How to Use Jump Leads to Start a Car: A Step-by-Step Guide

There’s nothing more frustrating than getting into your car, turning the key, and hearing... nothing. A flat battery can happen to anyone, especially during cold Irish winters or if you’ve accidentally left your lights on. But the good news is, with a set of jump leads and a helping hand, you can get back on the road quickly and safely.

In this comprehensive guide, we’ll walk you through how to use jump leads to jump-start your car in Ireland. Whether you're a seasoned driver or a young driver, this easy-to-follow guide will help you stay calm and confident in a battery emergency.

What Are Jump Leads?

Jump leads (also known as jumper cables) are insulated wires with clips at both ends, used to transfer power from a working car battery to a dead one. They are a must-have in your car emergency kit and can be a real lifesaver in unexpected breakdowns.

Jump starting a car with leads is a simple task, but it must be done correctly to avoid damaging your car—or yourself. Let’s get started.

Before You Start: Safety First!

Jump-starting a car is generally safe when done properly, but it does involve electricity and cars with potentially faulty batteries. Here are some safety checks to make before connecting jump leads.

Gather Your Supplies. You'll need:

- A set of quality jump leads (preferably with surge protection)

- A second car with a fully charged, same-voltage battery (usually 12 volts)

- Gloves (optional but recommended)

- Safety glasses (optional)

Inspect Both Car Batteries

Check both batteries for visible damage, leaks, or corrosion. If the battery is cracked or leaking, do not attempt to jump-start it—call for professional help. Make sure the batteries are not frozen. Jumping a frozen battery can cause the battery to explode.

Park Both Cars Safely

• Park the working car nose-to-nose or side-by-side with the dead car so the leads can reach.
• Turn off both vehicles and remove the keys from the ignition.
• Engage the handbrakes and put the vehicles in neutral (manual) or park (automatic).
• Now you’re ready to start connecting the jump leads.

Step-by-Step Guide: Connecting the Jump Leads

Follow these steps carefully to avoid damaging either vehicle.

• Step 1: Connect the Red Clamp to the Positive (+) Terminal of the Dead Battery

Find the positive terminal, usually marked with a plus sign (+) or red cover. Attach one end of the red (positive) lead to this terminal.
 

• Step 2: Connect the Other Red Clamp to the Positive (+) Terminal of the Working Battery

Attach the other end of the red lead to the positive terminal of the fully charged battery.
 

• Step 3: Connect the Black Clamp to the Negative (-) Terminal of the Working Battery

Attach the black (negative) clamp to the negative terminal (marked with a minus sign [-]) of the working battery.
 

• Step 4: Connect the Other Black Clamp to an Unpainted Metal Surface on the Car with the Dead Battery

Do not connect this clamp directly to the dead battery. Instead, attach it to a clean, unpainted metal surface on the engine block or chassis. This minimises the risk of sparks near the battery.

Now that the leads are connected, it’s time to bring the dead battery back to life.

Start the Working Car: Let it run for a few minutes

Start the engine of the car with the charged battery and let it idle for about 3–5 minutes. This gives the dead battery time to gain some charge.

Try to Start the Car with the Dead Battery

After a few minutes, try starting the car with the flat battery. If it turns on—great! Let it run while still connected for a few more minutes.

If It Doesn’t Start: Wait and Try Again

If the dead car doesn’t start, wait another 3–5 minutes and try again. Still nothing? The battery may be beyond repair, or there could be another issue.

Disconnecting the Jump Leads

It’s just as important to remove the jump leads in the correct order to avoid sparks or damage.

1. Disconnect the Black Clamp from the Metal Surface

2. Remove the black clamp from the metal grounding point on the car that was jump-started.

3. Disconnect the Black Clamp from the Negative (-) Terminal of the Working Battery

4. Now, disconnect the black clamp from the working battery.

5. Disconnect the Red Clamp from the Positive (+) Terminal of the Working Battery

6. Carefully remove the red clamp from the working battery.

7. Disconnect the Red Clamp from the Positive (+) Terminal of the Jump-Started Battery

Finally, disconnect the red clamp from the battery that was dead. Make sure none of the clamps touch each other or any metal surfaces while you store them.

What to Do After Jump-Starting Your Car

Drive Your Car for at Least 30 Minutes

Take your car for a 30-minute drive or let it idle with all accessories off. This allows the alternator to recharge the battery. Avoid turning off the engine during this time, especially if your destination is close by.

Get Your Battery Tested

Even if your car is running, it’s a good idea to have the battery tested by a mechanic or garage. It may need replacing, especially if this isn’t the first time it’s gone flat.

Routine maintenance like this contributes to long-term safety and peace of mind. For more advice, check out our driving safety tips.

When to Call for Professional Help

Jump starting isn’t always the best option. Sometimes, it's better to let the experts handle it.

If the Battery is Damaged

If the battery looks swollen, corroded, leaking acid, or has a foul smell, do not attempt to jump-start it. Call roadside assistance or a mechanic.

If the Car Won’t Start After Multiple Attempts

If the car doesn’t respond after a few jump-start attempts, there could be a deeper electrical or mechanical problem. In this case, professional help is required. AIG customers benefit from breakdown assistance and other useful extras, giving you peace of mind whenever you hit the road.

AIG Car Insurance: Peace of Mind on the Road

A dead battery is just one of many things that can go wrong when driving. That’s why it’s important to have reliable car insurance with helpful features that support you when you need it most.

Benefits of AIG Car Insurance

With an AIG policy, you get more than just cover. Enjoy benefits like:

- 24/7 roadside assistance

- Breakdown cover

- Claims support from a trusted Irish brand

- Flexible policies for new and experienced drivers

Looking for better car insurance? Visit AIG Ireland to explore your options and get a personalised quote in minutes.

Knowing how to use jump leads is an essential life skill for every Irish driver. Whether you’re commuting in Dublin, exploring the Wild Atlantic Way, or just heading to the shops, being prepared for a flat battery can save you time, stress, and money. It’s just another one of the skills you should know when owning a car.

By following this guide and staying safe, you’ll be able to jump start a car with leads confidently and safely. And if you ever feel unsure, remember that AIG is here to help with support, guidance, and car insurance that keeps you covered. For more helpful driving tips and breakdown advice, explore our full range of driving safety tips today.

Stay safe—and don’t forget to keep those jump leads in your boot!