does the car battery circuit complete if we disconnect the negative terminal from car's frame?

Question

I assume that the car's frame is zero voltage, so there's a potential difference between the battery and the frame, right?. Does that make the current goes through the appliance to the frame? I can't imagine that the current will return the negative terminal since the frame is too big.

May be my bad English makes some one misunderstood, so I need to say it in another way. I wanted to say that could the circuit be completed if we connected the positive terminal to the frame without the battery's negative terminal connected to ground (frame)?.
I was wondering that because I thought there may be a potential different from the positive terminal of the battery and the frame (without battery's negative terminal grounded)
I don't have a car though :D

Answer 1

The negative terminal of the car battery is to ground the battery so the engine and occupants don't get shocked! you do have to have it connected as well as the positive for the circuit to be complete! If jumping the car it's best to have the grounding wire connected to the car frame so it is grounded else where and won't damage the battery!

Answer 2

The frame of the car is used as a very heavy wire. It lets you run just one expensive wire to the starter and use the frame for the return path for the current. You could just as well connect the positive terminal to the frame INSTEAD of the negative, and some vehicles used to do that. It's simply a convention. But if you connect BOTH battery terminals to the frame, you provide a short circuit, which will promptly destroy the battery and melt the wires.

Voltage measures a difference in electric potential. You can define any single point as the zero point for voltage.

When jump-starting a car with another battery, it is best to make the final connection to the frame rather than at the battery. The only reason is to reduce the chance that the spark will ignite any hydrogen gas released from the battery. With modern battery chemistry and seals, that is less of a concern.

Answer 3

The size of the frame is meaningless to the return of current flow to the battery. Where is you get that idea from?
So far as jumping the battery is concerned, there is no problem connecting the aiding battery directly to the gaining battery. So far as the other part of your question goes, technically, there is a very small potential difference between the negative terminal of the battery, and vehicle body ground. It's something on the order of 0.01 volts, or less. This can, however, be used to find the current being drawn from the battery during a start of the vehicle, if, and only IF you know the resistance of the ground strap between the battery negative terminal, and the body of the vehicle.

Answer 4

That's what happens, though. Auto manufacturers make use of the fact that car frames are conductive to eliminate what would otherwise be 50% of the wiring.

Answer 5

No.