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As far I know the power electricity is flow of electrons from anode to cathode of the battery. So basically the electrons flow through the circuit and return to cathode. Why can't we reuse these returned electrons to create an infinite battery ?

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closed as unclear what you're asking by Andy aka, Enric Blanco, pipe, uint128_t, DoxyLover May 1 '17 at 5:55

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    \$\begingroup\$ Because the electrons come from redox reactions, and the chemicals eventually deplete. \$\endgroup\$ – Ignacio Vazquez-Abrams Apr 30 '17 at 3:38
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    \$\begingroup\$ Or more descriptively, migrate from one side to the other. You'd have move those ions back on the starting side... ie, recharge the battery, if it's a chemistry/structure/enclosure that can tolerate that. \$\endgroup\$ – Chris Stratton Apr 30 '17 at 4:01
  • \$\begingroup\$ You will need some sort of energy source. Like mechanical energy, but then it's a generator, or thermal energy, e.g. Peltier effect. Or light, e.g. solar panel. However the closest to the concept would be fuel cell, e.g. if you can supply the consumable into the battery and remove the waste continuously, it will operate infinitely indefinitely. \$\endgroup\$ – user3528438 Apr 30 '17 at 4:23
  • \$\begingroup\$ All energy is converted from something. Mass is the most efficient source and even nuclear reactors are only 50% efficient until spent. \$\endgroup\$ – Sunnyskyguy EE75 Apr 30 '17 at 7:21
  • \$\begingroup\$ Electrons flow from cathode to anode. If you drop a brick from the roof of a house, it converts potential energy into kinetic energy and does work when it hits the floor. To repeat the test you must carry that brick to the roof again and, in doing so you put back energy into the brick. Please don't talk about infinite batteries. \$\endgroup\$ – Andy aka Apr 30 '17 at 10:01
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The problem is energy. Actually, for almost any physics problem, the answer is 'track the energy'.

In a battery, it's the potential energy of the chemicals, their ability to do work by changing to other chemicals with a different electronic arrangement and lower energy, that provides the energy to push charge round an external circuit. Once all the high potential energy chemicals have turned into low energy ones, no more work can be done.

If you want to keep pushing electrons round the circuit, re-use the charge that returns (so to speak), then you have to keep supplying energy. You could supply mechanical energy to a generator, thermal energy to a Peltier module, or chemical energy in the form of oxygen and a fuel to a fuel cell. These will all make 'infinite batteries' according to your definition, and the last is a chemical battery.

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The short answer is, chemistry. Those electrons don't go back to where they came from, they go to a different part of the battery, essentially. All the electrons that leave the battery are the product of a chemical reaction, and once the reagents are used up and the reaction's run to completion, you can't get any more out.

Chemical reactions of the reduction/oxidation (or 'redox') variety always involve the transfer of electrons. It's just that in this case, the battery's construction forces the electrons to take the long way around.

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  • \$\begingroup\$ Strangely enough, while the short name of the reaction is "redox", the full name is "oxidation-reduction". Bonkers, I know. \$\endgroup\$ – Ignacio Vazquez-Abrams Apr 30 '17 at 4:19
  • \$\begingroup\$ Well, I guess oxred just sounded too weird. \$\endgroup\$ – Hearth Apr 30 '17 at 4:47
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Short answer: Energy has to drive the flow of electrons in the first place. A different kind of energy, like chemical energy. Chemical energy is what pushes the electrons, imparting energy into the flow of electrons. That energy gets used up when we power something. The electrons flow back to the battery but the energy doesnt. The battery has a finite supply of energy in it stored in chemical form.

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  • \$\begingroup\$ Does the amount of energy usage depend on the load ? In other words, if I just short anode to cathode will the flow of electrons remain for longer time ? Is there an equation for how long the battery will last based on the load ? \$\endgroup\$ – Jibin Apr 30 '17 at 4:15
  • \$\begingroup\$ The battery has a finite amount of energy. Power is the rate at which energy is used; higher power means same energy in less time. Power is $P = V^2/R$, where $V$ is the battery voltage and $R$ is the resistance (load) you put between the terminals. If you short the terminals together that resistance will be near 0. That means power will be very high, and you will drain the batter very quickly. All that energy coming out at once is why batteries get hot and sometimes explode. \$\endgroup\$ – CogitoErgoCogitoSum Apr 30 '17 at 4:22
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All reaction in life generates heat, the heat is the result of used up energy correct? When electric charge runs though a wire a small amount of heat is being released this is because everything on earth has a small amount of resistance so even though electricity travels through conducting objects it still has to fight resistance that the object obtains.

That process generates heat which is energy lose. So when electricity travels out of a battery and through a conducting object small electric signals (heat) is being released into the air. This process essentially drains the battery. So basically you can't have an infinite battery unless you have some form of retaining the energy lost and reusing it.

This is my theory in a nutshell. If you want me to elaborate on your question please let me know.

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  • \$\begingroup\$ Why the down votes \$\endgroup\$ – Gova DEster Apr 30 '17 at 3:54
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    \$\begingroup\$ Heat is not "small electric signals", and while energy loss is why the battery is eventually drained, this is not answering the question. The question is not the sort that can be answered by just going to conservation of energy--the person clearly understands that their concept goes against conservation of energy and they want to understand what they have wrong. At least, that's my view of it. \$\endgroup\$ – Hearth Apr 30 '17 at 3:58
  • \$\begingroup\$ This doesn't describe the mechanism, but it's essentially accurate as thermodynamics is your basic "details don't matter, this is the inevitable result" legitimate way of debunking any proposed perpetual device. \$\endgroup\$ – Chris Stratton Apr 30 '17 at 4:03
  • \$\begingroup\$ I might be optimistic about the asker's knowledge, but this question sounded to me more like "my understanding suggests that this impossible situation might be possible. Obviously it isn't, but why isn't it?". \$\endgroup\$ – Hearth Apr 30 '17 at 4:07
  • \$\begingroup\$ This is your "theory"? Huh? \$\endgroup\$ – uint128_t Apr 30 '17 at 4:12

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