When you connect two batteries in series, why doesn't the middle short?
When you connect two batteries in series, why doesn't the middle short? The connection between the positive terminal on one battery and the negative terminal on the other battery has no load, so shouldn't it be shorted? 








simulate this circuit &ndash; Schematic created using CircuitLab

Figure 1. A short-circuit is usually defined as an unintended bypass of the intended circuit. Here the intended circuit is the loop consisting of the battery and lamp. The short-circuit is bypassing the lamp and providing a "short-cut" between the terminals of the battery. If the resistance is low then high currents will flow.







simulate this circuit

Figure 2. (a) No short-circuit occurs when the batteries are properly connected in series. (b) Attempted series-connection of two grounded batteries would result in a short-circuit as the current could flow through the ground connection as indicated by the red arrow. BAT3 is short-circuited while BAT4 is not.


  But I don't notice heat or explosions or anything like that when I connect batteries in series.


That's because no current is flowing as in Figure 2a.



From the comments:


  How come in Figure 2a there is no current flowing between the positive terminal of BAT1 and the negative terminal of BAT2. 


Because there is no closed circuit.


  I thought BAT1's positive terminal has a deficiency of electrons while BAT2's negative terminal has an excess of electrons. 


No, the net charge in a battery is zero! There is no surplus or missing charge at either terminal.


  So shouldn't the excess electrons in BAT2 flow towards the positive terminal of BAT1, thus creating a current?


Current can only flow when there is a circuit. As shown in Figure 1 the circuit is open so no current can flow.




  I thought a battery separates itself into two sides, one positive and one negative, with a barrier in between.


If that were true then batteries suspended by a thread around their middles would all line up due to electrostatic attraction. (They don't.)