ThinkPad battery charging thresholds
There are a lot of theories and information about ThinkPad charging thresholds. Some theories say thresholds are needed to keep the battery healthy, some think they are useless and the battery will work the same just as it is. In this article I will try not to settle that argument. 🙂 Instead I try to tell how and why I use them, and then proceed to show how they can be changed in different versions of Windows, should you still want to change these thresholds.
Update 29.3.2016: I updated the information regarding Windows 10.
Update 1.11.2016: This article is very popular, so I added some more information, mostly to Windows 10.
Update 8.2.2017: Added link to battery information tool article.
Update 16.2.2017: Added information about custom threshold in Windows 10 available again
Why I use them?
I use charging thresholds to lower the percentage when the notebook starts charging, usually to about 60%-70%. I unplug my ThinkPad from AC power for short periods, and then use it again by plugging it in. These interruptions are often short meetings that only drain the battery a little bit, but enough to trigger a charging should I plug it in again (10-20%). By using the charging thresholds, I wanted to prevent the battery from being constantly charged.
Charging all the time – in my experience – ruins the internal meter of the battery quickly, requiring battery gauge resets. So it does not really stress the battery but causes symptoms that then need curing, should you wish to use the notebook to it’s full potential.
By the way, if you need to check on the wear level of your battery, I have created a small utility that can be used to see how your battery is doing. Read more about it and download it from these pages.
My preferred settings
My preferred settings are starting charging when the charge goes below 60% and fully charging the notebook.
The reasons for choosing these settings is that 60% is still acceptable should I choose to use my notebook away from power. And it allows for 2-3 of my short meetings without the notebook charging back up again. But below that I want it charge up, so I am ready to be away from the power adapter.
Charging thresholds in Windows 7
On Windows 7 you use the ThinkPad Power Manager software to set the charging thresholds. You can set when to start charging and when to stop charging. The defaults are: start when under 96% and stop when the battery is full.
To access charging thresholds, you need to switch Power Manager into advanced mode. Then you access the charging thresholds from the battery options.
Charging thresholds in Windows 8/8.1
On Windows 8 and 8.1 the Power Manager is not officially supported. Using some compatibility mode trickery you can make it work, but it will not be able to set the charging thresholds. Instead, you need to set them in the registry yourself. These will get written to the battery on next reboot.
For 64 bit systems, the registry key you are looking for is:
Under this key there are several values:
For the ChargeStartControl and ChargeStopControl values set them to 1.
For the ChargeStartPercentage, specify the percentage of charge after you want charging to start. This is the value you would set to 60 if you want charging to begin when the charge goes below 60%.
For the ChargeStopPercentage set the percentage you want charging to stop at. This could be 100 if you want the battery fully charged, or something lower if you do not want to charge the battery all the way.
Set everything to 0 to restore defaults.
Changing these values with not take effect right away: you need to reboot your system, and these values are then written to the battery at reboot.
However, reinstalling / updating the Settings Dependency Package will reset these settings. You will then have to specify the values again, and then reboot again for the settings to be applied again. Not at all an ideal situation.
Charging thresholds in Windows 10
The old Power Manager software is not available in Windows 10. I was not able to run it, even with the tricks that worked in Windows 8.
The Lenovo Settings application that you install from the Windows Store has now a fully configurable charge threshold section. If you want to use it, you will need both this program and another set of helper programs (Dependency Package or similar name). The Lenovo Settings app you can get from the Windows Store, and it should prompt you to download the other needed component when you run it for the first time.
While previously this was not fully featured (before february 2017), now you can set it up the way you like. So no more need to fiddle around the registry to have fully custom settings.
Manual setting for starting percentage
If you do not want to use Lenovo Settings, you can still enter the settings manually. It is similar to the registry method that I described above, but involves changing different keys. The method was first published on Lenovo Forums.
Instead of the registry key I gave above, look for a key here:
Here the batteryserial is the serial code for your battery. You can find it in the Lenovo Settings app, by opening the battery page and looking at Power Status. Click on the Show Details button, and in a moment it will refresh the settings and tell your the Bar-Code number of the battery. This is the key you need to look up in the registry. You can find it without it, because it is a mix of letters and numbers, and stands out from the sane sounding other keys 🙂
The four values are the same as before, and you should set them in the same way. They might be missing, in which case you need to create them. If you are missing the entire key (batteryserial), you will need to install Lenovo Settings to have it create the appropriate keys.
Just remember that if you open Lenovo Settings or update the dependency package, it will reset the settings right away. The only way to restore them is to enter them again, and reboot.
I verified this with the ThinkPad X1 Yoga, and it works. It’s a little slow because you need to reboot for the new values to take effect, but it works.
What if I upgraded my old Windows installation to Windows 10 and I have previous thresholds set? Am I stuck?
If you install Windows 10 while you have set charging thresholds, they will still be in effect after the upgrade.
You can either install Lenovo Settings app (described above), and use that to reset the settings.
Or you can use the above registry method to set up the thresholds once again.
If you want to reset your thresholds without using the registry or the app, turn off your ThinkPad and disconnect your battery for a few minutes. Then reconnect and start charging. This should reset the charging thresholds.
This is a problem with integrated batteries – for these systems disconnecting the battery using the BIOS might do the trick. I have not verified this, however.