Last updated: October 29, 2026
Here is how to jump start a car: park a working car close by and turn off both engines. Connect red clamps to both positive terminals, then black to the good battery’s negative terminal and to bare metal on the dead car. Start the working car, wait a few minutes, then start the dead car.
Consumer Reports notes that AAA battery-related roadside service calls exceeded 5.7 million in 2024. Always check your owner’s manual first, because some vehicles have their own procedure.
Contents
- How to jump start a car with jumper cables
- What order do you connect jumper cables?
- Safety checks before you start
- How long to let the car run after a jump start
- How to jump start a car with a battery pack
- Can you jump start a hybrid or electric car?
- Why won’t my car jump start?
- Why batteries die in cold weather
- Frequently asked questions
How to jump start a car with jumper cables
These steps follow the procedure from AAA:
- Position the cars. Park the working car close enough for the cables to reach, leaving a few inches between the vehicles so they do not touch.
- Turn everything off. Shift both cars into park (or neutral for a manual), set the parking brakes, and switch off both ignitions and all accessories.
- Connect the red clamp to the positive (+) terminal of the dead battery.
- Connect the other red clamp to the positive (+) terminal of the good battery.
- Connect a black clamp to the negative (−) terminal of the good battery.
- Connect the last black clamp to clean, unpainted metal on the dead car, such as a thick bolt on the engine block.
- Start the working car and let it run for three to five minutes.
- Start the dead car. Once it runs, leave both cars connected for another three to five minutes.
- Disconnect in reverse order and keep the dead car running.
What order do you connect jumper cables?
The final connection can make a small spark, and batteries can release explosive hydrogen gas, so the last clamp is grounded away from the battery.
| Step | Connect | Disconnect |
|---|---|---|
| 1 | Red clamp to dead battery positive (+) | Black clamp from ground point on the dead car |
| 2 | Red clamp to good battery positive (+) | Black clamp from good battery negative (−) |
| 3 | Black clamp to good battery negative (−) | Red clamp from good battery positive (+) |
| 4 | Black clamp to bare metal on the dead car | Red clamp from dead battery positive (+) |
Some guides, including AAA Colorado, attach the good battery’s positive terminal first. Both agree that the last black clamp goes on bare metal on the dead car, not on the dead battery’s negative terminal. AAA Colorado adds that positive terminals are usually larger, and that clamps should not touch until all four are removed.
Safety checks before you start
- Inspect the battery. AAA says a cracked or bulging case, or a strong rotten-egg smell, means the battery must be replaced, not jumped.
- Match the voltage. Confirm both vehicles use a 12-volt battery. A 24-volt commercial truck system can damage a car’s electronics.
- Never jump a frozen battery. AAA warns that this can cause serious damage to the car and injure people nearby.
- Protect yourself. Wear safety glasses and gloves, and remove rings, watches and other metal jewelry.
- Unplug devices. AAA Colorado says a jump can send a voltage spike that damages phones and other plug-in gadgets.
- Use good cables. AAA recommends a heavy-duty set of six-gauge, 16-foot cables.
How long to let the car run after a jump start
The alternator, not the jump, recharges the battery. Consumer Reports says to let the car run for at least 20 minutes, and AAA says a continuous drive of 20 to 30 minutes is usually enough. Keep the air conditioner and rear defroster off during that drive.
If the engine cranks slowly, AAA suggests charging for another five minutes before retrying. AAA Colorado advises cranking for no more than 20 seconds, then waiting two minutes.
How to jump start a car with a battery pack
A portable jump starter lets you start a car without a second vehicle. Popular Mechanics explains that most units have built-in protection that will not send power if the clamps are connected backward. The general steps are:
- Make sure the jump starter is charged, and read its manual.
- With the ignition off, connect the red clamp to the positive terminal.
- Connect the black clamp to the negative terminal or to the ground point the device manual specifies.
- Check the unit for warning lights, switch it on if required, and start the engine.
- Disconnect the black clamp first, then the red, and let the engine run.
Popular Mechanics says 400 to 600 peak amps suits most vehicles; large SUVs, trucks and RVs may need more. Capacity is often listed in milliamp-hours; see our explainers on what mAh means on a battery and how to convert mAh to Wh. Consumer Reports notes that units rated for 140-degree temperatures cost under $100. Most packs use lithium batteries, so check the rules on lithium batteries in checked luggage before flying with one.
Can you jump start a hybrid or electric car?
Consumer Reports points out that every car, including an electric vehicle, relies on a 12-volt battery to start. Popular Mechanics says a drained 12-volt battery can keep an EV from starting even when the main battery has charge, and the EV must be unplugged from any charger before you jump it. If you drive an electric vehicle such as the 2027 Mitsubishi Eclipse Sportback EV, follow the jump point shown in its manual.
AAA warns that most hybrid and electric vehicles have complex electronics that can be destroyed by jump-starting another car. Do not use one as a donor unless its manual allows it.
Why won’t my car jump start?
- Poor connection. AAA says this is the most common reason. Scrub corroded terminals with a wire brush and reattach the clamps.
- Damaged cables. Frayed or corroded cables may not carry enough current.
- A worn-out battery. If the car still will not start after a third try, the battery has likely failed.
- A single click. One click with bright dashboard lights often points to a bad starter motor. Rapid clicking generally indicates a battery problem.
- The car dies again soon after. If it starts but stalls after a short drive, the alternator is probably not charging the battery.
If these checks do not help, call for roadside assistance.
Why batteries die in cold weather
According to AAA Northeast, an engine needs about 30% more energy to start at freezing, and at zero degrees Fahrenheit a battery can deliver only about 50% of its rated capacity. A fully discharged battery can freeze at 32 degrees.
Car batteries typically last three to five years. Consumer Reports recommends an annual load test once a battery is 2 years old in warm climates or 4 years old in cold climates.
Frequently asked questions
What order do you connect jumper cables?
Connect red to the dead battery’s positive terminal, red to the good battery’s positive terminal, black to the good battery’s negative terminal, and the last black clamp to bare metal on the dead car. Remove them in the reverse order.
How long should you let a car run after a jump start?
Consumer Reports says to let the car run for at least 20 minutes, and AAA says a continuous drive of 20 to 30 minutes is usually enough to recharge the battery.
How long does it take to jump a car?
AAA says the whole process typically takes about 10 to 15 minutes, including three to five minutes of charging before the first attempt to start the dead car.
Why won’t my car jump start?
The most common cause is a poor connection, often from corrosion on the terminals. A worn-out battery, damaged cables, a failing starter or a bad alternator can also prevent a successful jump.
Can you jump start a hybrid car?
Check the owner’s manual first. AAA warns that most hybrid and electric vehicles have complex electronics that can be destroyed by jump-starting another car, so many should not be used as the donor vehicle.
Sources
- AAA: How to Jump a Battery and Get Yourself Back on the Road
- AAA Colorado: Jump Starting a Car
- Consumer Reports: How to Jump-Start a Car With a Dead Battery
- Popular Mechanics: How to Use a Portable Jump Starter
- AAA Northeast: Maintaining Your Car Battery in the Winter
Featured image: “NOCO 12-Volt Car Battery Clips – Car Jumper Cable” by Tony Webster, CC BY 2.0, via Wikimedia Commons. Resized.
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