Jump-starting a vehicle with certain battery faults can cause extensive electrical system damage.
RACQ Road Service staff are trained to identify these faults as well as in safe jump starting procedures and we would always recommend calling for their assistance. However, if this is inconvenient or not possible, the following procedure is provided.
It is the safest possible without the use of specialised equipment and training and is suitable for boost starting all vehicles, provided they are both negative ground and the system voltages are the same.
The procedure given here is not jump starting per se. It is actually a method of getting enough charge into the discharged battery to allow the engine to be started without assistance.
If after following this procedure the engine still cannot be started, or cannot be started without further assistance, it is likely that the vehicle has other problems. The starting attempt should be abandoned and assistance sought to identify and correct the problem.
Before proceeding, ensure that the ignition of both vehicles and anything that could cause an electrical load i.e. headlights, interior light etc., are turned off, and keys are removed from the ignition of both vehicles. Refer to "Important Safety Information" below before commencing the procedure.
- Make sure that the vehicles are not touching each other and that the jumper lead clamps do not touch each other or any part of either vehicle except as outlined in the following procedure.
- Connect the red lead to the positive (+) terminal of the discharged battery.
- Connect the other end of the same red lead to the positive (+) terminal of the booster battery.
- Connect the black lead to the negative (-) terminal of the booster battery.
- Connect the other end of the same black lead to a solid stationary metal component on the engine of the vehicle with the discharged battery.
Note: Vehicle batteries are increasingly being located in areas other than the engine compartment.
In such cases it may not be practical to attempt to connect jumper leads directly to the battery. Many vehicles of this type have dedicated jump starting connections in the engine compartment. These will be shown in the vehicle's handbook.
6. Start the engine in the vehicle with the discharged battery (do not start the engine of the vehicle with the good battery) and let it run at idle for at least ten minutes with all accessories off, to charge the battery. If the engine cannot be started at this point refer to the note below *.
7. After ten minutes turn off the engine, remove ignition keys and disconnect the leads in the reverse order. Do not disconnect any leads while the engine is running.
8. Attempt to re-start the engine of the vehicle with the discharged battery. If the engine will not start there is a reasonable chance that the battery or the alternator is faulty, or, the battery is still insufficiently charged.
Repeat steps 1 to 7. If after repeating these steps the vehicle will still not start, the boost start attempt should be aborted. The charge system should be checked and the battery charged, tested and if necessary replaced.
* Note: If the engine in the vehicle with the discharged battery cannot be started it could mean that:
- It has other problems not necessarily related to the battery.
- The battery is so discharged that the jumper leads are incapable of passing enough current to start it.
- The jumper leads are inadequate for the task.
Important Safety Information
- Do not connect the lead directly to the negative (-) terminal of the discharged battery or to fuel lines or air conditioner pipes.
- Take care that the jumper lead clamps do not touch each other and are clear of cooling fans, drive belts and other moving parts.
- Do not lean over the battery when making connections.
- Keep sparks and flames away from batteries as they may explode.
- Do not disconnect or change over the discharged battery while the engine is running as damage to the electrical system can occur.
- Check oil and coolant levels, and top up if necessary, before starting the engine.
- If the charge indicator shows a fault, (the alternator light does not operate or is on) the procedure should be abandoned and any necessary repairs attended to.
- The engine must only be run in a well-ventilated area due to the dangers of exhaust gas build up.
- Never leave an engine running unattended. You must be present to ensure that it does not overheat.
Operating a vehicle with certain battery faults or disconnecting jumper leads while either engine is running can cause voltage spikes that can damage sensitive electronic components and the vehicle’s electrical system.
Unless the cause of the battery discharge is known, for instance lights left on, the battery condition and electrical system should be checked to locate the source of the problem.
Simply driving a vehicle with a discharged battery will not restore full charge. In every case the battery must be recharged with a battery charger.