Southpark, thanks for the comment:
"For example, if pin 7 goes high (voltage) with respect to 'gnd', then the upper transistor turns 'on', right? Which basically connects the + terminal of battery #2 to the - terminal of battery #2 via the 'C-E' route."
Yes, but that is obvious (I know you probably wont like me saying that). The important bit is it shorting to "damaging the battery"? - e.g perhaps (1) passing through the transistor reduces the current "enough" and/or (2) the voltage passing through the transistor combined together (note batteries 2 and 3 are in parallel through the transistors) may even possibly reduce the shortage effect because they are completing. Yes I've probably got all this terminology wrong - the point is maybe the "short" circuit doesn't really matter here. But I'm not sure yet...
There exist people who are all too willing to throw out all traditional lines of thought, , and on the other side people who are engrossed in traditional methods they can't see beyond into new possibilities. Yes, I may be wrong in this instance but would like to investigate. Hope there's nothing "wrong" in that!
Most welcome Caleb.
The first thing to do is to read up on (ie. google) things like 'dangers of short circuiting battery'. Even if the danger situation were 'ignored' ...... then there will be other shortfalls. Let's consider everything.
Short circuiting a battery (for batteries having no inbuilt protection features) basically allows the energy in it to be drained relatively fast ...... as in could be within seconds ....... and the battery and/or the wire could get very hot due to the relatively high current flowing through the wires ...... could result in burning of wires, and burning of battery, explosions. People getting hurt. Homes getting burned right out etc.
And ---- for batteries that have inbuilt protection against shorts ---- that's if they have such protection in them (some batteries) ----- a short circuit condition will mean the battery and system operating away from normal desired conditions ..... which will mean the system is not going to perform as expected (or as desired). When a battery becomes shorted, and if that battery is meant to power the system (circuit), then the system won't work ----- due to the short circuit, because the battery won't be able to carry out its intended function ---- as in to supply power to the circuit/system.
And in your case ------ you mention that the motor still works. But with that particular wiring diagram you showed, it is difficult or impossible to believe that your motor actually works with that particular wiring you have in the opening post. But ----- let's just say that your motor does turn. The prediction would then be the batteries will have their stored energy depleted real quick. But even then ........ the safety recommendation is to not use that circuit you showed in the opening post ..... because seriously, as raschemmel pointed out somewhere in his/her post, things could end badly.
And one teaching here is ...... a short circuited battery will mean that the bulk of the current will flow through the short circuit and not much current will flow through the rest of the stuff (ie. devices, components etc) that the battery would normally supply current to. And if not much current flows into your circuit (such as your motor), then the motor (or your circuit) is just not going to work. But ----- not working is fine. The bad thing is that a fire or exploding battery can cause some nasty damage to people and property. So be real careful when working with electronics. Make sure to get some fundamentals (circuit theory) under the belt first. Look after yourself and others and property first. Very important.