When that white crystalline material forms on th ends of the cells and the
impedance goes high and they become useless. What is that substance and how
harmfull is it ?
Is it the same process, in effect, that renders lead-acid cells uselss - a
build up of an insoluble salt so the ions cannot pass to/from the lead to
the electrolyte?

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

On Fri, 16 Dec 2005 14:58:20 -0000, "N Cook"
wrote:

When that white crystalline material forms on th ends of the cells and the
impedance goes high and they become useless. What is that substance and how
harmfull is it ?
Is it the same process, in effect, that renders lead-acid cells uselss - a
build up of an insoluble salt so the ions cannot pass to/from the lead to
the electrolyte?

The cells tend to leak if left discharged for a long period. How
harmful would depend on what you plan to do with it. Its not good to
eat and may kill you, pollute the environment, etc.. Cadmium is very
poisonous, nickel is poisonous, they may contain small/trace amounts
of mercury as well.

I don't know the chemistry of nicads, but do know they are radically
different from lead acid, so a different failure mechanism might be at
work.

Most of the cells I have experience with (back in the day) short
internally, If left in that condition, over time, they leak, or just
corrode from the inside out. Cells that have an internal short can
often be rejuvenated by burning the short out with a discharge of
heavy current through it. We used to build power supplies that would
charge a cap to dump energy into the short for that purpose.

Throw them out and get new rechargeable's. Once they leak, they've
had it.
--

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On Fri, 16 Dec 2005 14:58:20 -0000, "N Cook"
wrote:

When that white crystalline material forms on th ends of the cells and the
impedance goes high and they become useless. What is that substance and how
harmfull is it ?
Is it the same process, in effect, that renders lead-acid cells uselss - a
build up of an insoluble salt so the ions cannot pass to/from the lead to
the electrolyte?

I hope you are able to reply to this message. In the event you
touched that leaking chemical, you will die within 12 hours or less.
Its absorbed thru the skin and eats a hole thru your brain, eventually
devouring your entire brain. If you are still able to read this
message, you may no longer be able to comprehend it because your brain
is partially eaten away. I'd tell you to contact a doctor, but it's
too late. There is no way to stop this brain decay. However, there
is a possible light at the end of the tunnel. One out of 100 people
do survive. They have little if any remaining brain matter, but there
is enough left to remind them to breathe and keep their heart beating,
Most of them end up in Texas and join the rodeo. However one of them
went to Texas and later moved to Washington DC to become the president
of the United States. His name is George W. Bush. Doctors have
evaluated this man and found little working brain matter. They all
said it's a miracle he is alive.

Good Luck
You need it !!!

In article ,
default wrote:

On Fri, 16 Dec 2005 14:58:20 -0000, "N Cook"
wrote:

When that white crystalline material forms on th ends of the cells and the
impedance goes high and they become useless. What is that substance and how
harmfull is it ?
Is it the same process, in effect, that renders lead-acid cells uselss - a
build up of an insoluble salt so the ions cannot pass to/from the lead to
the electrolyte?

The cells tend to leak if left discharged for a long period. How
harmful would depend on what you plan to do with it. Its not good to
eat and may kill you, pollute the environment, etc.. Cadmium is very
poisonous, nickel is poisonous, they may contain small/trace amounts
of mercury as well.

I don't know the chemistry of nicads, but do know they are radically
different from lead acid, so a different failure mechanism might be at
work.

Most of the cells I have experience with (back in the day) short
internally, If left in that condition, over time, they leak, or just
corrode from the inside out. Cells that have an internal short can
often be rejuvenated by burning the short out with a discharge of
heavy current through it. We used to build power supplies that would
charge a cap to dump energy into the short for that purpose.

Throw them out and get new rechargeable's. Once they leak, they've
had it.

BAD IDEA! The cadmium in them is very toxic. That's why you should be
careful about those crystals from a leaky one, and also why you should
never "throw them away", but dispose of them properly as toxic waste.

NiMH use a different chemistry, and are nowhere near so bad.

Isaac

"default" wrote in message
...
On Fri, 16 Dec 2005 14:58:20 -0000, "N Cook"
wrote:

When that white crystalline material forms on th ends of the cells and
the
impedance goes high and they become useless. What is that substance and
how
harmfull is it ?
Is it the same process, in effect, that renders lead-acid cells uselss -
a
build up of an insoluble salt so the ions cannot pass to/from the lead to
the electrolyte?

The cells tend to leak if left discharged for a long period. How
harmful would depend on what you plan to do with it. Its not good to
eat and may kill you, pollute the environment, etc.. Cadmium is very
poisonous, nickel is poisonous, they may contain small/trace amounts
of mercury as well.

I don't know the chemistry of nicads, but do know they are radically
different from lead acid, so a different failure mechanism might be at
work.

Most of the cells I have experience with (back in the day) short
internally, If left in that condition, over time, they leak, or just
corrode from the inside out. Cells that have an internal short can
often be rejuvenated by burning the short out with a discharge of
heavy current through it. We used to build power supplies that would
charge a cap to dump energy into the short for that purpose.

Throw them out and get new rechargeable's. Once they leak, they've
had it.
--

----== Posted via Newsfeeds.Com - Unlimited-Unrestricted-Secure Usenet
News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+
Newsgroups
----= East and West-Coast Server Farms - Total Privacy via Encryption
=----

Googling around , the electrolyte in NiCads would seem to be potasium
chloride and the white crystalline buidup is probably just potassium
carbonate.

On 12/17/05 8:31 AM, in article , "N Cook"
wrote:

Throw them out and get new rechargeable's. Once they leak, they've
had it.

Please, never THROW OUT any batteries. Take them to Radio Shack or your city
haz-mat center so they can be recycled. It scares me to consider all the
batteries that get thrown in the trash, which then go on to leach their
toxic substances into groundwater.

Be

On Sat, 17 Dec 2005 17:02:03 GMT, BE
wrote:

On 12/17/05 8:31 AM, in article , "N Cook"
wrote:

Throw them out and get new rechargeable's. Once they leak, they've
had it.

Please, never THROW OUT any batteries. Take them to Radio Shack or your city
haz-mat center so they can be recycled. It scares me to consider all the
batteries that get thrown in the trash, which then go on to leach their
toxic substances into groundwater.

Be

What about the plain carbon acid flashlight batteries? Are they bad
to dispose? I dont think recyclers even take them, or the common
alkaline batteries?