Anonymous asked in Cars & TransportationMaintenance & Repairs · 10 months ago

What happens when you mix up the positive and negative battery cables?

Then try to jump a car?

23 Answers

  • Bort
    Lv 6
    10 months ago

    The cables will arc on the battery and several things *could* happen, what's gauranteed is a light show of sparks. Now these things *could* happen, it doesn't mean they will. It's best not to take the risk of any of this happening and make sure you connect positive to positive and negative to negative:

    1. KABOOM! It could cause one of or both of the batteries to explode sending acid water everywhere. If that stuff gets in someones eyes it's has potential of causing blindness. And don't forget about the shrapnel it will be throwing.

    2. It not could but it's going to arc and throw sparks. This could destroy one of or both batteries shorting them out rendering them both dead and needing replaced.

    3. Again, it's very likely going to spark. The spark could possibly weld the cable ends to the battery terminals and this can happen very extremely quickly. Also = dead batteries and possibly fry some of the electrical systems including the computers in both vehicles.

    There are 3 things that could happen. There's more possibilities of what could happen. I hope that's enough info so that if you're ever jumping a car battery you make sure you connect + to + and - to -

  • hart
    Lv 6
    10 months ago

    you will burn all electronics

    what ever is switched on

  • 10 months ago

    In the days of carbureted engines, you would immediately burn through a fusible link on the firewall or near the starter motor. Somewhat easy repair but would leave you stranded unless you had your tools and a replacement fusible link in the trunk. 

    In modern cars, it often destroys a component inside the ECM or "computer box" that runs the engine in closed loop. (Hot engine) If that doesn't occur, then you may get lucky and burn through one of the high amp (200 AMP+) fuses in the fuse box under the hood or possibly dashboard. 

    Either way, it boogers up a relatively easy procedure and leads to costly repairs and down time. 

  • 10 months ago

    we ought to get  almost instant warming of wires. possible smoke and major component damage. if we have smart start  technology etc we will get  even more  costs to fix. 

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  • Anonymous
    10 months ago

    Expensive fireworks you don't want.

  • Anonymous
    10 months ago

    Instantly....I did say INSTANTLY fry the alternator.  There is a $400 additional cost you did not need.(per alternator)

    .   Mixing up is hard to do because the battery posts are different sizes so the battery clamps won't fit as one is bigger than the other.

    .   As you are jump starting cars, that would cost 2 alternators as both cars suffer.   And the battery sparks like you were ARC welding - so LOTS because the battery does not like it either. 

    Which you should notice right away.  

    It happens especially with jumper cables that are not yours.  It is only AFTER THAT YOU FIND OUT THAT ON ONE END IT HAS RED BLACK AND ON THE OTHER END IT HAS BLACK RED.  So your fault not to make sure the red clamp wire is red at both ends.  So the black is black at both ends so the mistake NEVER WILL HAPPEN AGAIN.  Fortunately, I had a generator not an alternator.  Generators can handle mix ups without going for a chitter.

  • 10 months ago

    depending on the car, there may not be a good outcome

  • 10 months ago

    I did that in 1969 and the battery exploded. Batteries haven't changed in 50 years.

  • 10 months ago

    Scare the **** out of yourself for starters!

    Then you wonder about damage to the vehicle.

    There is a fusible link in the engine compartment fuse box that needs to be checked to find out if it blew to protect the electrical modules and the PCM and alternator. Fusible links are the larger fuses.

    If you had the dead vehicle's ignition turned on when you hooked the jumper cable backwards there's a good chance you fried the PCM and other modules. Big $$$ if you did that.

    Source(s): Mitsubishi Master Tech
  • Tommy
    Lv 5
    10 months ago

    Nothing good. There a good chance the battery will blow.

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