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

On 10/05/2007, at 8:21 AM, M. Kowal wrote:
> Hello Douglas:
> Woody's excellent comments notwithstanding, I believe that *some*
> Newton batteries can be given a bit more mileage with the freezer
> technique. This technique is one part science, one part faith, and
> one part folk medicine. I'll try to explain the process in simple
> layman's terms.
>
> The idea as I understand it is this: the electrolytic compounds
> within the battery cells use certain specific electron flow "paths"
> as they charge and discharge repeatedly. I don't think this occurs
> on the molecular level, but anyway... The goal is to "disrupt" the
> existing electron flow "paths" within the electrolytic compounds
> and let the electron flow establish a new, different "path" for
> future charge and discharge cycles.
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

-- 
This is the NewtonTalk list - http://www.newtontalk.net/ for all inquiries
Official Newton FAQ: http://www.chuma.org/newton/faq/
WikiWikiNewt for all kinds of articles: http://tools.unna.org/wikiwikinewt/