Battery disconnects at car wrecks

[K31Kfd]

I am looking for any information from the people in the field about disconnecting the battery. Our dept disconnects the Positive side first. Is this wrong? I have heard that diconnecting the positive can set off some air bags. Has anyone got any suggestions or answers? Thanks

[Pyro128]

Every time I attended a lesson about extrication they taught to disconnect the NEGATIVE first...

I think this has something to do with the connection with the cars body...

[Zmagrescue]

Fairly simple reasoning here. If your craftsman wrench is on the positive post and the handle bumps against the fender or any other metal you will get a spark. Positive to negative equals short. However a cross connection between the negative post and body equals nothing. My rply, always go negative first.

Zmag

[MetalMedic]

ZMag hit the nail squarly on the head. We always go for the negative side first, unless it is somehow obstructed leaving the positive as the only one we can get to immediately. Even then, we will disconnect the negative as soon as we can access it.

[ROBlenis]

Seems like everyone's on the right track here. The negative side is always the way to go. The reason is that the negative, or ground of the battery is bolted directly to the frame or the body of the car. The only way to prevent accidental electrial discharge from the battery is to eliminate the ground connection. <img src="biggrin.gif" border="0">

[K31Kfd]

Thanks for the info. I will pass it on to those who have said different.

[firenresq77]

Personally, I prefer to cut out a small section of the negative cable. I do it because I don't want to disconnect the cable only to have it move and ground out on something else. I usually cut out a section just long enough so that the 2 ends will not touch.

[engine117]

I like firenresq77's idea. Although it has never happened to me, it is possible for something to happen that would cause a spark by the ground flopping around. either way though, definitely negative first.

[todd nelson]

I agree with ZMag, negative first and you should always try to cut the wires in two places so the cables have no chance in reconnecting.

[LYFDChief]

My department tries to do the same - cut a section of negative cable out first to avoid any chance of an accidental re-connection.

[rmoore]

The November '01 University of Extrication article took an interesting look as the problem of 'partial' battery shutdown. The bottom line of that article is that the negative(ground) cable(s) should be cut or disconnected first. This action, however, must be followed with cutting or disconnecting the hot (positive) cable(s) as well.

In the article, there are several case study examples of real-world cases where the battery kept current flowing through the vehicle even though the negative cable was disconnected or the battery severely damaged in a crash.

In addition, if your department's battery policy is to cut cables, "double-cut" the cable. Take away that one inch of cable with a double cut so that the fresh ends will never be able to make contact.

Ron Moore

[lutan1]

I don't know how much your cars differ from ours, but we ALWAYS go for the earther battery terminal first.

On some cars, they have a +ive earthm and others are a -ive earth. (Check out all your dealers, some manufacturers are still making a +ive earth, whilst others are doing -ive earth. We can't just assume they're all the same)

I agree with others about the risk of shorting whilst disconnecting, thats why we go for the earthed terminal.

With regards to disconnection versus cutting a section of lead out, we always disconnect on the chance that for some unforseen reason we may need to reconnect the battery to get power back to the car, such as for electric seats, etc.

Our unit is now placing the disconnection of the battery terminals a little lower on the priority list until we are ready to begin the extrication so as we can move seats, windows, etc. before we begin metal movement. <img src="smile.gif" border="0">

[Jim Greene]

Yes everyone has the same idea. Take the neg. first then the pos. next. Just remember to still use air bag safety because some vehicles will take a while to discharge the air bag sensor unit.

[noneya]

I agree the negative goes first....

Remember to check with the folks doing extracation they made need that power to move a seat for example.

[tfd603]

Remember if you cut the negative to cut it twice to keep it from coming back together. What I like to do if possible is disconnect the positive also,to be sure. The negative is the first to go tho. Also remember that if dealing with airbags that doesnt guarantee a deployment of the SRS system.

God Bless America and those who protect it.