Hi all,
I have a couple of basic questions on batteries. I only know very
little about electronics, electricity, so please bare with me for the
silly questions.
There AA, D, C batteries in the market (Duracell, etc). Does anyone
know what amphare (current) for these batteries give?
AA batteries can give peak current of 10A or more. However, if you do that
you will quickly exhaust them. The capacity of batteries is usually
measured in 'amp hours' (or milli-amp hours). For example, assume your AA
cell is 1000 milliamp-hour. That means that if you draw 1A for 1
hour, or 100mA for 10 hours, or 10mA for 100 hours, you will exhaust the
battery. Unfortunately, the rate at which charge is pulled out (the
current) affects the actual amount of charge you can get. Generally, the
more current, the less total charge can be obtained.
Current also affects the voltage, since the battery can be thought of as
a resistor in series with a voltage source. As a cell discharges, it's
internal resistance increases. Thus, it's voltage goes down...
If I have 1.5V AA battery, and for an
example, it gives 50mA. (I have no
idea if it gives 50mA.) If a circuit needs 1.5V, but 100mA, what do I
need to do?
Thanks!
There are different kinds of AA cells. Alkaline cells are the main kind of
'primary' cell, which basically means non-rechargeable. "secondary" cells
are rechargeable, and come in various tasty flavors, like nicad, nimh,
liion, etc. nicad and nimh cells are both 1.2 volts nominal, whereas liion
cells are 4.2V. They come in different 'capacities', amp hours. So, you
can get a 1700 mAH nimh cell, or a 3000mAH nimh cell. They are both 1.2V,
but one will last longer given a particular current requirement. Some
cells are also constructed to have different maximum current capabilites.
For RC aircraft use, for example, you want to have high max current,
because the electric motors take large currents. For a tape player, you
may only want 100mA, so a battery that lasts longer, but doesn't allow
larger max currents can be used.
You can find out more by going to the duracell site, and looking at the
battery specifications.
Look here:
http://www.duracell.com/oem/
--
Regards,
Bob Monsen
If a little knowledge is dangerous, where is the man who has
so much as to be out of danger?
Thomas Henry Huxley, 1877