## Do You Rev the Engine When Jumping a Car?
Introduction
Jumping a car, also known as boost starting, is a common roadside procedure used to start a vehicle with a dead battery. The process involves using another vehicle with a functional battery to provide power to the disabled vehicle, allowing it to start its engine. However, there is some debate on whether it is necessary or beneficial to rev the engine of the donor vehicle while jump-starting the disabled car.
Understanding the Jump-Starting Process
To jump-start a car, you will need:
* A donor vehicle with a working battery
* A pair of jumper cables
* Safety glasses
**Step 1: Safety First**
Before connecting the jumper cables, put on safety glasses to protect your eyes from potential sparks. Park both vehicles close together, ensuring that they are not touching.
**Step 2: Connect the Cables**
Connect one end of the positive (red) cable to the positive terminal of the donor battery. Connect the other end of the positive cable to the positive terminal of the disabled battery. Connect one end of the negative (black) cable to the negative terminal of the donor battery. The other end of the negative cable should be connected to an unpainted metal surface on the disabled car, such as the engine block or a bolt.
To Rev or Not to Rev?
The question of whether or not to rev the engine of the donor vehicle while jump-starting a car has divided mechanics and enthusiasts alike.
**Arguments for Revving**
Proponents of revving the engine argue that it can help in the following ways:
* **Increases alternator output:** Revving the engine increases the speed of the donor vehicle’s alternator, which in turn generates more power to flow through the jumper cables.
* **Overcomes internal resistance:** The disabled battery may have internal resistance that hinders the flow of current. Revving the donor vehicle’s engine can help overcome this resistance and deliver more power to the disabled battery.
* **Shortens the jump-start time:** By providing more power, revving the engine can reduce the time required to jump-start the disabled car.
**Arguments Against Revving**
Opponents of revving the engine claim that it:
* **Can damage the donor vehicle:** High engine speeds can strain the donor vehicle’s alternator and other electrical components, potentially leading to damage.
* **Unnecessary force on the jumper cables:** The high voltage generated by revving the engine can put undue stress on the jumper cables, increasing the risk of cable damage or sparking.
* **Increases the risk of electrical damage:** Revving the engine can produce voltage spikes that could damage sensitive electronic components in the disabled car.
* **Can hinder the flow of current:** In some cases, revving the donor vehicle’s engine can create an imbalance in the electrical systems of both vehicles, hindering the flow of current to the disabled battery.
Best Practices
Given the conflicting arguments, it is important to follow established best practices when jump-starting a car:
* **Ensure a stable connection:** Make sure the jumper cables are securely connected to the battery terminals and the engine block.
* **Avoid high engine speeds:** If possible, refrain from revving the donor vehicle’s engine excessively. Keep the RPMs at a moderate level.
* **Monitor the battery voltage:** Use a voltmeter to monitor the voltage of the disabled battery. Once the voltage reaches around 12.5 volts, you can attempt to start the disabled car.
* **Disconnect the cables in reverse order:** Once the disabled car has started, disconnect the jumper cables in reverse order: negative cable first, then positive cable.
Conclusion
Whether or not to rev the engine when jumping a car is a matter of debate. While some proponents argue that it can help increase power flow and shorten the jump-start time, others caution against it due to potential risks of electrical damage and strain on the donor vehicle. To ensure a safe and successful jump-start, it is always advisable to follow established best practices and avoid excessive engine revving.
