You are correct that a battery can in fact be damaged by to much amperage.
But this damage is only because it wasn't trickle charged (low amperage) but
instead quick charged (high amperage). But then again that doesn't stop many
manufactures from making such chargers. As far as the diode, you half
correct. A diode can in fact be damaged by over amperage since it's a
component that does run inline of a wire. But the truth of that is only if it
flows that much. Now to flow that much current there must be something
drawing that much on the other end and it's overloading it's ability.
So, lets make an example, a simple circuit if you will. Imagine an AC power
supply, say supplying a 12v 2amp signal. On both power leads a diode (cathode
and anode pointing in opposite directions on either pole) and a LED in
parallel to the supply (hope that makes sense), anyway, if the LED is rated
at a minute 50ma, it's using that full 50ma supplied by the supply even
though the supply is capable of flowing 2A. So what will the diodes see,
exactly, 50ma across both. Ok, lets say the diode has a 1A threshold and
instead of a LED you use a 2A lamp, then the diodes will see a 2A load which
after time will burn them out. So anyway, I've still made my point. Amperage
pull will only be what is used, not what the battery or supply can produce.
And as long as you design your circuit correctly (with the correct parts for
the demands), you won't have to deal with blown diodes for example.
Jake
[EMAIL PROTECTED] wrote.......>
There are many unfortunate statements above ("simple electronics
specifies..." is so wrong that it isn't even wrong!). Short story: There are
many, many components in electronics which behave nonlinearly. Even a
battery, if
charged with seemingly small overvoltages, can exhibit catastrophic
behaviors. A diode is a device where, if you apply a mere extra 60mV (that's
0.06 volts) or so directly across it, the current can go up by a factor of 10!
It does not "know" what current it "needs", and will happily, destructively
demonstrate that truth for you.
Another way to look at it: You applied nearly a 50% overvoltage. If it were a
resistive load, the current would have gone up by ~1.5x, too, for a power
increase to ~2x the nominal value -- that's a lot, even for a resistor.
But you weren't feeding a resistor -- it's a much more complicated thing!
--
Prof. Thomas H. Lee
Center for Integrated Systems, CIS-205
420 Via Palou Mall
Stanford University
Stanford, CA 94305-4070
http://www-smirc.stanford.edu
650-725-3709 ph, -3383 fax
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