Anonymous
Anonymous asked in Science & MathematicsEngineering · 2 months ago

Why does not either terminal of a battery when earthed (half) discharge the battery?

If you look at this question and answers you can see common belief that "Technically, the higher potential side of the battery is not higher/lower than earth.". But how can it be so if you look at how battery works, each terminal is either oxidized (lack of electrons) or reduced (excess of electrons), how in the world do you imagine either of those has no potential in respect to earth, earth is neutral and each terminal has a potential not only relative to other teminal, but to rest of the universe.

https://physics.stackexchange.com/questions/299199...

Update:

@Philomel's Are you stupid or just pretend to be? I am an el. engineer. Question remains perfectly solid.

Update 2:

Robert J "If there is no circuit, no electron path between the terminals" ofc, every child knows that is a general rule, BUT not really. We have two terminals, one is oxidized (lack of electrons) or reduced (excess of electrons), altho battery achieves this by chemical reaction, you can draw a parallel with a capacitor, if you take charged capacitor and earth each of the terminals, it may get PARTIALLY discharged since other side of the dielectric will keep the charge. Etc.

Update 3:

*each of the terminals meaning either of the terminals

Update 4:

There is also a question if capacitor can be charged by connecting a single terminal to the battery, no closed circuits again. Check the last answer. https://physics.stackexchange.com/questions/421473...

Update 5:

To go back to original question, consider terminals of a charged lead acid battery, lead plates on - side are full of extra electrons and those on + side are lacking same amount of electrons. Suppose we take the battery apart, we now have an equivalent of two charged Van Der Graaff domes, each plate carrying the same charge of opposite sign. They are carrying this charge independently from the other plate. Like Van Der Graaff dome, they are charged relative to the ambient, not other plate.

Update 6:

That is the point, that charged terminals can be separated and remain charged relative to the ambient, there is nothing mysterious about this.

Update 7:

Of course, if you just take a cap apart most electrons will remain stuck on the dielectric as demonstrated here https://www.youtube.com/watch?v=e2EWeOVCO5o

Youtube thumbnail

but the point remains clear, any charged object will seek to discharge (find balance) whether it is standalone or part of the system.

Update 8:

Here is more along same lines, second answer EDIT https://electronics.stackexchange.com/questions/33...

Update 9:

Reply to EDIT: you misunderstood, that is exactly what i'm saying and what links i linked say, no discharge. All i'm saying is that both battery and capacitor are made of two oppositely charged elements which, if standalone, WOULD discharge, much like dome of VDG.

Update 10:

oil field trash You seem to have trouble understanding English. My technical writing is quite impeccable, the question was would cap or a battery partially discharge by grounding either terminal, answer is it would not thus all clear.

Update 11:

That is, it would not to any significant extent.

Update 12:

oil field trash Just opened your profile, your field is gas pipes, lol. No wonder electrical language sounds like entabulator to you.

Update 13:

Look at these entabulators....hurts your head doesn't it..

XL= 2πfL

XC= -1/2πfC

Z = sqrt(R² + (Xc - Xl)²)

F = 1/2π√LC

C=1(L*(2*pi*Fr)^2)

V × A = J/C × C/s = J/s = Watt

electric energy E = IVt and E = (V²/R)t

1F = 1C / 1V 

C = Q / V and C = kA/d

E = F / Q   (N/C or V/m)

F = qE + qv x B

....

3 Answers

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  • 2 months ago
    Favourite answer

    Current flow requires a _circuit_ 

    If there is no circuit, no electron path between the terminals, there cannot be any current flow.

    It's one of the most fundamental principles of electricity / electronics:

    In a series circuit, the current is equal at all points.

    The two terminals of the battery & the battery itself are part of a series circuit (when connected to something that draws current).

    Any interruption, at either terminal or elsewhere, means no current at that point,

    ***so no current anywhere else***.

    It makes no difference where in that circuit the path is interrupted, of it's interrupted multiple places or just once.

    Static voltages are a different thing - but a static voltage is present without current flow, so no discharging of the battery.

    eg. If you ground the negative, the other terminal will be positive relative to ground; ground the positive, and the other terminal is negative relative to ground.

    Edit: 

    A capacitor, if you connect a terminal to ground, will lose a small amount of energy to the parasitic capacitor formed between the bulk of its own body and ground. There will be a momentary current flow while that equalises, then none.

    You would have to keep swapping terminals to further discharge the cap.

    The same would happen with a battery; you charge (or change the charge) on the capacitance between the battery bulk metalwork etc. and ground.

    A momentary small current, then none. 

    It does not discharge the battery as a capacitor does not pass DC, and a battery stores orders of magnitude more energy than any normal capacitor.

    (If that stray capacitance was eg. 0.1uF, to charge to 12V would take just 7.2 micro joules. Compare that to the power storage of a battery; you mention a lead acid type, so assuming a 12V car battery, eg. 80AH:

    80 x 3600 x 12 = 3.46 million joules...

    Swap the ground connection between terminals roughly a million million times and you may somewhat flatten it by continuously reverse recharging the stray capacitance).

    And finally:

    As it's a demonstrable fact that batteries do not self-discharge any faster if one terminal is grounded [and the other not connected to anything], any hypothesis that says they should discharge under those conditions is proven wrong - and can be dismissed out of hand as obviously in error..

  • 2 months ago

    You seem to be having a problem wording your question(s) so everyone can understand. I have read it with all your addictions and it reminds me of a well know video about an entabulator. You need to try to improve your technical writing so it doesn't sound like the entabulator.

  • 2 months ago

    You don't understand how electricity works or doesn't work. Go to a library and read Electricity for Dummies.

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