How to Jump Start a Car Safely

This guide is for drivers whose car won't start and who have jumper cables, a portable jump pack, or a donor car nearby. It helps you get going without hurting yourself or damaging either vehicle. It also tells you when to stop and call a professional.

Short answer

Check your owner's manual first. It lists the correct terminals, ground point, and sequence for your car, and it overrides any generic instructions. If your manual doesn't say otherwise, connect red to the dead battery's positive terminal, red to the donor's positive, black to the donor's negative, and the last black clamp to unpainted metal on the dead car, away from the battery. Start the donor, wait a few minutes, start your car, then remove the clamps in reverse order.

A portable jump pack works differently and needs its own instructions. Stop and call for help if the battery is damaged or frozen, you can't identify the right connection points, or the car is an unfamiliar hybrid or EV.

Do you actually need to do this?

A jump helps only when a drained battery is the problem. A jump pack should start the car if so, according to Interstate Batteries. If the car still won't start after a correct jump, the battery may not be the cause, and repeating attempts won't tell you which part failed.

Signs a jump is worth trying:

• The car won't crank, cranks slowly, or the dashboard is dim, and the battery looks undamaged.
• You have a working donor car or a charged jump pack.
• You can work safely, away from traffic.

Signs to skip it:

• The battery is cracked, swollen, leaking, damaged, or frozen.
• You can't find the correct terminals or ground point.
• The car is a hybrid or EV and you haven't read the 12-volt jump procedure in its manual.

When a lighter fix is enough: if you have a charged jump pack, it can be faster than finding a donor car. A jump starter typically takes under a minute to start a car.

What you need

• Jumper cables with four clamps (red for positive, black for negative), or a charged portable jump starter with its manual.
• A donor car with a healthy 12-volt battery. It must be the same system voltage as yours.
• Your owner's manual. Look in the emergency section.
• Safety glasses and gloves, if you have them. Take off rings, bracelets, and other jewelry.
• Time: about 10 to 15 minutes, including a 3 to 5 minute charging wait, according to AAA.
• Cost: nothing extra if you already own the cables or pack and have a willing donor.

If you keep a kit in the trunk, check the cables and pack whenever you run through your routine replacement schedule for household and car items, so a worn clamp or an uncharged pack doesn't surprise you on the day you need it.

Step-by-step

Step 1: Read the manual and set up both cars

Open the emergency section of your manual and follow it where it differs from this guide. Then park the cars so the cables reach both batteries. Put both in park (or neutral for a manual), set the parking brakes, and turn both ignitions off. Switch off headlights, dome lights, and the radio, per AAA Colorado.

Done right: both cars are off, stationary, and every accessory is dark.

Step 2: Clamp red to the dead battery's positive terminal

Find the terminal marked + and attach one red clamp. Wiggle it until the grip feels tight, as AAA Northeast advises. A loose clamp gives a poor connection.

Done right: the clamp stays put when you tug it gently.

Step 3: Clamp the other red end to the donor's positive terminal

Attach it to the + terminal on the good battery. Keep the clamps from touching each other or any metal.

Done right: both red clamps are on + terminals, and the black clamps are still loose and apart.

Sequence note: AAA Colorado lists the donor's positive terminal first, while Interstate Batteries and other AAA pages start at the dead battery. Either way, all four clamps end up in the same places. Your manual's order wins if it specifies one.

Step 4: Clamp black to the donor's negative terminal

Attach one black clamp to the - terminal of the good battery.

Done right: three clamps are on, and the last black clamp hangs free without touching anything.

Step 5: Clamp the last black clamp to unpainted metal on the dead car

Pick bare metal such as a thick bolt on the engine block or the alternator mounting bracket, as far from the battery as possible. Don't use the dead battery's negative terminal. AAA Oregon warns this can create a spark and cause an explosion. If your manual names a specific ground point or jump post, use that instead.

Done right: the clamp bites bare metal and sits clear of belts and fans.

Step 6: Start the donor car and wait

Start the donor and let it run. AAA's guidance ranges from at least one minute to a couple of minutes. Another AAA page recommends three to five minutes for a deeply drained battery.

Done right: the donor idles smoothly while the cables stay in place.

Step 7: Start the dead car

Crank for no more than 20 seconds. If it doesn't start, wait two minutes before trying again. If it cranks but won't catch, it may need more charging time first.

Done right: the engine runs on its own.

Step 8: Remove the clamps in reverse order

Take off the black clamp from the ground point, then the black clamp from the donor, then the red from the donor, and finally the red from the started car. Never let clamps touch while any are still connected. Keep your hands clear of fan blades and belts.

Done right: all four clamps are off, cables are stowed, and the engine is still running.

Before you start: safety checks and when NOT to jump

Run through these before touching a clamp:

• Inspect the battery. Never jump a damaged or frozen battery, per the Interstate Batteries manual. If it looks cracked, swollen, or leaking, treat it the same way and stop.
• Match the voltage. A booster must match the vehicle's system voltage. An NHTSA-hosted service bulletin warns that the wrong voltage may cause explosion or fire. Don't apply a 12-volt procedure to an unfamiliar 24-volt system.
• Keep clamps apart. Don't let them touch each other or the car.
• Protect yourself. Remove jewelry, and wear glasses and gloves if you have them.
• Work somewhere safe. If you can't stay clear of traffic, don't do this here.

Stop and call a professional if:

• The battery is frozen or visibly damaged.
• You can't identify the correct posts or ground point.
• Your manual prohibits jump-starting or gives a different procedure you can't follow.
• It's a hybrid or EV and the 12-volt procedure isn't clear.
• You smell or see anything that makes the battery feel unsafe to touch.

Is it really the battery? Quick symptom check

A jump that works points to a drained battery. A jump that doesn't work doesn't tell you what failed. A drained battery might have simply been left on, or it might be failing, or something else in the charging system might be at fault.

• Car starts with the jump, then dies or won't restart later: get the battery and charging system tested instead of jumping again and again.
• Cranks but won't start after a jump: wait for more charging time, then try once more within the 20-second limit.
• Still dead with correct connections: stop and arrange roadside or professional diagnosis.

Jump start with a portable jump starter (no second car)

A jump pack skips the donor car, but the pack's own instructions control the process. Read them first and know what each indicator light means.

1. Take off jewelry and put on glasses and gloves if available.
2. Confirm the pack is fully charged. Find its positive (usually red, marked +) and negative (usually black, marked -) clamps.
3. Per Interstate Batteries, attach the red clamp to the battery's positive terminal, then the black clamp to the negative terminal. Some packs or manuals call for a different ground point, so follow yours. If the pack has no light, you may need to switch it on.
4. Set the pack where it can't fall into the engine bay or touch moving parts. Wait a moment, then start the car.
5. If the car doesn't start on the first try, don't try again right away. You could damage the pack or the starter. Disconnect, check the pack's charge, and recharge it if it's warm or depleted. If the clamps look corroded or the pack is cold, the connection may be poor.
6. After it starts, disconnect the black clamp first, keep the clamps from touching the battery, and lift the pack away from the engine.

If the pack fails to start the car, recharge it and wait 30 minutes before trying again. A pack can start a car in under a minute, but fully recharging the car's battery can take several hours.

Special cases: hybrids, EVs, start-stop, and hidden batteries

Hybrids and EVs. NHTSA says the high-voltage battery can't be jumped. In most cases the 12-volt battery can be, much like a gas car's, but your manual covers the procedure and the battery's location. Treat exposed high-voltage components and wiring as shock hazards. Some manuals are strict. The Tesla Model Y manual warns that connecting to the wrong jump post or touching leads together can damage the car.

Marked jump points. Some vehicles specify labeled jump points instead of the battery terminals. One NHTSA-hosted bulletin shows four labeled points and warns that placing both clamps correctly is necessary to avoid blowing a fuse. If your manual shows labeled points, use those rather than guessing.

Hidden batteries and other systems. If you can't see the battery, or your car has an unusual setup, rely on the emergency section of your owner's manual. If it isn't available or you can't follow it, call roadside assistance. The same applies to anything that isn't a standard 12-volt system.

If it still won't start: stop and call for help

Call roadside assistance or a professional if:

• Several correct attempts, with sensible waits between them, don't work.
• The car cranks only slowly even with the donor running.
• You find a damaged or frozen battery, or lose confidence about the connections.
• The car starts but stalls again soon after.
• Your pack fails and a 30-minute wait and recharge don't help.

Repeated cranking can also wear your starter, and a dead jump isn't a diagnosis. A shop can test the battery and charging system.

What to do after the jump

• Leave the engine running. AAA Oregon recommends at least 30 minutes, and a short drive helps the alternator charge the battery.
• Don't shut the car off right away to test it. Drive first, as above.
• Get the battery fully charged and tested at a repair shop, as AAA Northeast advises. Driving alone isn't a substitute for testing.
• If the battery is old or failing, it may be time for a replacement. Cold weather strains batteries, so plan ahead if you live somewhere with hard winters.

Common mistakes and why they cause harm

• Clamping the final black clamp to the dead battery's negative terminal. It can create a spark near the battery, and AAA Oregon says it can cause an explosion.
• Letting clamps touch each other or the car. This creates a short circuit that can spark or damage electronics. The Tesla manual explicitly warns about this.
• Using the wrong voltage. The NHTSA-hosted bulletin warns of explosion, fire, injury, or death.
• Jumping a frozen or damaged battery. Interstate's manual says never to do this.
• Cranking past 20 seconds or retrying immediately. AAA says to wait two minutes between tries. A jump pack that fails needs a 30-minute break and recharge. Otherwise you risk damaging the pack or your starter.
• Ignoring the manual. Terminals, jump posts, and sequence vary by model. A wrong connection point can blow a fuse or damage the car.
• Touching fans or belts while removing clamps. Moving parts can injure you.

What to expect afterward

If the jump worked, the engine should idle normally and the dash should look normal. Plan to keep the car running for 30 minutes or more, as AAA Oregon suggests, and to book a battery and charging-system test soon afterward. If you used a jump pack, it needs recharging too. A pack may take several hours to fully recharge.

Warning signs that the problem isn't solved:

• The car won't restart after you shut it off.
• The engine cranks slowly again.
• The car stalls while driving.

Any of these means a professional should check the battery and charging system before you rely on the car.

Frequently asked questions

Why did the car start with a jump but die again later?

A jump only gets the engine running. It doesn't show whether the battery or the charging system is at fault. Have both tested at a repair shop rather than jumping repeatedly.

How soon should I get the battery tested?

Soon after the jump. AAA Northeast advises taking the car to a repair shop to have the battery fully charged and tested once it's running. Drive it there rather than shutting it off first.

Can I jump-start a hybrid or EV?

Usually only the 12-volt battery, not the high-voltage battery, according to NHTSA. Follow your owner's manual for the procedure and battery location, and don't touch exposed high-voltage parts. If the manual isn't clear, call a professional.

Where are my car's jump posts or ground point?

Your owner's manual lists them, usually in the emergency section. Some vehicles use specific labeled points instead of the battery terminals. If you can't find them, don't guess; call roadside help.

Is it safe to drive after a successful jump?

Yes, in most cases. Leave the engine running for at least 30 minutes, ideally by driving, then get the battery tested. If the car stalls or struggles to restart, stop and call for help.

What if it still clicks, cranks slowly, or won't start after the jump?

Check that all four clamps are secure and give the car a few more minutes of charging, as AAA advises. Keep cranks under 20 seconds with a two-minute wait between tries. If it still won't start, stop and call roadside assistance.

Related guides

• How Often Should You Replace HVAC Filters, Smoke Detectors & More?: Offers a replacement-schedule approach to routine upkeep, though it covers home HVAC filters and smoke detectors rather than car batteries.

Next steps

This week, check that your jumper cables or jump pack are in the car and in good shape, and read the jump-start section of your owner's manual so you know where your terminals or jump posts are before you need them, then follow the Jump Starting a Car Checklist as you work.