Search Cars for Sale

How to Jump-Start a Car Battery

Knowing how to jump a car battery is a basic skill that every driver needs.

Like fixing a flat, jumping your car isn’t something that’s done regularly and never at a convenient time. With some knowledge and by following a few simple steps, it doesn’t take long to jump-start a car. You can be back on the road in a matter of minutes.

Jump-starting a car requires jumper cables, also known as booster cables, to connect the dead battery in your car to a fully charged battery in another vehicle. It’s a great idea to keep a good set of cables along with other roadside emergency equipment in the trunk of your car.

Read on to learn how to jump-start a car using these instructions.

Steps to Jumping a Car with a Dead Battery

1. Position the Booster Vehicle

First, park a vehicle with a full battery close to the car with the discharged battery. The vehicles can be beside each other or facing bumper-to-bumper. They must be close enough to allow the jumper cables to reach the batteries.

Shut off the ignition on both cars and remove the keys. Set the emergency brake in both vehicles. Turn off all accessories, including climate control, lights, and radio.

Note: Most gasoline-powered vehicles have batteries under the hood. However, the battery is found in the trunk or under the back seat in some models. Arrange the car with its good battery accordingly. Check the vehicle’s manual if its battery location isn’t known.

2. Locate Battery Terminals

Raise the hood of the cars to access the batteries. A car battery has two terminals – positive (+) and negative (-). Sometimes the battery terminals are hidden, and remote metal posts are placed for convenient access to jump the battery or provide a boost. The positive terminal often is identified with a red cap. Refer to the vehicle manual for terminal locations if necessary.

The terminals should be free from corrosion. If the posts seem coated with a white or greenish substance, remove it using a wire brush, aluminum foil, or anything except your bare hand. The corrosion can irritate your skin.

Do not attempt to jump the battery if it is cracked or leaking.

3. Connect Jumper Cables

Jumper cables have a pair of spring-loaded clamps at each end — one red and one black. Red clamps attach to positive battery terminals; black clamps are for negative posts or grounding. It’s essential to connect the four clamps securely and in the correct sequence. Improper connection can result in personal injury or damage to the cars’ electrical system.

Keep the metal clamps from touching each other while clipping onto the batteries.

  • First, attach a RED clamp to the positive terminal of the DEAD battery.
  • Next, attach the RED clamp from the other end of the cables to the BOOSTER battery’s positive terminal.
  • Then, attach the BLACK clamp to the negative terminal of the BOOSTER battery.
  • Last, attach the BLACK clamp to the negative terminal of the DEAD battery or an unpainted metal part on the car engine, such as a bolt or bracket. Some models have a grounding bolt placed solely for this purpose.

4. Jump-Start the Car

Double-check that the connected booster cables aren’t near moving engine parts. Start the engine of the vehicle that’s donating the electricity.

Then start the car with the weak battery. If the engine doesn’t turn over right away, you might need to wait a few minutes to allow the battery to build a sufficient charge. Increasing the idle speed of the booster vehicle may help make this happen more quickly.

Note: A dead car battery never gets discovered at a convenient time, and foul weather can add to the inconvenience. If you’re wondering if you can jump a car in the rain, don’t worry — it’s safe. Even with the additional moisture, the vehicle battery’s voltage isn’t high enough to make the task more dangerous than jump-starting on a dry day.

5. Disconnect Jumper Cables

With the jump-started car’s engine running at a smooth idle, disconnect the jumper cables in the reverse order they were attached. Always keep the metal clamps from touching each other when connecting and disconnecting them from battery terminals.

  • Disconnect the negative clamp from the jumped car.
  • Next, disconnect the negative clamp from the booster car.
  • Then, disconnect the positive clamp from the booster car.
  • Last, disconnect and remove the positive clamp from the jumped car.

6. Drive the Jumped Car

Return the emergency cables to your emergency kit and close the car’s hood. Then drive the jump-started car for at least 20 minutes to allow the alternator to charge the jumped battery.

Be sure to park the vehicle in an open area of a safe location when you turn the engine off, in case the car needs jump-starting again. If it does need another jump, the battery’s condition could be deteriorating, especially if it’s more than a few years old.

Many auto parts stores that sell batteries can run a diagnostic check on the car battery to identify whether a replacement is needed.

Jumping a Hybrid Car or Electric Vehicle

With the number of electric cars on the road increasing, more people ask if or how you jump a car if it’s a hybrid. The simple answer is that an electric car or hybrid vehicle gets jump-started using a process similar to a traditional gas-powered car.

It’s important to note that hybrids have two batteries: A 12-volt battery – like a traditional car battery – and the more robust setup that powers the electric motor.

Many manufacturers have located hybrids’ auxiliary 12-volt battery in unusual places. Some have placed jump-start tabs under the hood in the fuse box for convenience. Because this varies by make and model, it’s best to refer to the vehicle’s manual for guidance on jump-starting a hybrid.

EVs have a similar situation. A 12-volt battery keeps electronics working while the EV is powered down. If this gets discharged, it could use a jump to get the motor working. You won’t be able to jump-start an EV using a second EV, even if they are the same brand.

The 12-volt system on electric vehicles isn’t designed to provide this kind of service to a second EV.

TIP: Use a gas-powered car or a portable jump-start device when faced with a dead electric car battery.

FAQs for Jump-Starting a Car

Can You Jump-Start a Car with a Bad Starter?

When your car’s starter will not engage, the easiest thing to do is try to jump-start the vehicle and get it to a qualified mechanic at an auto repair shop or dealership. If a jump-start doesn’t help the bad starter, then the next step is getting towed and get it repaired.

Could a Car Battery be Too Dead to Jump-Start?

A car battery can be too dead to start. You see, car batteries do wear out and can get terminally damaged over time. Battery life usually lasts from three to five years and eventually needs replacing. So, it’s possible that a car battery can be too dead to jump.

Factors that shorten the life of your battery include defective cells, weather, and where you live. You see, excessive heat can wear out your car battery quicker. Batteries can also short circuit, terminals can get corroded or loose, and other things can happen to shorten the life of your battery.

Can You Jump-Start a Motorcycle with a Car?

Yes, you can, with an asterisk. If you get caught unprepared without a battery charger for your motorcycle, you can safely jump-start a motorcycle battery with a car. The different size batteries do not matter. As long as the motorcycle and car batteries use 12 volts and have negative grounding, they will work safely. However, it’s best to use motorcycle jumper cables. With car jumper cables, the larger clamps make it more tricky and difficult to attach safely on a motorcycle. For safety reasons, it’s not wise.

When you’re ready to jump-start a motorcycle with a car, the process works the same way. Follow the directions in your motorcycle manual for hooking up the jumper cables so you don’t create a spark. When your motorcycle battery starts up, go get it checked.

Is it Possible to Jump-Start a Car in the Rain?

It’s safe to jump-start a car when it’s raining as long as there’s no water dripping down the cables. Just make sure you use jumper cables in good working condition, and use an umbrella to keep the battery protected. Then, follow the directions for attaching the jumper cables clamps and you can jump-start a car in the rain safely.

Read Related Stories:

Sign up for Autotrader newsletters

The best cars and best deals delivered to your inbox

Email Address 

By subscribing, you agree to our privacy policy

Where You Can Buy

Loading dealers...

Leave a Comment

Most Popular Articles

2020 Hyundai Sonata Hybrid: First Look

The 2020 Hyundai Sonata Hybrid jumps to the head of the hybrid class.

Best Truck Deals: April 2021

These are the best deals on trucks for the month of April.

Search By Style

More Articles Like This