Originally published at: http://www.howtogeek.com/172271/how-to-calibrate-your-laptops-battery-for-accurate-battery-life-estimates/
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?
And for that, I thank you. My laptop's been shutting off at 20% and giving me low battery notifications at 30% rather than 15%.
Won't it be much better if you set the critical/low battery percentage to 0%? You can do that from the command line with powercfg.exe
No. It would be much better to recalibrate the battery and allow the computer to autoshutdown at the factory percentage. If the battery goes to zero before shutdown is completed, the OS could get scrambled.
I think you don't understand me If you set the battery's critical level action to sleep and set the critical level percentage at 5%, the battery will make the computer go to sleep when the battery is supposed to be at 5%. The entire point of calibration is to find out how much more/less juice the battery actually contains compared to what it's telling the computer, so you have accurate readings.
And also, what do you mean by "the OS could get scrambled"?
Ever seen a scrambled egg? Take that in one plate, and a boiled egg in another. See the difference.
So...do you regularly boil and fry your computers on the stove? And how is that example exactly supposed to show what happens to a computer when you supposedly remove power to it before it shuts down?
No, my laptop gets so hot, it is my stove
A Windows update could be interrupted. You could have been installing a system level program at the time. Many things.
Well, I'm assuming that if somebody WERE to be thinking of doing a calibration, they would shut down all programs, save their work, etc. Not foolproof, but more than likely not to cause any problems.
But I mean, really? I think that there is less chance of your computer doing a system-critical update or whatever while you're doing a calibration than when you're just plugged into the wall socket and the electricity stops for a second
True, it's not likely but it still can happen (been there and didn't even get the tee shirt). Why take chances when there is no real benefit?
I'm just saying, I suppose that having the computer shut down at 0% rather than 5% will provide a much better calibration result. That's all
It kills me that people still believe this.
Discharging a battery to 0% will use up a charge cycle. Modern lithium-ion and lithium polymer batteries do not suffer from memory problems the way that older nickle-based technology did. Instead, modern batteries are much like modern "smart" inkjet printer cartridges - there's an onboard EEPROM that monitors the number of charge cycles on the battery. Any time the battery goes to 0% and is recharged, that's a charge cycle. There's a set number of charge cycles allowed on a battery (similar to how there's a set number of uses on an inkjet cartridge, and the cartridge notifies the printer when its ROM says it's all used up). OEM battery utilities from HP, Apple, and others simply look at the number of charge cycles on the battery.
Once the battery's charge cycles have maxed out, the battery doesn't work anymore - it will tell the OS it's consumed, and prevent the computer from charging it. This is a safety mechanism to prevent batteries from expanding, exploding, and/or catching fire.
By "calibrating" a lithium-based battery, you're effectively shortening its lifespan. If you do it frequently enough, you'll ruin the battery.
Ok here's a question: My laptop is like the screenshot in the beginning of the article (Plugged in and not charging) and its slowly declined all the way down to 17 %. It used to be able to run off of the battery all the way down to minimal, then it started shutting of at 67%. How can I calibrate it if it can't charge anymore?
OK... so my laptop dies when my battery is at 70%, so setting my laptop to hibernate at 5% or 10% does nothing, because the battery indicator never gets that low.... if I want my laptop to hibernate, I need to set it to hibernate at 75%. I know its just a calibration issue, because my battery still lasts about 2.5 hours, which isn't bad for a Lenovo T430S that's a little over 2 years old and my display is fairly bright, as I can't stand dim displays..
So how can I recalibrate my battery to allow it to go down to 0% again. Lenovo's power management calibration tool failed to do the trick, as the laptop just shuts off at around 70%, which kills the process, because when I plug in the power and reboot, the calibration tool is no longer running. Any suggestions would be greatly appreciated.
On my HP Pavilion 15 with Windows 8.1, Windows doesn't allow me to set critical battery level below 9%. I tried to circumvent it using powerconfig but it was quite complicated. So, I gave up. Will the calibration work at 9% or should I try to get it to 5%?
Never mind. I removed the battery and hence was able to set critical battery level to 5%. Quite easy, actually.