step. Once this is done, make sure your laptop is plugged-in and allow it to charge completely.

Step 2:

Next, you need to let the battery completely discharge until forced shut-off (not just hibernation). There are a few ways to do this, but my favourite method is the simplest: Restart the laptop in BIOS mode, then go out of the house for the day. With this method, you don’t need to worry about the laptop going to sleep or hibernating as these features are not enabled when viewing the BIOS. Additionally, power-saving states are not enabled for the CPU when in the BIOS either, meaning the laptop will run down significantly faster than it would in Windows under normal usage.

You could also use the laptop normally and let it run down until it automatically hibernates, then leave it in BIOS as described above as well. This requires your turn off all of the sleep and hibernation timers in the Power Options control panel first, however.

Step 3:

WAIT. Do not immediately charge the laptop; be sure the laptop has been sitting cool and unplugged for 3-5 hours before the next step. Failing to perform this step can result in making your reported battery wear worse.

Step 4:

Plug the laptop in and let it charge to maximum uninterrupted. You should be able to use the laptop in Windows at this point, but I let it charge in BIOS out of superstition. When you generate your battery report again, you should (hopefully) see a much higher rated capacity for your new battery.

Conclusion

That’s it! Using this method I was able to reduce my 9575 reporting 14% wear down to 4%, my 9570 reporting 10% down to 3.8%, and my 9370 reporting 8% wear down to 4%, and I hope it fixes the problem for you simply as well. As always, try to practice good battery care to prolong their lives: Keep them cool, don’t run them dry, and don’t charge them to maximum often. If you are interested in reading more about safety and care for Li-Ion batteries, you can check out this guide for further reading.

Did you also get an XPS laptop with double-digit battery wear? Please share your results in the comments.

 

 

Based in Hong Kong, Douglas Black is a veteran editor of Notebookcheck, university lecturer, researcher, and writer.

4 Comments

  1. imin

    July 18, 2018 at 11:46 am

    Nice article! But shouldn't Dell at least have a better QC prior to releasing their laptop?

    • Douglas Black

      July 18, 2018 at 11:48 am

      Absolutely — the lack of QC is, imo, one of the main reasons why companies like Apple can exist despite being noncompetitive in almost every other arena. I would guess that whoever has been supplying their batteries is the same company for all 3 XPS machines, thus why they all have incorrect wear/capacities.

  2. Matthias

    August 8, 2018 at 12:12 pm

    worked for me perfectly on my new xps 9570. from 87 to 93mWh.

    If i repeat this process, will i get to 97mWh at some point or is 93 the best result i can get for my battery and it will only get worse from this point?

    • Andrei Girbea

      August 10, 2018 at 2:11 pm

      As far as I know, it shouldn't get worse, so you could try it again, but it won't probably do much. 93/97 is not bad though

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