Jump leads are one of the simplest pieces of roadside equipment you can keep in a car. When a battery goes flat, a good set of jump leads can transfer power from another suitable vehicle and help get the engine started.
However, connecting jump leads incorrectly can damage a battery or the vehicle’s electrical system. It is important to follow the correct procedure and check your vehicle’s manual before attempting a jump start.
What Are Jump Leads?
Jump leads, also called jumper cables or booster cables, are a pair of heavy-duty electrical cables with clamps at both ends.
They are normally colour-coded:
- Red: Positive (+)
- Black: Negative (-)
The leads connect a vehicle with a flat battery to a suitable power source, normally another vehicle with a charged battery.
When Do You Need Jump Leads?
The most common situation is a flat car battery.
You may notice signs such as:
- The engine does not crank
- You hear clicking when trying to start
- Interior lights are weak
- Headlights are unusually dim
- The central locking may not work
- The dashboard may fail to illuminate properly
A flat battery can happen because lights were left on, the car was unused for a long time, an electrical system drained the battery or the battery is reaching the end of its useful life.
What You Need Before Using Jump Leads
Before attempting a jump start, you normally need:
- A suitable set of jump leads
- Another vehicle with a suitable charged battery
- A safe place to park
- Both vehicles’ owner manuals where available
Do not attempt to jump-start a battery that is visibly cracked, leaking or severely damaged.
You should also make sure the vehicles use compatible electrical systems. Check the manufacturer’s instructions, especially with newer vehicles, hybrids and vehicles with unusual battery arrangements.
How to Connect Jump Leads
The connection order matters.
First, switch off both vehicles and all unnecessary electrical equipment. Put the vehicles in park or neutral with the parking brakes applied.
Then:
- Connect the red clamp to the positive (+) terminal of the flat battery.
- Connect the other red clamp to the positive (+) terminal of the charged battery.
- Connect the black clamp to the negative (-) terminal of the charged battery.
- Connect the remaining black clamp to a suitable unpainted metal earth point on the vehicle with the flat battery, if the manufacturer’s instructions specify this method.
Keep the clamps away from moving engine components such as belts and fans.
Starting the Vehicles
Once the leads are connected correctly, start the vehicle providing the power and allow it to run for a short period according to the vehicle manufacturer’s guidance.
Then attempt to start the vehicle with the flat battery.
Avoid repeatedly cranking the starter for long periods. If the vehicle does not start after several attempts, there may be a problem beyond the battery.
The issue could involve the starter motor, alternator, battery itself, fuel system or another electrical component.
How to Remove Jump Leads
Once the vehicle has started, remove the leads in the reverse order.
A common sequence is:
- Remove the black clamp from the previously flat vehicle’s earth point.
- Remove the black clamp from the charged battery.
- Remove the red clamp from the charged battery.
- Remove the red clamp from the previously flat battery.
Keep the clamps separated and away from metal parts while disconnecting them.
Always follow the specific instructions in your vehicle’s manual if they differ.
Can Jump Leads Damage a Car?
Yes, incorrect use can cause problems.
Connecting the positive and negative terminals incorrectly can create sparks and potentially damage batteries or electrical components. Modern vehicles can have sensitive electronic systems, so a jump start should not be treated as something to do carelessly.
If you are unsure about the connection points or your vehicle has special jump-start terminals, check the owner’s manual or get professional assistance.
Choosing Good Jump Leads
Not every pair of jump leads is equally useful.
When buying a set, consider:
Cable Thickness
Thicker cables are generally better suited to carrying the high current required during engine starting.
Cable Length
Longer leads give you more flexibility when the two vehicles cannot be positioned very close together.
Clamp Quality
Look for strong clamps that grip the battery terminals securely and have good insulation around areas that could accidentally make contact with metal.
Storage
A set that comes with a storage bag or case is easier to keep organised in the boot.
Jump Leads vs Portable Jump Starter
Jump leads require another suitable vehicle to provide the power.
A portable jump starter, on the other hand, contains its own battery and can be used without another vehicle.
For drivers who frequently travel long distances, a portable jump starter can be useful because you may not always find another vehicle nearby.
Whichever option you choose, learn how it works before an emergency occurs.
Can You Keep Jump Leads in Your Car?
Yes. Jump leads are relatively easy to store in the boot and can be useful during unexpected battery problems.
They are particularly practical for drivers who regularly travel between cities or spend long periods away from home.
Keep them somewhere accessible rather than underneath heavy luggage where you cannot reach them easily.
What If the Car Needs Jump Starting Repeatedly?
If your vehicle needs jump starting regularly, do not treat the jump leads as a permanent solution.
A healthy battery should not normally require repeated jump starts simply to get the car running.
The battery may be weak, the alternator may not be charging properly or another electrical system may be draining the battery when the vehicle is parked.
A battery and charging-system test can help identify the actual problem.
Jump Leads for Long-Distance Travel
Before an interstate journey, check the condition of your battery and make sure your roadside equipment is available.
Alongside jump leads, useful items can include:
- Spare tyre or approved puncture equipment
- Wheel spanner
- Jack
- Tyre pressure gauge
- Portable tyre inflator
- Torch
- Warning equipment
- Basic toolbox
A few minutes of preparation before leaving can save a lot of stress if something goes wrong during a journey.
Important Safety Precautions
Never smoke or create an open flame around a vehicle battery.
Do not allow the positive and negative clamps to touch each other while they are connected to a power source.
Do not attempt a jump start if the battery is visibly damaged, leaking or otherwise unsafe.
Also check the vehicle manufacturer’s instructions before connecting anything, particularly with modern cars, hybrids or vehicles with dedicated jump-start points.
If you are not confident about the process, calling a qualified mechanic or roadside assistance provider is safer than guessing.
For Nigerian drivers travelling for work, family visits or interstate trips, Travo.ng can also assist with relevant travel and mobility arrangements when a vehicle problem affects your plans.
Jump leads are a small addition to a car’s emergency kit, but they can be extremely useful when a battery unexpectedly goes flat. Keep a quality set in the vehicle, understand the correct connection order and check your car’s manual before using them.
