[svlug] question - my laptop won't charge to 100% even though plugged in and using AC power

Brian J. Tarricone bjt23 at cornell.edu
Sun May 3 21:56:39 PDT 2009

On Sun, 03 May 2009 18:47:08 -0700 Alan Denney wrote:

> On Sun, 3 May 2009 17:10:22 -0700, Jeff
> <jeff.lists.nov.2006 at gmail.com> wrote:
> >If you do not use the battery, you practically do no need it. I
> >would remove the battery completely if you do not use it... In your
> >case I would order a new battery and save it for when I travel or
> >other times a battery is needed.
> "Need"?  Maybe not, but it's a darn good thing to have in place  if
> the power goes out in the middle of an unsaved session, even if just
> becomes some idjit kicked the plug out or stepped on the power switch
> for the power strip.

True, but leaving Li ion batteries plugged in all the time is one of
the main things that reduces their life (it's basically the increased
temperature that does it).

> It's probably at least partially salvageable by repeated drawing
> downs and full recharges.

Nope, not in the least.  That may have been true of NiCad and possibly
NiMH batteries, but you'll get the exact opposite out of Li ion
batteries.  Repeated full discharges + full charges are also what
reduces their life.  Li ion batteries don't have the "memory" that
other types do that can sometimes be fixed by "refreshing" them in this
manner.  Doing full discharge/charge cycles will actually make the
battery worse.

Also, they lose capacity just by existing, even if you don't use them.
Assuming you aren't using them, the best thing to do is to store it
around 40% charged in a cold place.  Of course, that often defeats the
purpose of having a laptop :-P

> Best-value source for replacement batteries:  eBay.

Yep, definitely.


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