[Noisebridge-discuss] lithium-ion battery questions

David Yao kudegra+nb at gmail.com
Sun Dec 20 04:42:24 UTC 2009


I think the sales person was speaking in term of using it in the laptop
until the laptop does its own safe shutdown, which is a safe discharge for
li-ion batteries. The computer ought to follow the norms for protecting the
battery in this case. I presume damage doesnt occur until the battery is
discharged beyond this OS shutdown point. Thus you should be fine if you
start charging soon after OS deems it time to shutdown.

A possible reason for his recommendation to cycle the battery like this is
that the OS/BIOS could need to re-calibrate with the new battery. Going
straight from and old, worn out battery, to a fresh new battery can make the
laptop's time-remaining estimation inaccurate. ie, laptops supposedly
re-calibrate the time-remaining with every charge-discharge cycle, and so
the calibration for an old battery can be vastly different than what it
should be for a new battery. Doing a full charge-discharge cycle a few times
ought to re-calibrate it.

That's my guess.

-
DYao


On Sat, Dec 19, 2009 at 8:28 PM, Michael Shiloh <michaelshiloh1010 at gmail.com
> wrote:

> I little suspicious advice. I think discharging completely is very bad
> for Li batteries, so much so that they usually have a built in circuit
> that cuts out at some threshold.
>
> If no one on this list is an expert, I can forward your question to a
> friend who is quite an expert.
>
> M
>
> John Magolske wrote:
> > I recently bought a replacement lithium-ion battery for my X40
> > ThinkPad. The salesperson at Central Computers mentioned I should
> > charge it to 100% and completely discharge it, cycling twice in this
> > manner as an initial "breaking in" procedure. Would anyone know if
> > this is appropriate for a lithium-ion battery? Battery University [1]
> > recommends against discharging lithium-based batteries too deeply.
> >
> > Also, there are safety issues with lithium-ion batteries [2], so I'm a
> > little concerned that I might be taking more of a risk by purchasing a
> > "no-name" replacement rather than the official Lenova branded battery.
> >
> > [1] http://www.batteryuniversity.com/parttwo-36.htm
> > [2] http://www.batteryuniversity.com/partone-5B.htm
> >
> > TIA for any perspective on this,
> >
> > John
> >
> >
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