Jump Starting An Engine

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Extreme care must be taken when jump starting an engine or serious bodily injury or damage to the vehicles may result.

If jump starting is not done correctly, expensive damage can be done to a vehicle’s electrical system, particularly to those fitted with electronic ignitions.  Check the vehicle operating manual, if there are no specific instructions, then follow these steps.
When jump started, flat batteries generate high volumes of hydrogen gas which is extremely explosive, so sparks and naked flames must be avoided at all times.  Do not lean over batteries during the operation.  As a precaution, wear safety goggles and a face shield to protect eyes.
First, check to ensure both batteries are the same voltage (6 or 12 volt) and that the two vehicles are not touching each other.  If the failed battery is open circuit do not attempt to jump start.

* Open circuit batteries can be detected by:
· battery volts reading zero immediately after a high rate discharge test is applied.
· when the battery will not accept charge current.

Carefully follow these steps in order:
Step 1
Warning: Jump starting can damage vehicle electronics.  Check the vehicle operating manual.  If there is no specific instructions then follow these steps.  If the failed battery is open circuit* do not attempt to jump start.

Step 2
· Be sure the batteries of both cars are the same voltage (6 volt or 12 volt).
· Drive the donor car close to the disabled car but ensure that the vehicles are not touching.
· Place both cars in neutral or park and apply hand brake.
Make sure both vehicle ignitions are switched to OFF and all electrical equipment is OFF.

Step 3
Connect the vehicles in the following EXACT sequence and make sure the jumper leads are clear of any moving parts.
· Take the RED jumper lead and connect to POSITIVE terminal (marked + or POS) of the discharged battery.
· Connect the other end of the RED jumper lead to the positive terminal of the charged battery.
· Take the BLACK jumper lead and connect one end to the NEGATIVE terminal (marked – or NEG) of the charged battery.
· Make the final connection to the engine block or chassis of the stalled vehicle (negative earth vehicles only).  Never use Air Conditioner, Brakes or Fuel Lines for engine earth.

Step 4
Start the engine of the stalled vehicle.

Step 5
After starting, allow engine of the stalled vehicle to fast idle for a minimum of 10 minutes before disconnecting the jumper leads (see step 6) to allow the cars electrical systems to balance.  This reduces the possibility of damage to vehicle electronics.

Step 6
Remove the BLACK cable first from the vehicle with the discharged battery then the opposite end from the charged battery.  Repeat for the RED cable.

Step 7
After your car has been jump started, the battery should be recharged with a battery charger.

This article is found in the Virtual mechanic CD Rom
You can download it for the price of a latte, but you will learn not to buy a lemon
By Darren Gow-Brown, Melbourne Australia ©2009


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