Batteries

Feb 14 21:05 UTC 1997

Today, in a hurry, I went into a Rite-Aid to buy a battery.
I needed a 9-volt for an electronic tuner.  Usually I buy
batteries in the checkout lane of either Target or Krogers,
so I tend to not pay attention to how much they cost.  But
when buying just the battery the price kinda just stood there,
staring me down - $3.49.  We're talking one battery.

Naively I asked if maybe Energizer batteries were less than
the Duracell.  Nope.  So then I got to thinking about non-alkaline
batteries which are something like two for $1.39.  And what about
rechargeable batteries?

What is the difference between alkaline and "classic" batteries?
Is one more prone to leakage?  Why the big difference in cost?
Are rechargeable batteries cost effective and better for the
environment?

response 2 of 75:

Feb 15 00:44 UTC 1997

re #1 Yes but you can recharge them *hundreds* of times at least the
nickle cadmium.  Much cheaper and better for the environment in the long
run.  The best place for rechargables is rat shack. 

response 4 of 75:

Feb 15 01:45 UTC 1997

Batteries?  What are those?  Oh, you mean those large things that you put in
your notebook so that after it's been plugged in for a while, you can use it
without a power cord?  Or maybe those heavy monsters that start your car? 
"Stick to a power cord.  It has the longest service life on one charge." I
always say. :)

response 6 of 75:

Feb 15 02:44 UTC 1997

I generally use NiCad rechargables, since they are much cheaper in the 
long run.  However, some applications with very low power use (such as 
electronic tuners) can use just about anything.  Things that draw a lot 
of power, such as CD players or Newtons, work *great* with NiCads.

Rayovac makes a "reusable alkaline" called "Renewal", but it hasn't 
proven to be very effective.  You get maybe 10-20 times the life of a 
normal alkaline with the special charger.  These are good for things 
like small flashlights, and would probably be great for electronics if 
they made a 9v version.  I found enough weak cells in the ones I used to 
sour me on the concept, though.

response 8 of 75:

Feb 15 07:13 UTC 1997

Omni is right. Alkalines are the best kind of non-rechargeables. The last
pack of 9-volt alkalines I bought from Radio Shack cost 4/$7 - *but*, they
have periodic sales at 3 packs for the price of 2. That makes a 9-volt
battery cost $1.18. Stock up: alkalines also have a long shelf life (as well
as having a higher capacity/weight).

NiCads are the best low-weight rechargeables currently. I also use them in
amateur radios, as does omni. I've had very good life from them. As mentioned,
they have very high current capacity - they are built into "Dustbusters"
(and you can replace them yourself). Don't leave nicads on charge for long
times, and they need to be discharged to ca. 1 volt each periodicially (but
never totally discharge them). The best prices for NiCads are via mail order.

response 10 of 75:

Feb 15 14:12 UTC 1997

I use mostly NiCads, but NiCads give less power than Alkalines.  (Like a AA
NiCad may give 1.3 or 1.4 volts instead of 1.5).  Some products (like my
digital camera) won't work on them (actually I have some "Golden Power" NiCads
tha work with the camera, but my Panasonic NiCads don't have enough power).
Since I have some stuff that seems to need alkalines, I have a fancy charger
that does both alkalines and NiCads.  Yes, with the right technology, you can
recharge alkalines.  It takes a long time, and has to be done with care but
it works.  Alkalines recharge best if you don't run them down, just "top them
off" regularly.  NiCads have the longest life if you do discharge them between
use.  The charger I have discharges NiCads before recharging them, and for
either type of battery, automatically shuts off when the battery is fully
charged (over charging can be a problem).

response 12 of 75:

Feb 15 18:38 UTC 1997

  Scott, while it is true that my NiCads are made for my radio, the point was
that W&W will provide any NiCad that you may need, and you might want to go
there instead of Meijer, or Target.

response 14 of 75:

Feb 15 21:15 UTC 1997

i have seen a few ads for chargers which supposedly work with single-use
alkaline batteries, but i have no info on performance.

response 16 of 75:

Feb 16 00:48 UTC 1997

would you please elaborate on the "depolarization" mechanics for those of us
less knowledgeable in the matter?

response 18 of 75:

Feb 16 06:10 UTC 1997

Well, not bad for a ham.. 8^}... The electrodes in an alkaline battery are
powdered zinc (Zn) at the anode (-), and powdered manganese dioxide (MnO2) 
at the cathode (+). During discharge, the reactions at each electrode are

  anode               2Zn  +  8(OH-)  =  2Zn(OH)4(-2)  + 4e(-1)
  cathode    3MnO2  +  4e(-1) + 2H2O  =  Mn3O4  +  4(OH)(-1)

where (OH)(-1) is the hydroxide ion, Zn(OH)4(-2) is the zincate ion,
Mn3O4 is manganese tetroxide (solid), and e(-1) are electrons.

As the discharge proceeds, (OH)(-1) is consumed at the anode, reducing its
concentration. Fresh (OH)(-1) must diffuse in from the center of the cell
to replace it. This is a slow process, so the depleting (OH)(-1) reduces
the cell voltage. Likewise, at the cathode, OH(-1) is produced, also diffuses
slowly, and accumulates, also reducing the cell voltage. The decrease of
(OH)(-1) at the anode and its increase at the cathode is called concentration
polarization. How can this be reduced?

If we apply a reverse current through the cell the anode reaction tends to
reverse, but it cannot, as hydrogen will be produced instead of zinc.  The
cathode reaction also tends to reverse, but both MnO2 and oxygen are
produced there. However throughout the battery during "recharging" the
current is carried by (OH)(-1) ions, *removing* them from the cathode
electrode vicinity and building them up again at the anode electrode
vicinity. The current reduces the concentration polarization. Neither zinc
(Zn), or manganese dioxide (MnO2)  completely are reformed, so the battery
is not really being recharged. You just recover some of the "kick", but
not the active ingredients (Zn and MnO2). 

response 20 of 75:

Feb 17 14:24 UTC 1997

I also prefer NiCad and Alkalines.  When carbon / zink batteries die
they start leaking a very corrosive goo that will eat most metals and,
more often than not, destroy whatever they are in.  NiCads and Alkalines
may leak a little if left dead for a long time but the residue can be
washed off with water and is not very corrosive.  Sometimes this residue
will also form and insulating barrier on a battery contack, making the
user think the device is broken.  This stuff can be chipped away though.

response 22 of 75:

Feb 17 20:29 UTC 1997

there is a fairly new techniqe for recharging nicads in which the battery
does not have to be fuly depleted first. however, that said (and paid
for with a pricy recharger) ... nicads have a 'memory' about how much
they are 'required to work.'
  
if nicads are discharged/worked only, oh, say, 1/4 of their potential
and then recharged... they 'remember' that they were only re2quired to
work 1/4 of their capacity ... therefore that's all they will work in
the future.
  
i don't remember if the memory is immediate or if it takes a few cyclings
at some lesser usage to develop the memory... but nicads learn how to
cop out of working up to full potential.
  
i just shake my head at ppl who put their wireless phone right-back-in-the-
base-unit after a phone call (as one example). i have used phone nicads
for periods of almost 3 years before they finally die. after a full charge
when newly acquired .... don't put the phone in the base unit until and
unless the damn thing dies totally. 
  
same with those power tool batteries (which now are
interchangable/replaceable).

drain them completely before recharging.
  

response 24 of 75:

Feb 18 10:29 UTC 1997

I keep hearing that the NiCad "memory effect" is practically an urban legend,
since the design flaw that causes it was fixed years ago.  I've also read that
a similar effect can be created by constant charging.  My NiCads are mostly
used in the "ideal" situation, a (nearly) full charge/discharge cycle every
time.