Why won't current flow between the negative positive terminals of two dry cell batteries?

Question

This means only that you connect the positive terminal of one battery with the negative terminal of another, with no other paths for current flow. It seems to me that a difference of potential should exist between the two.

Can someone please explain this to me?

Just so you know, dry cell battery means it uses dry chemicals to produce ions, not a dead battery.

I meant to say the negative "and" positive terminals.

Answer 1

Electrical current will only flow if there is a complete circuit.

Until you complete the circuit by connecting the remaining positive and negative terminals there is no flow.

You have technically doubled the potential energy (assuming the batteries are the same voltage) as connected in series, the voltages are additive (the current remains the same).

If you connected positive to positive and negative to negative, there would still be no flow until you completed the circuit, but in parallel, you will have left the voltage the same and doubled the potential current available.

Answer 2

There is no such thing as a negative-positive terminal.

Current does flow. The chemistry of the battery pushes the current to flow one way, but all you need is enough voltage, and a circuit and you can force current to go either direction in a battery. That does not necessarily "recharge" the battery, it just does a different chemical reaction than the preferred one.

Key word is circuit. If you have two different batteries, their chemical pumps cant squirt amps out without having a wire to pull amps in. No circuit, no electron flow (amps).

You could use some bizarre Lotka-Volterra system and switching to make a single pole "battery" that cycled. It would have to work like an electronic digery-doo. It might then be run to an h-bridge. It would be strange, and inefficient, and an EMI/RFI source, but it could work.

So maybe you could theoretically make a mono-terminal, but calling a negative-positive terminal would be a bad idea. You certainly cant buy it at a store today.

Answer 3

From the positive terminal of a cell, positive charge flows to its negative terminal via an external circuit. The positive charges on reaching the negative terminal go to the positive terminal inside the cell.

{Note that the actual motion of charge is due to electrons and is not as simple as I have stated. However there is nothing wrong if we considered it as above]


Therefore only if a circuit is closed, there is a current.

Before me answering your question, you answer my question.

In a single cell there is a negative terminal and a positive terminal. When the cell is not connected externally, it seems to me that a difference of potential should exist between the two and hence a current must be from the negative to positive of the cell inside the battery.

I hope you will answer I am wrong.

It is because; positive charges from positive terminal must flow externally to the negative terminal and not through inside the cell. Inside the cell the positive charges flow from negative to positive terminal.

When the cell is not connected externally, the positive terminal has high positive charges and negative terminal has high negative charges; and hence their potentials are positive and negative respectively.

Hope you now understand that a cell when not connected externally cannot send charges inside the cells.

Consider two cells are connected end to end in series as shown below
--╣--------------╣--
And they are not connected externally.

The high positive charges that are accumulated in the positive terminal on one cell are connected to the high negative charges that are accumulated in the other cell.

Immediately there will be re distribution of charges between the connected portion and the net potential depends upon the cells connected.

If the left one is 2v and the right one is 3v, after connection the right extreme becomes 5V, the positive terminal of the left cell and the negative terminal of right cell becomes 2 V.

Initially at the joining portion there was a potential difference and now it has come to a common voltage of 2V due to redistribution of charges and the extreme end has its potential raised to 5 v due to the redistribution of charges.

[You are correct in predicting that there must be some current. But it is a transient one and do not last longer].



Now the two cells are equivalent to a single cell of 5v and no current can flow through them inside unless connected externally.

I tried my best to explain though not completely to your satisfaction.

Answer 4

It sounds like you are having difficulty differentiating between Theory and Reality.
When dealing with electronics one must generalize somewhat to understand the concepts.
If you deal with reality to a minute degree you get bogged down in so many details you cannot handle it all.
If you generalize enough the general concepts and errors become understandable.
Stop confusing yourself with facts.
Understand the concepts and work on the errors later.

Answer 5

Current flow means the flowing of electrons. In dried cell, no electron left..