Which Terminal Do You Connect First When Jump-Starting a Car?
- by Joe Weber - updated on 7/9/2025
If your car battery is dead, a jump-start might be all you need to get back on the road. But before you grab those jumper cables, it's important to know the correct way to connect them. Improperly jump-starting your vehicle can be dangerous for both you and your car's electrical system.
In this guide, we'll break down the safest way to jump-start your car, which battery terminal you should connect first, and why it matters. Additionally, discover how Batteries Plus can assist with expert battery testing, car and truck replacement batteries, and professional installation in as little as 30 minutes at many of our locations.
Key Takeaways:
- Always connect the positive terminal first when jump-starting a car.
- Follow the correct jump-starting sequence to avoid injury or damage.
- Many Batteries Plus stores offer on-site car battery installation in under 30 minutes.
- We provide free battery testing and sell top brands like Duracell Ultra.
What You'll Learn:
- The correct order to connect jumper cables
- Why the connection sequence matters
- Signs your car battery may need replacement
- How Batteries Plus can help with battery issues
Which Battery Terminal Do You Connect First?
Always connect the positive terminal first when jump-starting a car. Here's why:
The positive terminal is part of your car's electrical circuit. Connecting it first reduces the risk of sparks, which can occur if you connect the negative terminal first and accidentally touch metal with the other clamp. These sparks can ignite the hydrogen gas emitted by the battery, posing a risk of fire or explosion.
Step-by-Step Guide: How to Jump-Start a Car Safely
- Park both cars: Make sure the vehicles are in park or neutral with the ignition off. Engage the parking brakes.
- Identify the terminals: Locate the positive (red, marked "+") and negative (black, marked "–") terminals on each battery.
- Connect the jumper cables:
- Red clamp to the dead battery's positive terminal
- Red clamp to the good battery's positive terminal
- Black clamp to the good battery's negative terminal
- Final black clamp to unpainted metal surface on the engine block or car frame of the dead vehicle (not the battery!)
- Start the working vehicle and let it run for a few minutes.
- Try starting the dead car.
Once the car starts, you can carefully remove the jumper cables in reverse order. Don't turn the car off right away; let it run for a few minutes, or better yet, take it for a nice highway drive.
For a more in-depth look at this procedure, please read our helpful guide "5 Easy Steps To Jump Start Your Car".
Why You Should Never Connect A Negative Cable to a Dead Battery
Connecting the negative cable to the dead battery's negative terminal increases the risk of sparks near the battery. Instead, you should always ground the final clamp to an unpainted metal surface on the engine block or car frame of the dead vehicle, not the battery itself. This helps disperse the charge safely and reduces the chance of a spark igniting any hydrogen gas emitted by the battery.
Important note: Some vehicles feature a dedicated "ground" post under the hood, designed specifically for jump-starting. If your vehicle has one, always use this post for the final negative connection. It's typically marked and located away from the battery to provide a safe, spark-free grounding point.
What If Your Car Still Won't Start?
If your car still won't start after attempting a jump, your battery might not be the issue, or it may be beyond saving. Here are a few common reasons your car may not start, even after jump-starting:
Possible Causes:
- Completely dead battery that won't hold a charge
- A faulty alternator that isn't recharging the battery
- Bad starter motor
- Loose or corroded battery terminals
- Blown fuse or electrical issue
- Damaged or frayed battery cables
Even if your vehicle does start after a jump, these warning signs could indicate your battery is nearing the end of its life:
Signs Your Battery May Be Failing:
For a deeper dive into these warning signs, check out our blog on how to tell if your car battery is dying.
- Your engine cranks slowly or clicks when you turn the key
- Dim headlights or flickering interior lights
- Electrical accessories (radio, power windows, etc.) don't work properly
- The dashboard battery warning light stays on
- You've needed multiple jump-starts in a short period
- Your battery is over 3–5 years old
Still not sure what's wrong? Visit your local Batteries Plus for a free battery test. We'll diagnose the issue and help you find the right replacement if needed. All of our locations even offer professional installation on-site in as little as 30 minutes, getting you back on the road faster.
Trust the Battery Experts at Batteries Plus
Whether you drive a compact coupe, a heavy-duty truck, or something in between, we have the right battery for your vehicle. Our top-quality selection includes trusted brands like Duracell Ultra, Optima, and our premium brand X2Power, and our team can help you find the perfect match based on your make and model.
When you shop at Batteries Plus, you're getting more than just a product—you're getting professional support backed by decades of expertise in automotive batteries.
FAQs
Q: Can I jump-start a car with just the positive terminal?
A: No, you cannot successfully jump-start a car using only the positive terminal. A complete circuit is required, which means you need both the positive and negative (ground) connections.
Without grounding the negative side—either to the good battery's negative terminal or a proper ground point on the dead vehicle—the electrical current won't flow, and the jump-start won't work.
Q: Do I connect positive or negative first when jump-starting a car?
A: Always connect the positive terminal first. This reduces the risk of sparks or battery damage.
Q: Can I jump-start a car with a portable jump starter instead of jumper cables?
A: Yes, you can! A portable jump starter (also known as a jump box or battery booster) is a convenient and effective alternative to using another vehicle and jumper cables when there are no other vehicles around to jump from.
Q: Why can't I connect the negative jumper cable to the dead battery?
A: Connecting the negative cable to the dead battery can cause sparks near the battery. Always ground it to an unpainted metal surface instead.
Q: How do I know if my battery needs to be replaced?
A: If your car struggles to start, has dim lights, or you've jump-started it more than once recently, it's likely time for a replacement. Visit Batteries Plus for free battery testing to know for sure.
Q: Can I get my car battery replaced at Batteries Plus?
A: Yes! All of our locations offer professional car battery installation, often in 30 minutes or less, depending on how busy the store is and the difficulty of the install.
Q: What brands of car batteries does Batteries Plus carry?
A: We offer top brands like Duracell Ultra, Optima, and X2Power, built for reliable performance and long-lasting power to keep your car or truck on the road.
Stop by Your Local Batteries Plus Today
Need help with a dead battery? Don't stress—just visit your nearest Batteries Plus. Our team can test your battery, recommend the best replacement, and even install it for you, often in as little as 30 minutes. With trusted brands like Duracell Ultra and knowledgeable service, we make it easy to get back on the road quickly and safely.
When it comes to your vehicle's battery, don't leave it to guesswork—trust the Experts in Charge.