Well, that turns out to be completely wrong. The LED actually has a very significant internal resistance.
Really? Citation please?
Or are you being pedantic? The wire leads have a non-zero resistance. The real world LED semiconductor will of course not be "ideal". Is that what you are talking about?
At the Vf, the depletion region of the semiconductor, there is no internal resistance. Unless you're playing games with theoretical ideals vs real world fabrications like the component leads. The semiconductor becomes a conductor but not a superconductor.
And this also turns out to be completely wrong. There is an immense difference between the voltage drop of a LED and a short circuit.
Again, citation please. Unless you mean the voltage is dropped by the diode so the short circuit current through the non-super-conducting wires will be lower than it would be if the LED were replaced with wire.
So please, provide a source for LEDs having a "significant internal resistance" that makes anything I said "completely wrong".
And in any case, what are you trying to accomplish by your post? Even if my understanding of semiconductors is completely wrong, is your post helpful to anyone who wants to learn to connect and LED or is it just harmful and confusing. Is anything you said of help to the OP? Can he pick an LED from data sheets that is better to short across a battery?
These forums have become a very unpleasant place with people like you trying to show off how smart you are at the expense of people who come here genuinely trying to learn how to build things with their Arduino. Your tone is harsh and unpleasant, you are offering nothing of use to the OP. Your snippy little comments "completely wrong" are not useful at all. If I am wrong, rather than just trying to be an offensive snob, why don't you explain what you mean to make it a positive experience. And if I am right, why are you just trying to confuse everything. There is no such thing as a short circuit because all wire has resistance. And there is no such thing as an ideal semiconductor. How is that remotely relevant to this thread?
I really would like to hear what you mean in the case I am wrong. But even if you did have a point, you post in such a nasty way you are a negative influence on these forums, and I know i'm not this first to say this.
This combined with the internal resistance of the LED is used to effect in the popular $1 9-LED torches which have three "AAA" cells and no apparent current limiting at all.
I actually took the time to google that.
First, you have all 9 LEDs in parallel with no resistors. Are you suggesting that that is a good design? Or do you want to say there there really is resistance for each LED because the copper trace has a non-zero resistance. It is impossible to connect any components directly in parallel without resistance because all conductors have resistance.
Those lights are so shoddily made the battery spring alone has significant resistance. They are cheap Chinese junk that is designed to just last long enough to sell. It's actually usually the wiring or switch that fails long before the LEDs have a chance to be burnt out.
Are you seriously recommending someone who comes here to learn about electronics and wants to build a hobby project take design tips from that school of thought. Those flashlights are not so much designed as thrown together without any thought. They are horrible pieces of engineering that don't really work.
So how is that remotely useful to the OP or anyone else who comes along and wants to know how to wire an LED.
I get that you want to convince people how smart you are.