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First of all, I am not sure the title of this question is the most appropriate however this is what I meant to say,

There are many ways to extend the life of a laptop battery. One way is by not connecting it to the AC adapter all the time which will overcharge it. I read that in this website.

  1. Is there an application which automatically prevents the charging of the battery once it has reached 80% charged? I mean that is such a cool feature. Sometimes people tend to forget to remove the AC adapter and this could diminish the capacity and reduce the life time of the battery.

  2. Does the battery indicator in ubuntu display info or pop-up when the battery is almost dead (dead not in the sense of usage time) but rather a degraded battery?

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I read the opposite from that link. If you keep connecting and disconnecting the battery it will give you less life. Removing it will make you go through more discharge cycles. Check the graphics in your link. What is true is that keeping it at 80% or 50% of the maximum capacity will increase it's live. Note that you can to destroy a battery by letting it get to no charge at all (not where the computer reports 0%, but lower), check the storage instructions on your link. – Javier Rivera Jan 13 '11 at 15:02

5 Answers

up vote 13 down vote accepted

Wow, that web site is COMPLETELY WRONG. I am an engineer and among other things, sometimes design and build battery packs. I have read many data sheets from battery manufacturers and they all say the exact opposite, and I have experimental evidence that they are correct.

Batteries LIKE being fully charged. If the charger is overcharging them, then it is broken. A correct charger stops charging the battery when it is full, so it is good to leave it plugged in if you can. The more often you discharge the battery, and the deeper you do so shorten its life. A typical battery can handle several thousand cycles if you limit depth of discharge to 30% ( meaning you recharge it once it falls to 70% ). Going to 50% cuts the life of a typical battery down to the 1000 cycle range, and 30% or less drops it to a few hundred. A battery that is fully discharged and remains that way for weeks or months will loose much of its capacity if it can be recharged at all.

Notice the inverse relationship between depth of discharge and state of charge. Battery manufacturers and engineers use the former term. The marketing guy who wrote that web site probably did not understand the difference and so he got it upside down.

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Wow thanks so much I never knew this, and was always getting wrong info from HP and others. – RolandiXor♦ Sep 24 '11 at 2:25
great, i practiced full discharging policy and as a result my battery performance has degraded. – Ankit Oct 1 '12 at 13:18
up vote 3 down vote

  • You can get some additional information, apart from right clicking the battery icon next to the clock (get's shown when you pull out your power chord), by opening a Terminal and typing

    cat /proc/acpi/battery/BAT1/*

  • Does the battery indicator in ubuntu display info or pop-up when the battery is almost dead (dead not in the sense of usage time) but rather a degraded battery?

    Yes it does:

    alt text
    (something like that)

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In case anybody's wondering: Yes this is an old screen shot, but I have actually seen this message — it's just hard to replicate. :) – Stefano Palazzo♦ Jan 13 '11 at 23:24
up vote 2 down vote

I don't agree with the answer. Keep battery always 100% charged is NOT suggested.

For Li-Ion rechargeable battery (almost all laptop use li-Ion battery) , most manufacturers suggest to keep them in a cool and dry condition with 40%~50% capacity, no matter for camera battery or laptop battery. Why? Because this is the best conditon for battery storage. I have several evidences to support my opinion:

1) My Thinkpad X31 laptop with battery always full charged and dead in around 3 years later. Only 10% capacity left.

2) My Thinkpad T400 laptop has a battery with good condition after 3 years usage (more than 85% capacity left), by limitting the threshold to 30%~80%. I never overcharge or deep discharge the battery, it will reduce the lifespan of battery significantly.

3) I have several 18650 size Lion Sanyo batteries, which is the material of laptop battery, when they were shipped to me, the voltage are all around 3.78V (around 40% of it's capacity), while the full charged voltage is 4.20V. It means in factory, they are charged only to 40% capacity, for storage reason.

I saved them for around 2.5 years in refrigerator (so it's always cool), and the voltage of them still keeps around 3.76V~3.77V.

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up vote 0 down vote

My netbook computer, as Asus 900, has a battery that I think I overcharged, and it now indicates that it is either at a very low charge level, or broken, which I believe. This is indicated at boot time of Ubuntu. However, I can still use it for a little bit of time before the computer runs out of power.

I now keep my battery disconnected from the computer (a new one) when I use it on the power supply.

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up vote 0 down vote

If you right click on your panel so can you get some choices, there are a number of applications of how much battery there is left

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