Right, so this is probably a pretty noob question, but I'm really interested so anyway…
Suppose I disconnected the negative terminal on my cars lead-acid battery. Instead I grounded the frame of the car to a good ground. The voltage difference is now 12V again and my car should work, right? The current would flow from the positive terminal to ground. Would the battery still work, ie. would the chemical reaction still take place, since there is nothing connected to the negative terminal?
What if I did it the other way around and connected an outside 12V DC source to the car, but left the negative terminal connected to the car with no other ground.
I hope my question makes sense haha. I don't know enough about batteries and electrical engineering to understand what would happen
Best Answer
If you leave either terminal of the battery unconnected, no current will flow from it. For current to flow there must be a complete loop, or circuit, and the resistance along the path of the loop and the voltage(pressure) applied will determine how much current will flow.
Note that in electrical and electronics it is not uncommon for things to be referred to as ground that are not actually grounded, and are simply a dedicated return path for current. For this reason, the new convention in electrical is to refer to things that are directly connected to ground up to the point the connection diverges(IE a ground rod pounded directly into conductive earth, the wire attached to it up to the first enclosure in which it splits are ground. Anything past that point in green or bare copper is "bonding")
Your question seems to stem partly from the idea that the "ground" on your car is related in some way to the "ground" that is the earth.
The electrons that flow out of the battery must be replaced by the electrons flowing into it. A battery does not supply you with electrons, it provides you with the emf(voltage/pressure) to make them flow. The electrons are already present in the materials the electrons will flow through(conductors). If you think of a copper wire as a pipe for electrons, you must think of it as a pipe that is already completely full of them.