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How To Lower the Critical Battery Level to 1% in Windows 7

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With specific hardware configurations, Windows refuses to let you change the Critical Battery Level below a specific point. If you’ve got a big battery, this prevents you from using every last bit of juice. Thankfully, there are two easy workarounds.

We’ve already shown you How To Tweak the Low Battery Action on Your Windows 7 Laptop, but Windows can be stubborn. On my particular laptop, it won’t let me set the critical battery level to anything below 5%; it changes back to 5% as soon as I click something else. On my netbook, that’s close to 20 minutes I’m missing out on, and it takes less than 30 seconds to hibernate so I know I would be fine with 1%. Depending on your specific hardware this number may be different, or you may be lucky and not have this problem at all; it appears that many Macbooks running Windows 7 don’t have this issue. If you’re like me, however, there are two solutions you can choose from: one that’s easy and another that’s slightly more involved.

Pull the Battery

Plug in your laptop so that it’s drawing power from the wall. You can pull the battery on the live system this way without any problems. Once the battery is removed, you should be able to change the critical battery level like normal, only this time your settings won’t change back. When you’re done, just put the battery back in.

power options

This doesn’t appear to work on all systems. If you tried this and it didn’t work, the next solution will.

Use Powercfg.exe

If your laptop doesn’t have a user-replaceable battery, or for whatever reason you can’t remove the battery while the system is on, you’re not out of hope yet. We can set the lower percentage manually using the command-line utility Powercfg.exe, so go to Start > All Programs > Accessories > Command Prompt.

First, we need the GUID of your power scheme. Input the following command:

powercfg.exe –l

That’s an ‘l’ as in “list,” which is what powercfg will do.

powercfg list

Your currently active power plan will be marked with an asterisk. I only ever use the first one, but if you switch power plans, you’ll need to go through this process for each one. Find the one you want to change in the list, right-click, and select “Mark.” Now you can select the long alphanumeric string with your mouse cursor, and then hit the Enter key to copy it. You should paste this in a notepad window, because we’ve got more to copy.

Next, we need the GUID of the subgroup and the setting we’re looking to change. Run the following command and replace “[SCHEME_GUID]” with what you just copied.

powercfg.exe –q [SCHEME_GUID]

You’ll get a low of text in the command prompt. Scroll through it and look for “Critical battery level.” First you need to copy the long alphanumeric string that belongs to the subgroup “Battery,” which you can find a short ways above “Critical battery level.” Paste that in your notepad window. You’ll next need to copy the GUID for the setting, which is right next to “Critical Battery level.” The following screenshot highlights the section to look for in red and the two GUIDs you need to copy in cyan.

powercfg query

Now we have all of the pieces we need to build our command:

powercfg.exe –setdcvalueindex [SCHEME_GUID] [SUBGROUP_GUID] [SETTING_GUID] [VALUE]

Fill in the Scheme, Subgroup, and Setting GUIDS from your notepad window and replace “[VALUE]” with your desired percentage. Hit the Enter key to set it. Here’s the command I used for my particular needs:

powercfg.exe -setdcvalueindex 381b4222-f694-41f0-9685-ff5bb260df2e e73a048d-bf27-4f12-9731-8b2076e8891f 9a66d8d7-4ff7-4ef9-b5a2-5a326ca2a469 1

This will set my critical battery level when on battery power to 1%. If you want to also change the setting for when you’re on AC power as well, just hit the Up key in the command prompt (to bring up your previous command) and change the

-setdcvalueindex

option to:

-setacvalueindex

That’s it! Now you can squeeze every last possible minute out of your battery, whether Windows wants you to or not!

Yatri Trivedi is a monk-like geek. When he's not overdosing on meditation and geek news of all kinds, he's hacking and tweaking something, often while mumbling in 4 or 5 other languages.

  • Published 04/7/11

Comments (12)

  1. WayneW

    I don’t think this is a good idea.
    COMPLETELY draining a battery can and most likely WILL kill cells in the battery.
    You can drain batteries to a very low level and they’ll be fine. It can actually be beneficial, but not COMPLETELY which is possible with such a slim threshold for error. 1% is NOT enough unless you have plenty moola for more power.
    One computer might error on the plus side and the next might kill the battery.
    If battery life is CRITICAL for you, buy a spare and if you need to, start working out if carrying it around just whoops your butt.

  2. Ajith Antony

    Wayne is right, completely discharging is bad. These limits are set like this to protect the battery, and prolong its useful life.

    http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

    From their tests:
    100% Depth of discharge 500 cycles
    50% Depth of Discharge 1500 cycles

  3. xilmiki

    This is not a good idea.
    Completely drain a li-ion battery will damge it!

  4. Nicholas Turner

    Keep in mind everyone that the battery’s in laptops have internal protection circuits.

    You won’t be able to damage the battery by doing this, but you may lower its useful life.

  5. OSD

    Thnx Man This Was What I Wanted :-*

    :)>-

    Thnx A Loooooooooooot

  6. ek

    Thanks, this helps, but I set the level to 5 instead of 1.

  7. Jake

    Thanks for the guide very good and easy to follow. I used it to set the critical battery level to 2% so I can properly calibrate my battery.

  8. hakke

    Wonder if anyone could help.

    Lowered the critical level on my HP dm1 by removing the battery and set the level to 1%. Computer still went to hibernate at 5% despite the level showing 1%.

    Used the more complex way and once again set critical level to 1%. Now the computer hibernates at 7%???

    My settings are for HP recommended, both AC and battery:

    Critical Battery Action: Hibernate
    Low Battery Level: 3%
    Critical Battery Level: 1%
    Low Battery Notification: on
    Low Battery Action: Do nothing
    Reserve Battery Level: 0%

  9. jack

    your thing didnt work..at the command prompt i get “invalid parameters”

  10. rocket7777

    First of all, how computer know how much battery remains? My guess is it very conservatively estimating from voltage and other info.

    Secondly, 0% most likely does not mean 0 voltage. I thing 0% would just mean bottom of useful voltage plus some safety margin.

    I just bought cheap used netbook so I wanted to recondition the batter… but it stayed at 6% for 10-20imin.

    Reading at this thread, it is probably nor worth bothering finding a way to set it below 5%.

  11. E-TARD The LifeCaster

    Thanks for this blog post :D
    the settings would not change on my pc that has an APC.
    I had to use the Command Prompt to get it to change
    but on my laptop settings changed with out having to do anything.
    windows 7 can be kind of odd at times.

  12. Mike

    This allowed me to change my stubborn 98% setting on my Desktop that uses an APC UPS. Only time will tell if it works because out of the blue this seems to happen (forced quick Hibernate).

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