How long laptop battery should live ?

Adam Vande More amvandemore at
Wed Nov 24 05:17:39 UTC 2010

On Tue, Nov 23, 2010 at 10:55 PM, Ian Smith <smithi at> wrote:

>   > I'm guessing if this should be, the laptop has only about 8 months and
>  > I don't use it much on battery, only around one day per week and not
>  > until the battery is empty. If I remember correctly my old laptop
>  > didn't lost so much of capacity in a few months like that.
> Yes 8 (or 15) months is way too soon to lose half its capacity, even if
> you'd been running it on battery for a lot of the time.  This old Compaq
> laptop's battery (Li-ion, 14.4V) is at least 7 years old, and still runs
> for about 1.5 hours, ie 40-50% capacity, and in a subtropical climate.

As already mentioned in a previous link you can't determine a battery's
expected viability by age alone.  The amount and way you've
charged/discharged the battery will factor into it's performance along with
other things.  You should also consult the owners manual as battery
characteristics will vary some.

IIRC, there where some improvement to HEAD while ago that increased FreeBSD
power usage efficiecy a non-negligible amount.  Perhaps those improvements
where MFC'd already, Google around either way as there are settings to tune
which will decrease power consumption.

Adam Vande More

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