Batteries and the idea of a "completed" circuit.
Batteries and the idea of a "completed" circuit.
(OP)
Howdie. It has been some years since I studied electronics (I have very little practical experience with it), but back then I had a question which seemed not to have an answer. But someone posed the same situation and now the question is back. Simply put, it is this:
Suppose you have a battery charged to 12V. If I connect a wire without a resistor across the leads, current will flow rapidly and the battery will overheat and might get destroyed, because I have completed the circuit with minimal resistance. Now if I take that same battery charged to 12V and instead of shorting across the terminals, I instead connect the negative terminal to a huge steel ground plate while leaving the positive terminal open, my sense is that no current will flow into the plate or hardly any since there is not a completed circuit. My reasoning is that the electrons in the battery are still attracted to that 12V potential inside the battery, and connecting the negative terminal to some other external ground does not attract the electrons any stronger than the potential inside the battery does. I imagine that the only possibilities are that the electrons will not get all bunched up trying to cross the battery's internal potential, and essentially "hating" each other will try to get as far from each other as the battery's design will allow. PERHAPS, a little current will flow out to the big metal plate only due to the electrons' mutual repulsion.
Is this correct, or am I getting it all wrong? Do the electrons see the huge steel plate as the other side of the battery?
Thanks for any responses!
Suppose you have a battery charged to 12V. If I connect a wire without a resistor across the leads, current will flow rapidly and the battery will overheat and might get destroyed, because I have completed the circuit with minimal resistance. Now if I take that same battery charged to 12V and instead of shorting across the terminals, I instead connect the negative terminal to a huge steel ground plate while leaving the positive terminal open, my sense is that no current will flow into the plate or hardly any since there is not a completed circuit. My reasoning is that the electrons in the battery are still attracted to that 12V potential inside the battery, and connecting the negative terminal to some other external ground does not attract the electrons any stronger than the potential inside the battery does. I imagine that the only possibilities are that the electrons will not get all bunched up trying to cross the battery's internal potential, and essentially "hating" each other will try to get as far from each other as the battery's design will allow. PERHAPS, a little current will flow out to the big metal plate only due to the electrons' mutual repulsion.
Is this correct, or am I getting it all wrong? Do the electrons see the huge steel plate as the other side of the battery?
Thanks for any responses!





RE: Batteries and the idea of a "completed" circuit.
Bill
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"Why not the best?"
Jimmy Carter
RE: Batteries and the idea of a "completed" circuit.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Batteries and the idea of a "completed" circuit.
Anyway...I should have bet my old boss $100.00!
Thanks again.
RE: Batteries and the idea of a "completed" circuit.
RE: Batteries and the idea of a "completed" circuit.
Just diden't know if that was important to you.
RE: Batteries and the idea of a "completed" circuit.
You mean (exactly) like any parked car?
"...cause rusting of the metal plate. But all this takes time, like weeks."
Weeks? See above. Seems a bit pessamistic.
RE: Batteries and the idea of a "completed" circuit.
RE: Batteries and the idea of a "completed" circuit.
And yes I am a pessimest a good pert of the time (it keeps me employed). Just like we don't need a military (unless we have a war). [I know this is a bad example, because I don't agree. But it is an example.]
There is a whole art to rust prevention, of which I know very little (it's the guys down the hall that know about it).
But connect a steel ground to a copper ground and you will have problems in the future. There's no power source but it happens.
RE: Batteries and the idea of a "completed" circuit.
The way I see it, we are talking about galvanic cells. But without an electrolyte or conductor to connect the steel plate to the positive terminal, there is no connection and thus no (accelerated) reaction.
BrianE22: no, the entire plate will be at the same potential, which is the same potential as the capacitor negative (and in this example, 12V less than the capacitor positive).
RE: Batteries and the idea of a "completed" circuit.
RE: Batteries and the idea of a "completed" circuit.
The question maybe over what period of time are we interested in.
So like so many times, the answer is: It depends on the details.
Never put your name on an estimate, unless you are willing to defend it as a fact.
RE: Batteries and the idea of a "completed" circuit.
Gunnar Englund
www.gke.org
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Half full - Half empty? I don't mind. It's what in it that counts.