Take the 2-minute tour ×
Ask Ubuntu is a question and answer site for Ubuntu users and developers. It's 100% free, no registration required.

If my battery is 100% I only have 30mins left. This are my stats:

Energy : 17,6Wh 
Energy when empty : 0,0Wh 
Energy when full : 19,3Wh
Energy design : 48,8Wh 
Rate: 34,6W
Voltage: 11,0V
Time to empty 30,5minutes
Percentage : 91,4%
Capacity : 39,5%

My question is : Does the stats above really say that my battery just has 40% of what it should be after it leave the factory?

share|improve this question
    
The time to empty is calculated with your current power usage, so maybe if you're running many applications it's normal. It depends on many factors such as: how old your battery is, how much it's been charged and emptied, etc. But it is possible, however..it's unlikely if your battery is relatively new (less than 2 years old). –  Oyibo Jul 19 '12 at 19:48
1  
I have read that with LiON batteries in computers or other smart devices, it's a good idea to occasionally let the battery run down to the point where the OS detects the low battery condition, and turns off the computer. This has nothing to do with memory effect like NiCAD batteries, but is a training exercise for the computer to learn how long the battery will last. The computer is smart enough to turn off before the battery is totally dead, a condition that is not good for LiON cells. –  Marty Fried Jul 19 '12 at 21:00
    
@Marty Fried This isn't entirely true. Running down LiIons has no positive effect. There are three killers for LiIon batteries: Heat, Full-charge state, and time. Count on forever losing about 20% capacity per year if stored at a full charge state. Storing between 40-60% charge state reduces that loss. And storing at lower temperatures also helps. But guess what? You're using it on a laptop; almost always kept topped off by its charger, and a good portion of the time generating heat that is gradually cooking the battery. A couple of years and it's well-done (give or take a year). –  DavidO Aug 12 '12 at 4:53
    
Most all of what you say is true, to the best of my knowledge, and I'm aware of all of it. However, as I said, running it down occasionally is not something that is good (or bad) for the battery itself, it's an exercise for the OS so it can better predict the run time. The OS will not allow the battery to fully discharge before shutting down, so it doesn't actually harm the battery. Running it down completely, on the other hand, will harm it. –  Marty Fried Aug 13 '12 at 5:16
add comment

1 Answer 1

That is indeed what it says. It may not be correct though. You might try recalibrating the battery by charging it to full, then discharging it to around 3%, then recharging it. Also, at 34.6 watts, you seem to be consuming a lot of power so you might investigate why that is. powertop may be helpful for that.

share|improve this answer
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.