[Thinkpad] TP600 Battery Pack problem

Fri Dec 5 16:09:21 CST 2003

Seems unlikely that they count charge cycles as there are folk who do repack
600 series batteries for a living.  I've been waiting for some downtime to
try repacking the ones I have here.

J.
----- Original Message ----- 
From: "David Gemmell - VK4GL" <david.gemmell at optusnet.com.au>
To: "Steve Carter" <scarter at vcnet.com>; <thinkpad at stderr.org>
Sent: Friday, December 05, 2003 4:14 PM
Subject: Re: [Thinkpad] TP600 Battery Pack problem

> Hi Steve,
>
> That's the most lucid reply I've ever seen on a newsgroup / mail-list.
> That's saved a heap of my time.
> Thank you - you've made my day !
>
> Continuing then ...
> If IBM counts charge cycles, is it then the case that
> replacing single batteries in a used battery pack
> is a total waste of time?
>
> If the the micro-controller has reached it's
> max-recharge-count and shut down further
> charge cycles, putting a new battery (or batteries)
> in the pack will achieve nothing ??
>
> Is this what happens ?
>
> Now that's REALLY planned obsolescence !
>
> And I'll bet there's no way of resetting the counter ?
>
> How Cool !  Next we'll have cars that have a
> max-start-counter and can never be started again ... :-)
>
> Cheers
>
> David
>
> ----- Original Message -----
> From: "Steve Carter" <scarter at vcnet.com>
> To: <thinkpad at stderr.org>
> Sent: 05 December, 2003 5:32 AM
> Subject: Re: [Thinkpad] TP600 Battery Pack problem
>
>
> >
> > The built-in smart charger for the TP600 battery pack
> > appears to be a fairly sophisticated microprocessor-based
> > controller.  You can see the crystal in several of the photos.
> > One of the surface-mount ICs appears to be a micro-controller,
> > and there are a lot of other supporting integrated circuits.
> >
> > The problem they (IBM) are trying to solve is that in any series
> > battery, some cells age faster than others. The hottest ones
> > presumably age more rapidly, as James pointed out.  But they
> > all age, even when not being used -- especially Li-Ion cells.
> >
> > At the end of useful battery life, the cells that have lost the
> > most capacity (i.e. aged the fastest) become overcharged when
> > trying to charge the remaining cells -- they're all in series
> > and the same charge current flows through each cell.
> >
> > But here's the catch:
> >
> > Li-Ion cells can and have explode(d) when overcharged.  It seems that
> > they when overcharged they evolve metallic Lithium, which is hugely
> > reactive, and this results in a spontaneous reaction, or explosion,
> > euphemistically called "venting with flame" by the cell manufacturers.
> >
> > On the NASA's Mars Rovers, which have 8 Lithium-Ion cells in series (!),
> > the design team created eight individual battery-bypass circuits to
> prevent
> > weak cells from being overcharged.  Hopefully this technique will extend
> > the life of the battery packs, since there is no opportunity to replace
> > the cells once launched.  The Maytag repairman doesn't make house-calls
> > to deep space.   :-)
> >
> > It seems unlikely that IBM went to this extreme in the design of their
> > battery pack for the TP600 series.  What the word-of-mouth evidence
> > seems to indicate is that after, perhaps 300, full (~80%) discharges the
> > charging circuit is deliberately disabled to prevent a liability
> situation.
> > IBM is often said to be a company run by lawyers, as you may have heard.
> >
> > None of this helps you with your quest for the schematic, but it would
be
> > a significant task to reverse-engineer the schematic from the hardware,
> > and you would still have to reverse-engineer the firmware (programming)
of
> > the micro-controller.  Having done this, you would then have to figure
out
> > how to re-program the controller for new cells.  In the end, the
solution
> > might be fairly simple, but getting there could be a long journey.
> >
> > There are replacement TP600 batteries available from non-IBM (Taiwanese
?)
> > sources, so someone may have already gone to the trouble to do this.
> > It seems doubtful (not to their economic advantage) that they would
> > consider releasing the results of their work.
> >
> > I don't want to "rain on your parade", but rather just share what info
> > I've gathered.  I hope you find some of this (way too-long) message
> helpful.
> >
> > ++++++++++++++++++++++
> > On  Wed, 03Dec03, James McKenzie wrote, in part:
> > >From: James McKenzie <jjmckenzie51 at sprintpcs.com>
> > >To: David Gemmell - VK4GL <david.gemmell at optusnet.com.au>
> > >
> > >David:
> > >I don't think the problem is with the PCB, but rather with the
placement
> > >of the battery in the Thinkpad.  When I disassembled a 'dead' battery
> > >for the 600 series, I found that the two cells closest to the CPU
> > >(and a great source of heat) were "fouled"  and would not take a
charge.
> > >The other cells in the battery were just fine and continue to take a
> > >charge.  I could rebuild the battery with new cells and I would expect
> > >the 'new' battery would last as long as the 'old' battery.
> > >
> > >However, I don't know of a source for the schematic for the PCB.
> > >Maybe, someone on the list can locate one.   >James McKenzie
> > >
> > >
> > >David Gemmell - VK4GL wrote:
> > >>I had seen that site, some excellent info,
> > >>but I was really after the schematic of the PCB
> > >>in the batt case to see where the design was astray.
> > >>
> > >>----- Original Message -----
> > >>From: "James McKenzie" <jjmckenzie51 at sprintpcs.com>
> > >>
> > >>>There was a lengthy discussion on rebuilding 600 series batteries.
> > >>>Look at the following site as it has instructions on how to rebuild
> > >>>Thinkpad 600 series batteries:
> > >>>
> > >>>http://www3.sympatico.ca/milnoc/TP600Battery/
> > >>>
> > >>>It provides a great wealth of information on the 600-series
> > >>>battery  problems and links on how to rebuild them. >James McKenzie
> > >>>
> > >>>
> > >>>David Gemmell - VK4GL wrote:
> > >>>>After reading many of the postings on TP600 battery pack
> > >>>>problems, I would like to have a go at repairing mine.
> > >>>>
> > >>>>And - please - I do understand all the warnings about this -
> > >>>> (the sky will fall in  - etc etc,)
> > >>>>but I do have the required knowledge and equipment.
> > >>>>
> > >>>>Does anyone have a SCHEMATIC of the charge control
> > >>>>circuitry which is built into the battery pack?
> > >>>>Thanks David
> > >>>>________________________
> >
> >
> >
> >
>
>
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