Jump Start Your Car Safely

April 4, 2013

How to Jump Start a Car Safely

Even though your car battery has faithfully served you for several years, one day it may fail.  This frequently happens when winter comes because the stress of cranking an old engine with thickened motor oil requires a lot of energy.  It’s pretty distressing to find out that your car won’t start on a cold winter morning.

The first source of help in such a situation is someone who can jump start your car with cables attached to their function running car and good battery.  But most people are not aware that this procedure can be very hazardous until a tragic accident occurs while doing it.

Every year, hundred of injuries result from car batteries that explode while they are being jump started.  The reason they explode is that in the cranking procedure of starting the car, the battery generates a lot of hydrogen gas as a by-product of the chemical reaction that produces the electrical energy.  It takes only a small spark to cause it to explode, and sparks are what you get when you improperly attach jump start cables to batteries.  (Remember the Hindenburg?  It was filled with hydrogen.)

In addition to the danger of hydrogen, you should keep in mind that leaking carburetor or fuel lines may drop gasoline in the engine compartment and it also may explode or catch fire when sparks are ignited nearby.

An exploding car battery is like a bomb that sprays chunks of the plastic casing and sulfuric acid into the face or body of anyone nearby.  The most vulnerable part of your body in such an accident is your eyes.  Lacerations of the eyeball and acid burns causing loss of eyesight could be the price you pay for a moment of carelessness.

The proper way to jump start a car does not cause sparks around the dead battery and will minimize the risk of explosion.  Please keep this paper in the glove compartment of your car.  It may come in handy some cold winter day and might save you from dangerous eye injuries.

You probably should see about getting a new battery, if the one that failed is over two or three years old.

How to Jump Start Your Car

 Make sure your jumper cable set is color coded so you can tell the two cables apart and identify both ends of the same cable.  Before you begin

  • Wear eye protection and do not lean over the battery.
  • Do not smoke cigarettes.  If you need light, use a flashlight, not a match.
  • Be sure the vent caps are tight on the battery.
  • Be sure that both batteries are of the same voltage.
  • Be sure that the two cars are not touching each other and the parking brakes of both cars are firmly set.

Then follow this sequence:

  1. Attach the red cable to the positive (+) terminal of the dead battery.  The metal part of the cable must not touch the other cable or anything else that is metal.
  2. Attach the other end of the same (red) cable to the positive (+) terminal of the good battery in the other car.
  3. Attach one end of the black cable to the negative (-) terminal of the good battery.
  4. To make the final connection to the disabled car, attach the other end of the second (black) cable to any metal engine or body part.  Do NOT attach this cable to the negative (-) terminal of the dead battery.  Be careful not to attach to any part near the carburetor line (This is called the “ground” cable.
  5. Start the “good” car, run several minutes, then start the disabled car.  Stay away from the engine compartments as both cars are started.
  6. When removing the jump cables once the disabled care has started, be careful you do not let any clamp touch any other metal while the other end remains attached.  Remove the cables in reverse order:
  • 1)    The “ground” cable.
  • 2)    The cable from the negative (-) terminal of the good battery.
  • 3)    The cable from the positive (+) terminal of the good battery.
  • 4)    The cable from the positive (+) terminal of the dead battery

7.  Run or drive the car with the “dead” battery at least 15 to 30 minutes                     before shutting it off.  This should charge the battery enough so the car will start the next time.

Information excerpted from "Triad Notes" with permission. 

Dr. Jeffrey D. Gold is an award winning surgeon practicing at Liberty Vision in Hamden, CT. Dr. Gold specializes in epi-LASIK Vision Correction.