Sorry Redeasysport but you are reading something into it that is not there. It says to remove the negative terminal to prevent electrical damage to you or equipment due to a short w/ your equipment. It does not say you will damage anything by removing the positive terminal. Remove the negative instead of the positive for safety as stated before.

And the reason you can weld a wrench on the positive side and not the negative is:
When you short the negative to the car you are only pulling whatever current is drawn at the time w/ the battery hooked up. Usually everything is off except for minimal radio and ECM current and maybe a light. This is maybe 5 amps or so.
When you short the positive to the car (w/ the negative hooked up) you are pulling maximum current the battery can provide (650 cold cranking amps depending on your battery).

 

I just wanted to say that this has been a very "positive" experience reading this thread.

 

 

I believe that it was in fact Ben Franklin who made the "wrong" choice for naming + and - battery terminals. He was conducting his own electrical experiments in the early days of battery discovery and development, and he decided that the side with too many electrons was the + side. He assumed that they were flowing to the - side where there were too few electrons.

 

thanks for all the responses-now I believe I understand and will always disconnect the negative from now on.

 

Its a safety issue. The one thing you should never do is disconnect the battery leads when the car is running and then reconnect them as a way of checking the altenator.

Anytime I work on a car I disconnect the battery. Which lead it is doesn't really matter, but for safety I disconnect the - 1st.
As long as the - is still hooked up you can short out the +.

 

A general consensus is reached, but just to address the wrench-welding question in particular...

As many have stated, electrons DO flow from negative to positive and in the sense, think of electricity as traveling from the negative post of the battery, through the ground (car's metal surfaces) into each electrical component (through their attached ground) and back to the battery (eventually) through all those red/yellow/white/etc "power" wires from individual components.

Now when you take the negative side off FIRST you can touch the wrench to the frame and nothing will happen. There is no flow of electricity FROM the negative terminal. Kill the negative side connection, kill the flow of electricty.

If you leave the negative side of the battery on, by touching a wrench to the positive side and the frame, you are creating a direct, almost zero-resistance, ground from the negative post to the positive post. Electricity is "flowing" through all metal surfaces of the car, the "ground." Electricty will ALWAYS seek the path of least resistance, and by holding a solid, conductive wrench (like most wrenches are, opposed to expensive non-conductive) from the frame to the positive post, electricity will always choose to travel that path than though all the resistors, poor wire connection, path through your car's electrical system.

Hence why, remove the negative terminal first, positive second.

 

That's the reason I do it that way (remove the ground first), and the only valid reason I know of.

Larry
code5coupe

 

 

It goes on and on and on and on and on....
Come to think of it ... arent' those lyrics to an old song....