Prev: Health care update
Next: Through Hole vs. Surface Mount
From: Archimedes' Lever on 30 Mar 2010 03:29
On Mon, 29 Mar 2010 07:37:26 -0400, Hammy <spam(a)spam.com> wrote:

>On Sun, 28 Mar 2010 22:51:21 -0500, Gary Peek
><mylastname(a)mycompanyname.com> wrote:
>
>>Archimedes' Lever wrote:
>>> They end up working like slow charge, quick discharge, leaky
>>> capacitors. Really, really bad ones.
>>
>>That describes what I see them doing. Fortunately I designed this
>>device with excess battery capacity, so I'll be able to get away
>>with operating it for a while before I need to replace the battery
>>pack. Thanks for the insight.
>>
>>
>>--- news://freenews.netfront.net/ - complaints: news(a)netfront.net ---
>
>Wiki has some decent general info on various battery technologies.
>Heres NiCaD.
>
>http://en.wikipedia.org/wiki/Nickel-cadmium_battery
>
>"The batteries are more difficult to damage than other batteries,
>tolerating deep discharge for long periods. In fact, NiCd batteries in
>long-term storage are typically stored fully discharged. This is in
>contrast, for example, to lithium ion batteries, which are highly
>volatile and will be permanently damaged if discharged below a minimum
>voltage."


The only drawback to NiCad is that they typically have only a third the
capacity that Nimh have.

My AAs are only 600mA/h, whereas my AA Nimhs are 2200 or 2500 mA/h.

That makes them a non-useable item in a camera or other high draw
device, because they would show low battery within five minutes or so.
From: Archimedes' Lever on 30 Mar 2010 04:55
On Mon, 29 Mar 2010 12:58:26 -0700, mike <spamme0(a)go.com> wrote:

>Gary Peek wrote:
>> Any NiCad battery experts out there? For a NiCad battery pack that
>> has not been in use for a long time, like a year, and has discharged
>> well below the point of operating the circuit it was powering, what
>> is the best way to restore it to use? Is charging it in the normal
>> manner good enough, or are a couple of charge/discharge cycles better?
>>
>> --- news://freenews.netfront.net/ - complaints: news(a)netfront.net ---
>
>beware shorted cells.
>I've seen many a wall-wart melted because they're designed to charge
>all-good cells. When one or more cells shorts, the wall-wart has
>insufficient current to blow out the short, so it burns itself up
>trying to stuff unlimited current into fewer cells. That can also
>over heat the good cells. Happens a lot with power tools.
>

Well, it does NOT happen with the wall wart type you describe. For one
thing, they charge in pairs, and one pair does not affect the other, so
at the very most, you would surge ONE already charged battery.

However, they also nearly all have a watchdog circuit that checks the
batteries at the first insertion and application of power (plugging it
in). I have never seen one that could or would charge or apply a charge
or surge, that could heat it or the battery up to the melting point of
the plastic, much less its flash point.

>It's safer to use an external supply to zap any shorts and get the
>pack voltage up past 1V/cell before attempting to use the stock charger.

Seal packs are a different case, for sure. Single cells, had they
NEVER been commonly referred to as "batteries" to begin with, would have
solved any ambiguities that still exist there. Folks would understand
discussions about memory effect, etc. far better.

Parts is parts. We should call a single cell a cell and a battery a
battery.

They are AAA, AA, C, and D CELLS. It is a 'Nine Volt BATTERY'.

The BATTERY pack on your computer, drill, Portable DVD player, etc.,
are made up of two or more CELLS of various and sundry sizes and voltages
and electro-chemical energy storage technologies.
From: Kevin McMurtrie on 31 Mar 2010 02:13
In article <honuq6$ptu$1(a)adenine.netfront.net>,
Gary Peek <mylastname(a)mycompanyname.com> wrote:

> Any NiCad battery experts out there? For a NiCad battery pack that
> has not been in use for a long time, like a year, and has discharged
> well below the point of operating the circuit it was powering, what
> is the best way to restore it to use? Is charging it in the normal
> manner good enough, or are a couple of charge/discharge cycles better?
>
> --- news://freenews.netfront.net/ - complaints: news(a)netfront.net ---

They're fine as long as they aren't leaking, haven't been reverse
charged, and haven't been cooked in a dumb charger until they vented.

If the charger doesn't like them, manually give them 1C current until
they're warm. Don't forget to check them! If they don't provide enough
current, run them completely dead then recharge.
--
I won't see Google Groups replies because I must filter them as spam
From: JosephKK on 31 Mar 2010 14:07
On Sun, 28 Mar 2010 11:06:30 -0500, Gary Peek <mylastname(a)mycompanyname.com> wrote:

>Any NiCad battery experts out there? For a NiCad battery pack that
>has not been in use for a long time, like a year, and has discharged
>well below the point of operating the circuit it was powering, what
>is the best way to restore it to use? Is charging it in the normal
>manner good enough, or are a couple of charge/discharge cycles better?
>
>--- news://freenews.netfront.net/ - complaints: news(a)netfront.net ---

NiCad reconditioners work by deep cycling the cells a couple of times. It
does not help NiMH cells though. 100% deep cycling is done in satellites
that use NiCad batteries.
As for dumping a large cap across a cell to blow dendrites out, i have had
good luck with that as well, though once i just hooked one across a car
battery for a fraction of a second (using thin wire, it started smoking).

YMMV
From: GregS on 31 Mar 2010 16:04
In article <8c37r5dqkvl3fqhpqbr494dvhke38l28kt(a)4ax.com>, "JosephKK"<quiettechblue(a)yahoo.com> wrote:
>On Sun, 28 Mar 2010 11:06:30 -0500, Gary Peek =
><mylastname(a)mycompanyname.com> wrote:
>
>>Any NiCad battery experts out there? For a NiCad battery pack that
>>has not been in use for a long time, like a year, and has discharged
>>well below the point of operating the circuit it was powering, what
>>is the best way to restore it to use? Is charging it in the normal
>>manner good enough, or are a couple of charge/discharge cycles better?
>>
>>--- news://freenews.netfront.net/ - complaints: news(a)netfront.net ---
>
>NiCad reconditioners work by deep cycling the cells a couple of times. =
>It=20
>does not help NiMH cells though. 100% deep cycling is done in satellites=
>=20
>that use NiCad batteries.
>As for dumping a large cap across a cell to blow dendrites out, i have =
>had=20
>good luck with that as well, though once i just hooked one across a car=20
>battery for a fraction of a second (using thin wire, it started smoking).
>

Any one I tried to restore would go bad next discharge cycle.

I have left my Johnson Walkie Talkies go for a long time, up to 3 years, and the thing
will still tun on and the receiver will work. Last time I checked, it
would not turn on. Time to recharge !!!

Those Varta 1960's nicads will never die.

greg
First  |  Prev  |  Next  |  Last
Pages: 1 2 3 4 5
Prev: Health care update
Next: Through Hole vs. Surface Mount