View Full Version : [ubuntu] Voltage History. Should I Be Concerned?

September 18th, 2008, 04:37 AM
Hey all.

Right I have two concerns that I wondered if any of you could possibly aid me with.

First one being:

Basically I first noticed this feature when buggering about with the battery charge option today. I came across a voltage History chart within it while on my Laptop and noticed that the voltage history is as follows:

http://img524.imageshack.us/img524/7033/voltageql4.th.png (http://img524.imageshack.us/my.php?image=voltageql4.png)

Should I be concerned that it's fluctuating? And are those voltage fluctuations reasonable / not harmful?

Second one being:

Booted my laptop up today for the first time in almost a week and the screen was extremely dark. I was a little confused as to why but then I realized it might have just been a brightness setting. I pressed the FN on key and pressed the brightness key and to my amazement it was that the brightness was on as low as it could possibly be. However I never changed it in the first place from 100% to 10% and I couldn't understand why it had dimmed on it's own accord when it hasn't been switched on in a week since my last use of it.

Any ideas?

Thank you for reading the post and I eagerly await any response.

Best regards.


September 18th, 2008, 04:42 AM
I wouldn't worry about those voltage fluctuations, its only .3V at the most, which is reasonable for a battery.

No idea on the screen, although I wouldn't be surprised it maybe it thought it was on battery at some point for some reason and dimmed the screen.

September 18th, 2008, 04:54 AM
Thank you for the response.

At what voltage difference do you think I should start showing concern. Because it seems to have climbed from the first boot up reading of 15.3v to 15.7v in the space of half an hour. Would the voltages differenciate depending upon the usage of the laptop at all? Meaning, the more I do the more voltage it requires? Or am I completely way off base?

Well when I booted the laptop up for the first time in almost a week only moments a go the battery did read less than 8% charge within it so I thought the same as you, I've just never noticed it do this before because I normally use it quite regularly.

If this is the case though and anyone knows where this option is to turn it off, could you possibly point me towards it please? I've gone through the power options via right clicking the battery charge icon and then going to preferences which does have a dim effect feature in there that I switched off. But I switched that off while the screen was dimmed and it had no effect on brightening it up automatically, I still had to do it manually even after having switched it off in the preferences. Is that normal do you think?

This is my first actual notebook (normally I run towers) so excuse the questions being extremely beginnerish.

Best regards,


September 18th, 2008, 05:01 AM
Your battery voltage is a measure of how fully charged the battery is. In fact, the battery gauge reads the battery voltage to calculate how full a battery is, so some fluctuation is normal.

Yeah it seem like maybe it was left on or left in sleep mode and discharged.

Not sure what to tell you about your screen brightness.

If you'd like to read up more on laptop batterys, check out the articles about lithium ion batteries here: http://www.batteryuniversity.com/ . They have lots of great information that will help you know how to keep your battery in good shape and last a long time. These batteries do not behave like rechargeable batteries of old and definitly need different care to work right.