Hi all...
I am wondering about the potential (ha!) of having two batteries in parallel, then disconnecting ONE of the batteries NEGATIVE terminal..
This leaves two batteries connected to the load with their positive terminal, and only one connected to the load with the negative.

Since electrons travel from the negative terminal.. might they find their way to the positive terminals of BOTH batteries?

My intuition says no... but I'm not sure about the physics behind it.

Perhaps because battery 2 does not have it's neg terminal connected to the load... that somehow the voltage reference for the positive end of the battery is floating and rises such that its positive potential gone.

Thanks for your kind explanation for this condition!

 

Current always requires a complete (return) path so, disconnecting one lead of the battery is the same as disconnection both leads.
For current to flow in/out of one battery terminal an equal current must flow out/in of the other terminal.
So No current can flow into or out of the battery positive terminal with the negative terminal open.

If you look at how switches are connected to control power, they typically are in only one leg of the circuit, which stops all current flow.

 

Current always requires a complete (return) path so, disconnecting one lead of the battery is the same as disconnection both leads.
For current to flow in/out of one battery terminal an equal current must flow out/in of the other terminal.
So No current can flow into or out of the battery positive terminal with the negative terminal open.

If you look at how switches are connected to control power, they typically are in only one leg of the circuit, which stops all current flow.

Thank you... and of course I get that... but in this case there IS a path for electrons to flow... and a positive potential on two cells for the electrons to travel to. what PREVENTS the electrons from the first battery to also find the terminal of battery 2... essentially discharging the battery by filling electron holes?

I do get that the 2nd battery does not have a circuit, and I get the "rule"... but this is more a question about battery physics.

What keeps the electrons from traveling to the positive terminal of the second battery?

Analogy: two mountain lakes... not connected ... with a waterfall at lake 1 ... and two lakes at the base of the mountain, *connected*...

Both base lakes still fill (partially)... even though lake #2 has no waterfall of its own.

 

What keeps the electrons from traveling to the positive terminal of the second battery?

Because the net charge in the battery must stay constant.
So any significant charge into one terminal must be balanced by the same charge going out of the other terminal.
There may be a very slight charge going into one terminal to charge the stray battery capacitance when a voltage is applied to that terminal, but that stops as soon as the capacitor voltage reaches the applied voltage.
That charge has no effect on the battery chemistry.
Put a microammeter in the circuit and you will see that absolutely no charge is flowing.

 

Hi all...
I am wondering about the potential (ha!) of having two batteries in parallel, then disconnecting ONE of the batteries NEGATIVE terminal..
This leaves two batteries connected to the load with their positive terminal, and only one connected to the load with the negative.

Since electrons travel from the negative terminal.. might they find their way to the positive terminals of BOTH batteries?

My intuition says no... but I'm not sure about the physics behind it.

Perhaps because battery 2 does not have it's neg terminal connected to the load... that somehow the voltage reference for the positive end of the battery is floating and rises such that its positive potential gone.

Thanks for your kind explanation for this condition!

View attachment 184945

This blog post may help you understand things.

https://forum.allaboutcircuits.com/blog/a-battery-isnt-a-capacitor.588/

The equations may not render in your browser (particularly Chrome), but the text should tell you what you need to know.

Essentially what will happen is that the disconnected battery will move just enough electrons from the positive terminal to the negative terminal to establish the open-circuit voltage across the battery and then no more current will flow. The number of electrons required to do this is very small and this all happens over a period of time that is so short that it would take a pretty sophisticated measurement set up to even detect it.

 

This blog post may help you understand things.

https://forum.allaboutcircuits.com/blog/a-battery-isnt-a-capacitor.588/

The equations may not render in your browser (particularly Chrome), but the text should tell you what you need to know.

Essentially what will happen is that the disconnected battery will move just enough electrons from the positive terminal to the negative terminal to establish the open-circuit voltage across the battery and then no more current will flow. The number of electrons required to do this is very small and this all happens over a period of time that is so short that it would take a pretty sophisticated measurement set up to even detect it.

Thank you....

Though I believe electrons normally flow from the negative to the positive (which is important to the question).... but you seem to be saying that this flow is internal to the battery... for just an instant.

 

Ah! I have the *exact* misconception mentioned at the start of the article. Very enlightening... thank you!