Simple question about batteries

[Andrew Falanga]

Hi everybody,

I hope this is a correct forum to ask this question. Actually, I have several and if the questions are better asked by pointing me to web sites that's fine.

First, what's the difference between alkaline, Ni-Cad and Ni-MH batteries? That is, what's different beyond their constituent parts?

Second, and last (ok so not several), is it true that one doesn't have to concern one's self with what type of battery is used to power a particular device, but does have to be concerned what type of battery is used in a recharge?

For example, I have a calculator that uses 4 AAA batteries. Does it matter if I use alkaline, Ni-Cad, Ni-MH, etc. (so long as their AAA size)? Further, though this calculator doesn't include a recharging capability am I correct in thinking that it DOES matter in what type of circut the batter in question is recharged (excluding alkaline, but only because I've never seen a recharger for such a battery)?

It woudldn't matter would it? I mean, so long as the voltages are consistent, the device is still going to draw it's designed amperage. What difference does it make where those electrons come from right?

Andy



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[nemo]

Andrew Falanga <andy@spam.me.not> wrote in message
news:20040211121243.06ffbfd4.andy@spam.me.not...

Hi everybody,

I hope this is a correct forum to ask this question. Actually, I have
several and if the questions are better asked by pointing me to web sites

that's fine.

First, what's the difference between alkaline, Ni-Cad and Ni-MH batteries?
That is, what's different beyond their constituent parts?

Second, and last (ok so not several), is it true that one doesn't have to
concern one's self with what type of battery is used to power a particular

device, but does have to be concerned what type of battery is used in a
recharge?

For example, I have a calculator that uses 4 AAA batteries. Does it
matter if I use alkaline, Ni-Cad, Ni-MH, etc. (so long as their AAA size)?

Further, though this calculator doesn't include a recharging capability am I
correct in thinking that it DOES matter in what type of circut the batter in
question is recharged (excluding alkaline, but only because I've never seen
a recharger for such a battery)?

It woudldn't matter would it? I mean, so long as the voltages are
consistent, the device is still going to draw it's designed amperage. What

difference does it make where those electrons come from right?

Andy


I believe Alkaline are more-or-less improved versions of the old Zinc Carbon

ones. These are "Primary Cells" and are therefore not rechargeable. NiCds
and NiMHs are "Secondary Cells" (nice ancient bit of Jargon there) and are
rechargeable.

NiCds were developed from the old NiFe Nickel Iron batteries which were
incredibly durable and much used in military equipment, miners' lamps etc.

NiMHs, Nickel Metal Halide, are the latest, have much higher capacity that
NiCds - for AA cells: 1100mAh as opposed to 600mAh for a NiCd, so an AAA
would probably be around 600mAh in spite of its smaller size.

NiMH are also supposed to be more reliable. I say 'supposed to be' because,
in the dim and distant days when I had a job, we had terrible problems
caused by about 30% of brand new Varta ones having virtually no capacity at
all! I'd imagine they've got the bugs out of them by now though.

Another advantage of NiMHs is that they are less prone to the "Memory
Effect" exhibited by NiCds. They can also be charged more quickly using a
constant-current charger although they *can* be charged using a charger
intended for NiCDs except it takes proportionately longer.

Hope this helps,

Nemo

 

[Sheldon]

First, what's the difference between alkaline, Ni-Cad and Ni-MH batteries?
That is, what's different beyond their constituent parts?

Briefly, Ni-Cads are very rugged, can be recarged many times, but tend to
have a memory effect. If you only use it for brief periods, that's all it
will give you even when recharged. Ni-MH batteries are more friendly to the
environment, and can be used for brief periods and then recharched again
while still giving you the full rated capacity when needed.

Second, and last (ok so not several), is it true that one doesn't have to
concern one's self with what type of battery is used to power a particular

device, but does have to be concerned what type of battery is used in a
recharge?

Wrong! Since Ni-Cads and Ni-MH batteries lose their charge over a fairly
short period of time, about 1 percent a day I think, you would never use
them in devices that sit idle for long periods yet need to kick in for an
emergency. For example, you would never use them in smoke detectors,
backups for clocks, clocks in general, and I probably would think twice
about using them in flashlights that don't have them preinstalled from the
factory. Rechargeables seem to work best in devices you plan on using
regularly, and devices that you use often enough to run the batteries down
to nothing, like CD players.

For example, I have a calculator that uses 4 AAA batteries. Does it
matter if I use alkaline, Ni-Cad, Ni-MH, etc. (so long as their AAA size)?

Further, though this calculator doesn't include a recharging capability am I
correct in thinking that it DOES matter in what type of circut the batter in
question is recharged (excluding alkaline, but only because I've never seen
a recharger for such a battery)?

The voltage rating on rechargeable batteries is lower than normal batteries,
but they hold that voltage for a longer period then drop off quickly. So,
it's probably okay to use them in just about any device, but if that device
has a low battery indicator it may not give you enough notice to change the
batteries before you lose anything stored in memory. Some devices have
adjustments for this, but not many. And remember, if you don't use your
calculator often, rechargeable batteries will die just sitting on the shelf.
Alkaline batteries might be a better choice, only because they can sit for
years and hold a charge. When you grab your calculator an alkaline battery
will pick up right where it left off

It woudldn't matter would it? I mean, so long as the voltages are
consistent, the device is still going to draw it's designed amperage. What

difference does it make where those electrons come from right?

Actually, in high-draw devices like digital cameras, a Ni-MH battery can
last about 4 times as long as an alkaline. Check out sites like Rayovac's
for some pretty good info on rechargeable batteries and chargers. They also
make a rechageable Alkaline that works very well in some applications (very
long shelf life, cost effective, but isn't perfect for every application).

Hope this info helps.

Andy



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