14 Nov
2002
14 Nov
'02
8:08 p.m.
This has come up before but I can't remember it being resolved.
I often see suggestions for rejuvenating failed or dying laptop batteries using
a hi-amp source to flash them and break down the built-up crystals.
Most mention breaking the pack apart before doing this individually on each
cell. Is this because each cell might have different resistances ? Most of my
LT batteries no longer work anyway so it would be no big loss if it totalled
them. Sending a dozen or so batteries into a rebuild place is a costeffective
non-option and replacing the individual cells would still be costly.
Lawrence
lgwalker(a)mts.net
bigwalk_ca(a)yahoo.com
15 Nov
15 Nov
3:08 a.m.
Lawrence Walker wrote:
This has come up before but I can't remember it being resolved.
I often see suggestions for rejuvenating failed or dying laptop batteries using
a hi-amp source to flash them and break down the built-up crystals.
What really happens is that minute 'hairs' grow from terminal to
terminal in the cell, effectively shorting it out. To remove them
requires a flash of current to 'burn' them out. Either a high current
source (10A or more) or a large capacitor discharged into the cell does
the job.
Most mention breaking the pack apart before doing this
individually on each
cell. Is this because each cell might have different resistances ?
No, each cell has to be individually zapped if shorted. If the cell
isn't shorted, you don't zap it.
Most of my LT batteries no longer work anyway so it
would be no big loss if it totalled
them. Sending a dozen or so batteries into a rebuild place is a costeffective
non-option and replacing the individual cells would still be costly.
My experience has shown me that doing this only extends life for a very
short time, maybe a few months at best, when the symptoms return. By
then the battery pack has pretty much run its lifespan. If your nicad
pack has standard AA/C/D cells, rebuilding is a way around it, but most
packs now have odd-sized cells, so the cost skyrockets there.
If it were my laptop, I'd just spend the money for a new battery.
Gary Hildebrand
St. Joseph, MO
3:24 a.m.
At 09:05 AM 11/15/02 -0600, Gary wrote:
Lawrence Walker wrote:
I have used an automobile battery to "zap" them. Shorting a NiCad to an auto
battery for just a split second usually burns out the whiskers. HOEVER the fix usually
doesn't last long. One of things that happens when the whiskers grow and short the
electrodes is that they also pucture the membrane that separates the electrodes. Once that
happens, the battery doesn't last long. ALSO zapping NiCads can can over-pressure and
rupture the vent and possible spray out electrolyte (potassium hydroxide solution) if get
them too hot. Not only is this an immediate hazard but it can also cause slow leaks that
go unnoticed until the electrolyte eats up the circuits in the device that the batteries
are installed in.
I'm not saying not to zap your batteries. Zapping them is a great way to get them
working again FOR A SHORT TERM. That will at least let you test the device to see if it
works before investing money in new batteries. However just be aware of the dangers of
zapping and DON'T leave the batteries in the device after you're done testing it.
Joe
This has come up before but I can't remember it being resolved.
I often see suggestions for rejuvenating failed or dying laptop batteries using
a hi-amp source to flash them and break down the built-up crystals.
What really happens is that minute 'hairs' grow from terminal to
terminal in the cell, effectively shorting it out. To remove them
requires a flash of current to 'burn' them out. Either a high current
source (10A or more) or a large capacitor discharged into the cell does
the job. 
1:35 p.m.
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4 p.m.
I'm lucky enough to have picked up an old marine battery charger for $5 at a
yard sale last year. It's good for 6v-60v. with voltage and amperage controls
as well as a 10A limiter switch. As I say, I've got about a dozen Ni-Cads and
about a dozen laptops, none of which, except an old NEC, which has a
working battery. Also a Commodore 386 that I've been unable to find a power
supply for,( has a strange 5pin mini-din plug, made by Sanyo I believe
also labelled as a Zeus, and Everex). I have to decide which laps I want to
use as carry-abouts and possibly rebuild them myself as even the rebuilders
charge about US$60 ($6000 Canadian ? :^} ) And if I have to take them apart
anyways I may as well get my own replacement cells and use duct-tape.
Thanks all. There's also a PD program called "deepdran.exe" (deepdrain)
which I can use to exercise the batteries after, if it's successfull. Worth a try.
Lawrence
Rather you than me! A car battery can provide a rediculously high current
(at least 500A), and the risk of the NiCd exploding is pretty high as a
result. I prefer to use a current limited bench PSU (10A max), and even
then to just 'tap' the contact.
lgwalker(a)mts.net
bigwalk_ca(a)yahoo.com
What really happens is that minute 'hairs' grow from terminal to
terminal in the cell, effectively shorting it out. To remove them
requires a flash of current to 'burn' them out. Either a high current
source (10A or more) or a large capacitor discharged into the cell does
the job.
I have used an automobile battery to "zap" them. Shorting a NiCad to an auto battery for just a split second
usually burns out the
whiskers. HOEVER the fix usually doesn't last long. One of things that
Agreed. As you seid below, the NiCds will work long enough to prove that
the rest of the device is working and that it's worth investing in a new
set of NiCd cells.
-tony
16 Nov
16 Nov
10:56 a.m.
On this subject, anyone know what needs to be done with non-nicad laptop
batteries? I have a DEC HiNote ultra II with a bad Li-Ion battery pack that
I'd like to rejuvenate, but I have no idea how to do so and I suspect that the
same zapping technique as recommended for nicads won't do the trick...
Joe said:
At 09:05 AM 11/15/02 -0600, Gary wrote:
- Dan Wright
(dtwright(a)uiuc.edu)
(http://www.uiuc.edu/~dtwright)
-] ------------------------------ [-] -------------------------------- [-
``Weave a circle round him thrice, / And close your eyes with holy dread,
For he on honeydew hath fed, / and drunk the milk of Paradise.''
Samuel Taylor Coleridge, Kubla Khan
Lawrence Walker wrote:
I have used an automobile battery to "zap" them. Shorting a NiCad to an auto
battery for just a split second usually burns out the whiskers. HOEVER the fix usually
doesn't last long. One of things that happens when the whiskers grow and short the
electrodes is that they also pucture the membrane that separates the electrodes. Once that
happens, the battery doesn't last long. ALSO zapping NiCads can can over-pressure and
rupture the vent and possible spray out electrolyte (potassium hydroxide solution) if get
them too hot. Not only is this an immediate hazard but it can also cause slow leaks that
go unnoticed until the electrolyte eats up the circuits in the device that the batteries
are installed in.
I'm not saying not to zap your batteries. Zapping them is a great way to get them
working again FOR A SHORT TERM. That will at least let you test the device to see if it
works before investing money in new batteries. However just be aware of the dangers of
zapping and DON'T leave the batteries in the device after you're done testing it.
Joe
This has come up before but I can't remember it being resolved.
I often see suggestions for rejuvenating failed or dying laptop batteries using
a hi-amp source to flash them and break down the built-up crystals.
What really happens is that minute 'hairs' grow from terminal to
terminal in the cell, effectively shorting it out. To remove them
requires a flash of current to 'burn' them out. Either a high current
source (10A or more) or a large capacitor discharged into the cell does
the job. 
17 Nov
17 Nov
3:57 a.m.
At 03:57 PM 11/16/02 -0600, you wrote:
On this subject, anyone know what needs to be done with
non-nicad laptop
batteries? I have a DEC HiNote ultra II with a bad Li-Ion battery pack that
I'd like to rejuvenate, but I have no idea how to do so and I suspect that
the
same zapping technique as recommended for nicads
won't do the trick...
Don't try to rejuvenate or zap Li-ion packs; they will probably explode.
Plus, the chemistry is such that if you recharge it above
100%, there will be formation of unstable (explosive) compounds.
Li-ion batteries require an intelligent recharger to avoid this.
carlos.
--------------------------------------------------------------
Carlos E. Murillo-Sanchez carlos_murillo(a)nospammers.ieee.org
5:27 a.m.
Good point!
Just for reference, a standard 18650-series Li-Ion cell has about the
same explosive potential as 4 to 5 grams of
gasoline.
Never screw around with raw Li-Ion cells.
Carlos Murillo wrote:
At 03:57 PM 11/16/02 -0600, you wrote:
On this subject, anyone know what needs to be done
with non-nicad laptop
batteries? I have a DEC HiNote ultra II with a bad Li-Ion battery pack that
I'd like to rejuvenate, but I have no idea how to do so and I suspect that
the
same zapping technique as recommended for nicads
won't do the trick...
Don't try to rejuvenate or zap Li-ion packs; they will probably explode.
Plus, the chemistry is such that if you recharge it above
100%, there will be formation of unstable (explosive) compounds.
Li-ion batteries require an intelligent recharger to avoid this.
carlos.
--------------------------------------------------------------
Carlos E. Murillo-Sanchez carlos_murillo(a)nospammers.ieee.org
15 Nov
15 Nov
10:13 a.m.
What's a LT battery ?
Sipke de Wal
-------------------------------------
http://xgistor.ath.cx
-------------------------------------
----- Original Message -----
From: "Lawrence Walker" <lgwalker(a)mts.net>
To: <cctalk(a)classiccmp.org>
Sent: Friday, November 15, 2002 8:12 AM
Subject: Zapping Laptop batteries
This has come up before but I can't remember it
being resolved.
I often see suggestions for rejuvenating failed or dying laptop batteries
using
a hi-amp source to flash them and break down the
built-up crystals.
Most mention breaking the pack apart before doing this individually on each
cell. Is this because each cell might have different resistances ? Most of my
LT batteries no longer work anyway so it would be no big loss if it totalled
them. Sending a dozen or so batteries into a rebuild place is a costeffective
non-option and replacing the individual cells would still be costly.
Lawrence
lgwalker(a)mts.net
bigwalk_ca(a)yahoo.com
11:16 a.m.
Andy Holt wrote:
I seem to remember a huge battery with a four-pin-socket, that you got
HT with your LT, and the HT was 90V. Half the weight of a good old fashioned
radio seemed to be made up of the battery, and it always seemed a very long
way
home from the jumble sale (I believe that the over-the-ponders call these
'rummage sales'). At the age of 9 or 10, the sheer size and weight of the
radios
meant that you always did something with them after you had fought them
into the house...
Cheers,
Dave.
What's a
LT battery ?
To me (and, I expect, to Tony) it powers the heaters in a valve (tube to
those across the herring pond) portable radio :-) An almost obsolete term.
In the message you were looking at, it appears to be LapTop (normally a
Nicad)
Andy 
1:35 p.m.
HT stands for High Tension and LT for Low Tension (filaments). I have been
zapping NiCds for about 40 years and have a fairly decent success rate. If
it is not going to work you will know real soon. Sometimes a battery just
cannot be zapped at all, in other words regardless of the finite high
current that you momentarily put through it, it will still be a short. No
sense wasting time on those. Others will open up and even take a charge
during the zapping process. As mentioned before they need to be zapped
individually. Just about 2 weeks ago I was working on the battery pack in my
HP Cesium which was dead. Charging it externally at C/10 the terminal
voltage never came close to what it should have been. This package is
comprised of 20 1/2 size D cells. 7 of them were shorted. The date code was
1995 on the package, which I felt was not that old. I zapped the 7 cells and
they all came alive. Then I charged them and all looked good. Then I
discharged them at a 1 amp rate, the package is rated for 2.4 AH. I went
through this exercise about 4 or 5 times, charge, discharge. Worked every
time. I usually charged it during the night where I did not mind the long
time of 10 hours. After the last charge cycle I just let it sit for over a
week. That is usually when the bad ones show up. It still holds up fine and
seems to meet rated capacity. Each cell is less than 10 millivolts from each
other. I lucked out on this one as 1/2 Ds are not very common. There have
been others when I was not so fortunate. But since it is bad, one has
nothing to loose by trying. Regards - Mike
Mike B. Feher, N4FS
89 Arnold Blvd.
Howell NJ, 07731
(732) 901-9193
2:51 p.m.
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4 p.m.
Yeah that was just a lazy typer's shorthand for LapTop. I had forgotten that
term. I've got an old tube portable with the 4-pin plug, that used them. Where
the term B voltage came from I believe. You can still get them but they are
very expensive. The battery was likely bigger than this portable itself. I've
thought of using 2 power supplies to see if I could get it working. I've also got
a raft of old tubes(valves--much more descriptive)
Lawrence
Andy Holt wrote:
I seem to remember a huge battery with a four-pin-socket, that you got
HT with your LT, and the HT was 90V. Half the weight of a good old fashioned
radio seemed to be made up of the battery, and it always seemed a very long way
home from the jumble sale (I believe that the over-the-ponders call these
'rummage sales'). At the age of 9 or 10, the sheer size and weight of the radios
meant that you always did something with them after you had fought them into the
house...
Cheers,
Dave.
lgwalker(a)mts.net
bigwalk_ca(a)yahoo.com
What's a LT battery ?
To me (and, I expect, to Tony) it powers the heaters in a valve (tube to
those across the herring pond) portable radio :-) An almost obsolete term.
In the message you were looking at, it appears to be LapTop (normally a
Nicad)
Andy
2:51 p.m.
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7924
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14 comments
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participants (11)
-
andyh＠andyh-rayleigh.freeserve.co.uk -
ard＠p850ug1.demon.co.uk -
bshannon＠tiac.net -
carlos_murillo＠epm.net.co -
dave＠naffnet.org.uk -
dtwright＠uiuc.edu -
ghldbrd＠ccp.com -
lgwalker＠mts.net -
n4fs＠monmouth.com -
rigdonj＠cfl.rr.com -
sipke＠wxs.nl