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