Positive or Negative

[Gunsrunner]

Hello,
Just fitted a battery isolation which.
In the manual bombardier recommends to disconnect the Negative terminal first.
But i have read forum,s where people have fitted isolation to the positive terminal.
I would like to know why does it make any difference which one is disconnected first?

 

[kustomkarl]

If you disconnect the positive first it will spark and could cause a fire. If you disconnect the negative it won't spark...it's a safety idea.
Karl

 

[seadoosnipe]

pow!

And if you ever do like me, take off the positive first and that arc shoots across and hits that negative cable, then you'll find out like I did to see what it looks like for a battery to blow up!........
It scared me more than it hurt me, but I was lucky......

 

[kustomkarl]

That's not a good thing Louis...plus it could have ignited the gas fumes in the engine compartment...you wouldn't have to worry about the POW, you wouldn't hear or see it. Negative first...rule of thumb.

 

[seadoosnipe]

That was a learned lesson...

Yeah, that was a learned lesson. It actually happened when I was about 18. Sometime, we learn the hard way. I haven't done that since. I was very lucky. That acid blew everywhere, but none got in my eyes, thankfully....

 

[kustomkarl]

When I learned that in Kawasaki Tech training, in Edison N.J where I attended a 2 stroke and 4 stroke theory school for 2 weeks. It was required by the shop I worked in part time. I was 16 at the time.
Karl

 

[manicmechanic]

What a mess!....

Battery acid burns if you get it on you. Sulfuric acid is a really strong base and should be careful around water due to the fumes that can be released.

 

[kustomkarl]

Got to be careful of open flames and sparks as it can explode also...

 

[manicmechanic]

Explosive?

Due to the sulfuric acid having a violent reaction to water, the vapor emitted can be explosive. But the cocentration is normally to weak for an explosion to take place, unless your in a confined space.
If your inside, leave a window open. The ambient air drafting through should be adequate to keep concentrations low.

 

[kustomkarl]

It's not just about the acid concentration, but the gas fumes with a sparking positive connection could set it off...that's why we use blowers on Jet boats and in closed compartments.

 

[seadoosnipe]

Hydrogen

If I remember my chemistry right Karl, I think what he's pointing out is that the sulfuric acid, when mixed with water, causes a gas vapor that can be explosive. The exposive component is hydrogen. But even hydrogen is only explosive in concentrations.
At the plant I work at, we work with sulfuric acid on a regular basis. I've seen a tank of water catch on fire, just because the sulfuric acid that was introduced to control the pH value, created hydrogen gas and it caught fire.
At any rate, an arc flash from the positive to the negative post will definitly pose the risk of explosion.

 

[Dennis]

Battery Connection Sparks

Hi Guys,
Let's all keep in mind that EITHER battery cable can cause a spark when being connected to the battery if it's the last one being connected and there is a load on the circuit.
DAWG

 

[kustomkarl]

The chance of fire or explosion is higher with gas fumes than from the battery itself. The resistiance from a batteries positve is less than the negitive even under load, so it is more likely to generate a higher flash from the positive than the negative. Yes, it could flash from the negitive...but it WILL flash from the positive,load or not.

 

[seadoosnipe]

That is a fact....

:agree: I agree with you Karl.....If you do a google on that procedure, it also states negative first.