You say there are no dumb questions.......

[babytiger]

So here you go.... What is the difference in disconnecting the negative battery cable as opposed to disconnecting the positive battery cable?
Wouldn't unhooking either accomplish the same thing? In reference to mods on our cars.
thanks in advance

[Iron Lung Jimmy]

By unhooking just the negative cable you risk accidentally grounding to something else... so now everything is alive again. Unhook the positive cable and there is no chance of that.

[babytiger]

Originally Posted by Iron Lung Jimmy

By unhooking just the negative cable you risk accidentally grounding to something else... so now everything is alive again. Unhook the positive cable and there is no chance of that.

I'm not arguing your point, but why do most instructions for things say "disconnect negative cable"?

[10forty2]

By disconnecting the negative cable, you don't stand the risk of striking a ground with your metal wrench or pliers while touching the positive post, thereby causing an arc and/or shorting out electronics and possibly even starting a fire.

[twmotox]

It honestly makes no difference but I think the reason is so that when you are removing the cable if you use the negative side it wont matter if you strike your wrench on something

[bhall82]

Originally Posted by 10forty2

By disconnecting the negative cable, you don't stand the risk of striking a ground with your metal wrench or pliers while touching the positive post, thereby causing an arc and/or shorting out electronics and possibly even starting a fire.

Originally Posted by twmotox

It honestly makes no difference but I think the reason is so that when you are removing the cable if you use the negative side it wont matter if you strike your wrench on something

THIS

[Iron Lung Jimmy]

Oh, I kind of misunderstood your question.

Beats me .

I always disconnect both. I never even notice they tell you just disconnect the negative. If you do just disconnect the negative, wrap it in a rag or something so it can't end up touching a body panel or trunk floor or whatever.

[MLL67RSSS]

Originally Posted by twmotox

It honestly makes no difference but I think the reason is so that when you are removing the cable if you use the negative side it wont matter if you strike your wrench on something

It makes a HUGE difference! If the neg is still attached and you have a tool on the positive side if you touch any grounded metal while the tool is touching the positive lead you will be putting a dead short across the battery and it will blow/melt the end of the tool off and scare the ever lovin' XXXX out of you. ALWAYS remove the negative first so if you slip on the positive no circuit can be completed and no tools melted or battery fires/explosions started.

Once watched a guy instantly melt off half of the end of a pry-bar this way, molten metal and sparks shooting everywhere. Whole lot of current in a car battery!

http://askville.amazon.com/dangerous...uestId=4217899

"You mentioned the danger of a wrench or other short circuit across the battery terminals. This is a real danger. Car batteries have tremendous current capabilities, and a short circuit can produce a huge, white-hot electric arc. It's hot enough to melt steel and inflict severe burns, and to set the car on fire. Always use caution when working with metal tools around the battery. If you must work on it, disconnect the negative (ground) cable first, so that the positive terminal no longer has potential to the vehicle ground. It is not dangerous to touch the positive terminal with your bare skin, because 12V is not a hazardous voltage. But it is made of lead, which is not good to touch if you can avoid it."

[MLL67RSSS]

Originally Posted by Iron Lung Jimmy

If you do just disconnect the negative, wrap it in a rag or something so it can't end up touching a body panel or trunk floor or whatever.

The negative battery cable is already bolted to the engine block and all sheetmetal in the car. Won't hurt if it touches anything since it's already connected electrically to them.

[Caswell239]

You unbolt the negative because web you go it with a positive, there's a little spark when it makes contact which could cause the battery to explode because the gasses it vents off. Our cars having it in the trunk have to have the battery vented to outside so there won't be any gasses just laying around as compared to a vehicle with one under the hood


Sent from my iPhone using Tapat

[Scalded Dog]

Agreeing with most on here, that it mostly has to do with the act of removal of ONE terminal clamp: While doing so, the wrench might touch something else, and performing the clamp removal on the negative terminal poses only the very slight risk of touching the positive terminal. If you are disconnecting the positive terminal first, touching just about anything else on the car will cause the fireworks. (And the fireworks is what causes battery explosions, if there is any leakage of gasses from the battery (sparks are the ignition source). I've seen it happen a couple of times, and an exploding car battery ain't no joke... I saw shrapnel bash the inside of a Mercedes hood out to the point of being unrepairable. Just the idea of acid flying everywhere is scary, too... had a battery explode in a John Deere lawnmower one day, and in addition to the shell shock, it destroyed all of the clothing I was wearing... ate holes through everything).

[CamaroSkooter]

You're better off removing the negative terminal, then removing the positive terminal, then removing the battery from the car and setting it a safe distance (50-ish feet) away from whatever you plan on working on.

Better safe than sorry

Said with a not-so-straight face...

[malave7567]

a few years ago, I made the mistake of trying to take the positive off first (not thinking), and my wrench just barely tapped my aluminum radiator. Nothing horrible happened because it was an extremely slight tap. But it scared the **** out of me, jolted my hand a bit. And I had to explain why there was a discolored little spot on the radiator when I sold the car. Learned my lesson to always keep my head in the game when working with electricity...

[paul84043]

I left a small silver ring welded to the engine block of a 1980 Chevy Monza that I was attempting to adjust the distributor on...got the wrench across the wrong thing..
Yeah, scares the s#!t out of you and burns like hell.

Had to reach in with the other hand and cut the ring with side cutters...that was fun.