Re: [NTLK] How do I freeze the battery for MP2x00?

Hello Adam:

Thank you for the excellent explaination!

I did a bunch of home-brew experiments with chemicals and electrical currents when I was a kid (I got an early start in elementary school, when my dad brought home some glass apparatus from the University). The nature of the experiments and my financial status as a kid required that I extract chemicals from old batteries and dry cells (magnesium hydroxide, zinc strips, carbon rods, etc). I loved the electrolysis/water displacement experiment, separating water into hydrogen and oxygen. Home-made pyrotechnics were cool, too. I'm probably lucky that I did not blow up my parents' house. My best friend had a bigger chemistry set-up than I, and his parents gave him a larger work area. We used an old steel bucket in his dad's basement to discard old experiments. It had cool colored crystalline growths on its sides, and I think it started smoldering once or twice (some funky exothermic reaction). We were probably in the fifth or sixth grade and thought the bucket was cool, but it
 was very likely a miniature toxic waste site. We're probably lucky it did not kill us... :O)

I also experimented with *non-rechargeable* batteries and an old Lionel train transformer. Results were mixed. You could get an *ordinary* Eveready "D-cell" battery to take a new charge for a short period of time, but sometimes the results were a bit more *violent*. When they say "Do not recharge", believe them!

Then there was the phase where we rummaged in the dumpster behind the RCA repair place for copper wiring and vacuum tubes...

Matt K.
Detroit, Michigan USA

Adam Goddard <pashosh@tpg.com.au> wrote:
A more accurate description is that the compound's structure is
crystalline in nature. Did you ever do the electrolysis experiment in
high school science with the jar of copper sulfate, the copper bar
and the iron/zinc bar, and you passed current through it? You got a
build up of copper gunk on the iron/zinc bar. Similar process happens
in batteries, only with rechargeable batteries, you can reverse the
process by applying current in the opposite direction. An effect
especially pronounced in NiCad cells is the Memory Effect, where the
continual charge to a certain point and discharge to a certain point
over and over leaves a physical change in the crystal structure of
the electrolyte compound. This means that you can't charge past this
point, and will not get the best life out of your cells. The freezing
of the cells actually breaks most of the crystals that have formed,
due to the fact that liquids(the electrolyte is a semi-liquid paste)
expand when frozen. Banging them hard also helps jar the crystals out
of alignment and break off. This is the cheap and nasty way to bring
health back to an old cell. Using a battery Reconditioner will
discharge the cells to 0V each and then pulse current of varying
amounts and at varying time intervals in an attempt to destroy these
crystals. This site has pretty pictures:

http://www.batteryuniversity.com/parttwo-33.htm

Regards,
   - Adam Goddard

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