Re: Anacron and laptop hibernation

The message <48b7ba4a$1_1@xxxxxxxxxxxxxxxxxxxxxx>
from "Geoffrey Clements" <geoffrey.clementsNO@xxxxxxxxxxxxxxxxxx>
contains these words:


"Will Kemp" <will@xxxxxxxxxxxxxxxx> wrote in message
news:oJCtk.129433$Ft5.55359@xxxxxxxxxxxxxxxx
Johnny B Good wrote:
The message <48b65652$1_1@xxxxxxxxxxxxxxxxxxxxxx>
from "Geoffrey Clements" <geoffrey.clementsNO@xxxxxxxxxxxxxxxxxx>
contains these words:


"Johnny B Good" <jcs.computersbutt@xxxxxxxxxxxxxxxx> wrote in message
news:313030303737303648B5F47D33@xxxxxxxxxxxxxxxxxxx
The message <Koitk.15885$f%6.8190@xxxxxxxxxxxxx>
from Will Kemp <will@xxxxxxxxxxxxxxxx> contains these words:


[snip]

Lead acid can tolerate reverse charge, the trick with lead acid is to
avoid leaving them in a sulphated (discharged) state for any protracted
period (24 hours maximum usually being the 'safe' period oft quoted).

Reverse charging a NiCad, NiMH, or LiOn cell is a definite 'no no'.

eh? - what do you mean "reverse charge"? Your either putting
charge into
a battery or taking it out (or neither).

Sigh! Whenever you have a string of cells (a battery), the one with the
least capacity compared to its neighbours, can become reverse charged if

There's no need to sigh, mate. I'm sure you weren't born knowing this
stuff. Everyone's got to learn somehow.


No problem Will, it happens that I know what "reverse charging" is
it's just
that the OP managed to press a couple of buttons with me because:
1. The statement was thrown into the thread without any explanation
2. I hate the term "reverse charge" even though it's very popular because
the concept of "reverse charge" is nonsense to me, rather "reverse bias"
seems a much better term to use as it better describes what's happening
IMHO.

Well, thanks for making the above admission. I hope my missive was to
your satisfaction. :-)

Regarding point 1, I had 'explained it' with my reference to lead acid
cells being able to tolerate reverse charging... where the process _IS_
exactly that (the first commercial lead acid cells, used a process of
charge, discharge, _reverse_charge_, discharge, recharge cycling to
bring their capacity up)[1]

Point 2, That seems to be a matter of semantics, yes, the "reverse
charge", unlike in the lead acid case, doesn't reverse charge the cell
as such, merely damages them. Nevertheless, they are recieving a
reversed charging _current_ from the reverse bias _voltage_ due to the
discharge current from the remainder of the cells in the battery. It's
exactly the same process as connecting them to a charger the wrong way
round.

[1] From memory, the process was known as the Plante forming process (or
something similar). The cell would be assembled with pure lead plates
for both electrodes and filled with diluted sulphuric acid. At this
stage, the result was a low capacity battery with both electrodes in the
fully negative state (i.e. uncharged).

The first charge would convert the surface of the positve electrode to
the porous red led form, leaving the negative electrode as pure lead.
The cell would be discharged converting the surface of both electrodes
to lead sulphate and then the cell would be reverse charged to convert
the non-porous 'negative' electrode surface into the porous red lead
form whilst the 'positive plate would be converted to pure lead, keeping
the porous structure of the initial charge. Each successive cycle would
deepen the penetration of the porous layer until a final practical limit
had been reached.

Although the cells produced were very durable, it was a time and energy
consuming process which was soon replaced by a method where the plates
were preformed using seperate chemical and mechanical assembly processes
for each electrode type which resulted in the "Dry Charged Cell"
requiring merely the addition of electrolyte to bring them into service.

--
Regards, John.

Please remove the "ohggcyht" before replying.
The address has been munged to reject Spam-bots.

.

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