RE: [Thinkpad] Battery Use

When I was experimenting with "deep cycling my battery, I found the practice
increased the battery's temperature to "hot to the touch" level. This
seemed to severely kill the battery's capacity. Yet IBM's instructions said
to do this three times or so. I chose to do this quickly and lost capacity
(A LOT!) I decided on the next battery to do this over three days with
overnight charging when the battery was cool or cold. It didn't give me
added capacity according to the meter, but the battery seemed to run longer.

My only complaint with the instruction is that IBM needs to emphasize
keeping the battery cool. This was lightly mentioned in the Access Thinkpad
help file (which is what gave me the clue.) I think had they had a big
warning about that fact, it would have prevented me from wasting two
previously good batteries.

I would like to have software control over charging as well. It would be
nice when one deep cycles a battery, that they can leave the battery in
place while not charging. When I decide to have the charging begin I can
click a button. This way the battery can be stored in the machine at a low
charge without keeping it at 100%. This could be done with a scale that you
use to set the level in percent for desired level of charge. So if I want
the battery to be "stored" in my ThinkPad at 40%, I should be able to set it
at that level and the machine will control how much charge to feed to the
battery. If I need it to go to 100% for some reason, I could set it at 100%
the night before I need the capacity. This could have a significant
reduction in battery cycles. One thing nicer would be an additional circuit
that prevents the battery from charging if it's too warm/hot.

George

-----Original Message-----
From: Chris Thomas [mailto:yahoonews@mediumcool.f2s.com]
Sent: Monday, March 08, 2004 5:02 PM
To: Colgrove, George
Subject: RE: [Thinkpad] Battery Use

George,

Interesting thought about charging the battery while the laptop is off.
Perhaps this is what's meant by IBM's garbled advice to charge overnight
following a deep discharge - It always seemed pointless to me as the battery
stops charging once it hits 100%.

I started 'deep cycling' my battery after I'd had the T40 for a couple of
months (and I found the battery meter :-). The first few cycles seemed to
gain some capacity, but after that it's just leaked away. I think though,
that losing capacity is a fact of life - it's just that the meter can only
recalibrate when you do a deep cycle. If you avoid it the battery seems to
survive better, but you've still lost the capacity - you just don't know
about it....

I always try to keep the battery well run down unless I anticipate using
it - a 100% charged Li-ion battery loses 20% of it's capacity in a year....
This is a pain to do as it appears it's not safe to run with the battery
removed - it's a shame you can't control charging from software.

Chris

> -----Original Message-----
> From: thinkpad-bounces@stderr.org [mailto:thinkpad-bounces@stderr.org]On
> Behalf Of Colgrove, George
> Sent: 05 March 2004 13:14
> To: thinkpad@stderr.org
> Subject: [Thinkpad] Battery Use
>
>
> I've discovered some things with ThinkPad batteries as of late. Based on
> requirements from IBM, to "recondition" a battery, I would use the battery
> all the way to "empty". Then I would immediately recharge the
> battery only
> to find that it gave me less time as it did before. It seemed by
> following
> this advice only was killing my batteries. So I stopped doing that and
> resorted to "topping it off every now and again when I did use
> the battery.
> This seemed to do a better job at keeping my battery capacity at an even
> level. The last couple times I did use my battery down to nothing, I took
> the battery out before plugging in the A/C. After the battery
> cooled down,
> I put the battery back in to recharge while the machine was not
> being used.
> This has been keeping the battery capacity at the same level now for quite
> some time! It also seems that I can get the same output of the
> battery more
> consistently. So my advice is the following:
>
>
>
> 1. Use the battery when you need to.
> 2. Top it off after such use - only when the battery is cool and when
> the machine is off. I have charged the battery while using the computer
> when the battery had 93% charge or greater with no effect.
> 3. Charge down the battery once a month as IBM suggests to recondition
> the battery.
> 4. Let the battery cool.
> 5. Recharge the battery when the machine is not being used - overnight.
>
>
>
> I have found that this has been keeping my battery capacity at a constant
> level. If there is something I'm missing, please discuss.
>
>
>
> George
>
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Received on Tue Mar 9 07:47:07 2004