1. #1
    Junior Member

    Join Date
    Sep 2001
    Location
    Hobbs, New Mexico
    Posts
    24

    Post Battery disconnects at car wrecks

    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

  2. #2
    Member

    Join Date
    Oct 2001
    Location
    Aalst, Belgium (Europe)
    Posts
    35

    Post

    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...

  3. #3
    Forum Member

    Join Date
    Jan 1999
    Location
    Glen Rock, Pa
    Posts
    126

    Post

    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

  4. #4
    Forum Member
    MetalMedic's Avatar
    Join Date
    Dec 1999
    Location
    The Home of Smucker's Jelly
    Posts
    1,266

    Post

    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.
    Richard Nester
    Orrville (OH) Fire Dept.

    "People don't care what you know... until they know that you care." - Scott Bolleter

  5. #5
    Junior Member

    Join Date
    Nov 2001
    Location
    York, Maine
    Posts
    2

    Smile

    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">
    Crasher

  6. #6
    Junior Member

    Join Date
    Sep 2001
    Location
    Hobbs, New Mexico
    Posts
    24

    Post

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

  7. #7
    Forum Member
    firenresq77's Avatar
    Join Date
    Oct 2000
    Location
    Northwest Ohio
    Posts
    5,213

    Post

    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.
    The comments made by me are my opinions only. They DO NOT reflect the opinions of my employer(s). If you have an issue with something I may say, take it up with me, either by posting in the forums, emailing me through my profile, or PMing me through my profile.
    We are all adults so there is no need to act like a child........
    IACOJ

  8. #8
    Member

    Join Date
    Oct 2001
    Location
    Greensburg
    Posts
    78

    Post

    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.

  9. #9
    Junior Member

    Join Date
    Nov 2001
    Location
    Pembroke Pines Florida
    Posts
    11

    Cool

    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.

  10. #10
    Junior Member

    Join Date
    Nov 2001
    Location
    Johnstown, Pennsylvania
    Posts
    8

    Post

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

  11. #11
    MembersZone Subscriber
    rmoore's Avatar
    Join Date
    Dec 1998
    Location
    Plano, Texas
    Posts
    815

    Post

    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
    Ron Moore, Forum Moderator
    www.universityofextrication.com

  12. #12
    FIGJAM
    lutan1's Avatar
    Join Date
    Jan 2001
    Location
    I come from The Land Down Under!
    Posts
    1,833

    Post

    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">
    Luke

  13. #13
    Junior Member

    Join Date
    Feb 1999
    Location
    West Henrietta N.Y. U.S.A
    Posts
    6

    Post

    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.

  14. #14
    Junior Member

    Join Date
    Dec 2001
    Location
    Pennsylvania
    Posts
    2

    Post

    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.

  15. #15
    Junior Member

    Join Date
    Jan 2001
    Location
    Virginia
    Posts
    18

    Post

    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.

  16. #16
    MembersZone Subscriber
    AC1503's Avatar
    Join Date
    May 1999
    Location
    Indiana
    Posts
    325

    Post

    Are there any positive ground vehicles made or sold in the USA. Like those which Lutan spoke of in Australia?

    Hey Lutan, do ya'll use Direct Current electricity for normal household supply or Alternating Current like we do? Is your household current negative or positive ground?

  17. #17
    Junior Member

    Join Date
    Jun 2001
    Location
    Carlsbad, CA. U.S.A.
    Posts
    9

    Post

    Hello and have a great new year everyone. I have always taken out the negative first. Note: The older 1955 G.M.C. pick up was positive ground. Some vehicles electrial systems are completly isolated and not grounded to any part of the vehicle. When we find it we will use it to our advantage before illiminating it.

  18. #18
    FIGJAM
    lutan1's Avatar
    Join Date
    Jan 2001
    Location
    I come from The Land Down Under!
    Posts
    1,833

    Post

    In reply to "DD", I know of that the latest BMW to come into Australia is a +ive ground, so this obviously blows out the theory of always disconnecting the -ive first....<br />The recommendations made by Mercedes Benz is to disconnect the -ive first, then the +ive, THEN to insulate both leads to prevent any possible shorts.....

    With regards to household supply, we run AC, but I'm not too sure about the grounding. I believe the older houses were a positive ground, but newer installations are negative ground- not sure. (Whoever reads this, don't take it as gospel- check with the relevant authority!)<br /> <img src="smile.gif" border="0">
    Luke

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts

Log in

Click here to log in or register