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

Chris Miller lordsauronthegreat at gmail.com
Mon May 4 01:47:25 PDT 2009


On Mon, May 4, 2009 at 1:23 AM, Brian J. Tarricone <bjt23 at cornell.edu> wrote:
> On Sun, 3 May 2009 22:52:03 -0700 Chris Miller wrote:
>> On Sun, May 3, 2009 at 9:56 PM, Brian J. Tarricone
>> > 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.
>>
>> I'd love to believe you, but personal experience with Li Ion batteries
>> would suggest otherwise... Unless I'm getting stiffed and they're
>> giving me NiCad while telling me it's Li Ion.
>
> Then your personal experience must be a bit flawed ^_~.  Go and do some
> reading on this.  Li-ion batteries have a limited number of charge

I have.  And that reading isn't entirely in line with what my results
have been in the past.  My current MacBook's battery is behaving much
more like what you describe a Li Ion battery should be behaving like,
whereas the X40 behaved a lot more like a NiCad battery.  Well, it was
five years ago now... so something has changed.

> cycles.  Every time you fully discharge and recharge the battery, you
> "use one up."  Fortunately only a full discharge/charge is considered a
> full charge cycle, so, for example, draining the battery from 100% to
> 50%, charging it back up to 100%, and then repeating that, will only
> "count" as one charge cycle.
>
>> My old X40 actually had a battery "reconditioning" tool which would
>> drain and recharge the battery (while it was still plugged in!) and
>> I'm really certain that it used Li Ion batteries...
>
> Mostly snake-oil.  Occasionally the circuit in the battery that keeps
> track of the high and low charge water marks can get a little
> confused.  "Reconditioning" in this case merely attempts to jog its
> memory a bit.  You're only likely to get into this situation if you do
> a lot of shallow discharge/recharge cycles, so most of the time you're
> probably only reducing your battery's life (ever so slightly) by
> performing this reconditioning.

Leaves me to wonder why LiFe batteries aren't more prevalent...

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