How to Jump-Start a Car

December 05, 2023

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A dead car battery can make even the best of days take a turn for the worse, but equipping yourself with the knowledge of how to jump-start a car can safely get you back on the road in no time.

While you can experience a dead battery any time of the year, car batteries are especially prone to losing power when the weather outside turns cold.

Luckily, jump-starting a car is easier than it may seem. You just need some jumper cables and a family member, neighbor or friendly stranger with a car to get started.

Learning Positive vs. Negative Terminals and Cables

Before you connect jumper cables to battery terminals, you may be wondering, “Is red or black positive?” when it comes to the cable colors. 

It’s extremely important to learn the difference because connecting the wrong cable and terminal, or even connecting the correct cable and terminal but in the wrong order, can be dangerous. Connecting cables and terminals improperly may damage or ruin the battery, destroy the entire electrical system of the car, or shock and injure you.

Red is positive. The red cable is the positive cable. However, if your jumper cables aren’t color-coded, look for a plus sign (+) to identify the positive cable. This will connect to the positive battery terminal, also marked with a “+.”

Black is negative. The black jumper cable is typically negative. Of course, if your jumper cables are both black, look for the negative symbol, a minus sign (-), to find the negative cable and battery terminal.

How to jump start a car

How to Connect Jumper Cables

When jumping a car, which cable goes on first? It’s important to know the exact order to connect your jumper cables; otherwise, you could damage your car's electrical system. Attaching the cables appropriately is also important for preventing sparks, which could ignite and cause a fire.

Take the keys out of the ignition before starting. Think back to science class. Metal is a good conductor of electricity, and while you do need electricity to flow easily when jumping your battery, you don’t want that happening when your cables aren’t attached yet. Before you start, take the keys out of your vehicle ignition and out of the jumper or booster car’s ignition.

Cables should never touch one another. To further minimize the risk of shocks or electrical damage to your vehicle, ensure the cable clamps (the metal parts of the vehicle cables) never touch each other.

Make sure vehicles don’t touch. Finally, before you start connecting jumper cables, make sure the car with the dead battery and the car you are using to help jump the battery aren’t touching as an extra safety precaution.

Attach the red cable to the positive terminal on the dead battery first. Start with the positive cable and attach one of the end clamps to the positive terminal on the dead battery.

Attach the red cable to the positive terminal on the jumping battery. Next, attach the clamp to the other end of the red cable to the booster battery’s positive terminal.

Attach the black cable to the negative terminal on the jumping battery. Now, attach one clamp from the black or negative cable to the jumper or booster car’s battery.

Attach the black cable to a grounding element on the dead battery. Do NOT attach the black cable to the negative terminal on the dead battery. Instead, the clamp will go on a grounding element, an unpainted piece of metal, such as a bolt, of the car that has the dead battery.

Now that you know the appropriate and, most importantly, safe order to connect jumper cables, you’re ready to learn how to jump-start a car.

Jumping a Car in 9 Steps

Jump-starting a car is a straightforward process than any DIYer can handle. All you need is some jumper cables and a power source — like another car or a jump starter.

Yes, you can jump a car in the rain! Rainy conditions may be uncomfortable, but you can still safely jump the car battery. If the temperatures outside are cold, though, it may take five or more minutes for the battery to recharge enough to drive again.

No matter the weather, here’s how to jump-start a car battery:

Safety first! Remember to protect yourself with gloves and protective eyewear whenever you're working inside your vehicle.

Recruit someone to help. Unless you have a jump box (more on that later) you’ll need to find someone with a car that can help you jump-start your dead battery. Ask a family member or neighbor if you notice a dead battery at home. If you’re out and about, ask someone in the parking lot for quick assistance. 

Position another vehicle near yours. The easiest way to jump-start a dead battery is to have the two vehicles facing each other without touching, but vehicles can also be side by side.

Open the hood of both cars. With the vehicles in position and turned off, open each car's hood. Depending on your vehicle, you can open the hood from a button inside the car, or there will be a lever or latch under the front of the hood that you can hook and press with your finger to unlatch the hood. Use the hood prop rod, nestled along the front of the hood, to hold the hood open.

Inspect for damage. If your vehicle’s battery is cracked, bulging, leaking or shows other signs of damage, do not continue the process of jump-starting. Have your vehicle towed to an auto shop, or have a professional come out to inspect the damage and recommend next steps.

Connect the jumper cables. Connect the jumper cables using the information in the section above. As a reminder, start by connecting the red cable to the positive terminal of the dead battery, then connect the red cable to the positive terminal of the jumper car’s battery. Next, connect the black cable to the negative terminal on the jumper car’s battery. Finally, connect the black cable to an unpainted piece of metal somewhere on the car that has the dead battery but NOT the negative terminal of the dead battery.

Start the jumper car. After safely connecting the jumper cables, ask the other person to start their car.

Wait a few minutes, then start the car with the dead battery. Give the dead battery a minute or two to recharge before starting the car. Then, start the vehicle.

Disconnect the jumper cables in the correct order. With the vehicles running, you can carefully disconnect the jumper cables. However, be sure to never touch the metal parts of the cables to each other or any other metal parts, and remove the cables in the following order:

  • Remove the negative, black cable from the car with the dead battery.
  • Disconnect the negative cable from the negative terminal on the jumper car.
  • Place the fully disconnected negative cable on the ground, away from the vehicles.
  • Remove the red or positive cable from the jumper car.
  • Remove the red cable from the positive terminal of the car that had the dead battery.

Drive the vehicle. Put the jumper cables back in their place, and thank the helpful person who lent their own car for a jump-start. Now, the jumped battery needs more time to recharge fully. Your vehicle’s alternator will help recharge the battery while the car is in motion, so drive the car around for at least 20 to 30 minutes.

Jumping a Car Without Another Vehicle

A jump box or battery booster is a device with a powerful and rechargeable lithium-ion battery that you can use to jump-start your car’s battery without needing help from another vehicle. 

Battery boosters are convenient, especially if your vehicle battery dies in a more rural or isolated location. They cost more upfront than jumper cables, with boosters costing about $65 to $200 and jumper cables costing about $10 to $50, but they can come in handy when you’re stuck with a dead battery.

Jump-starting a car with a jump box is similar to jumping a car with cables.

Charge the battery booster. Follow the product’s user manual to properly charge up the battery booster. Then, you can store it safely in its case in your vehicle.

Attach the positive cable. Connect the positive cable to the positive terminal on the car battery.

Attach the negative cable. Connect the clamp on the negative cable to an unpainted metal part of the car for grounding.

Turn on the battery booster. With the cables attached and positioned away from any moving parts in the car’s hood, you can turn on the battery booster to start supplying power to the battery.

Turn on the vehicle. Now, turn on the vehicle. If it doesn’t start right away, give it a few minutes to charge up enough to start.

Disconnect the battery booster. At this point, you can disconnect the battery booster by removing the negative and positive cables. Place the battery booster back in its case and store it away.

Drive the car. Don’t forget to drive your car for at least 20 to 30 minutes to give it more time to recharge. The battery booster will give it enough charge to start, but it won’t provide enough power to recharge the battery fully. You may also want to consider connecting the battery to a charger.

Signs Your Dead Battery Needs to Be Replaced

Sometimes, cold weather or parasitic draw, such as from leaving a dome light on overnight, will leave you with a dead battery. Jump-starting the battery can give it a boost, but how do you know when it’s time for a battery replacement? Look for these signs:

Frequent jumps. One major way to tell you need a new battery is if you’re frequently jumping your existing battery. If the battery keeps dying, it has probably reached the end of its lifespan. 

Old battery. Most vehicle batteries today will last about three to five years. If you’re jumping a battery over five years old, it may not just be a one-off instance of a dead battery. The battery is likely too old and needs a replacement.

Sputtering engine. Click, click, click. You turn the key in the ignition, but the engine takes a few tries before it sputters to life. This is a sign of a weak battery in need of replacement.

Jump Start a Car Battery and Be on Your Way

Whether you get help from a friend or stranger with jumper cables or you attempt to jump a car yourself with a battery booster, your recharged battery shouldn’t give you much trouble. Of course, if you need to jump your battery repeatedly, it may be time to consider a new one. Find the right battery for your car with Continental Battery Systems, and you’ll be back on the road with peace of mind.

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