Key takeaways
Clamp red to the dead battery's positive, red to the good battery's positive, black to the good battery's negative, then the last black clamp to bare metal on the dead car, away from the battery. Run the donor car for 3 to 5 minutes, start the dead car, remove the clamps in reverse order and drive for 20 to 30 minutes.
- 01Never jump a battery that is cracked, swollen, leaking or frozen, and never connect a 12-volt car to a 24-volt system.
- 02Crank for 10 seconds or less per try. If the car still won't start after three tries, the battery or another part likely needs replacing.
- 03Most hybrids and EVs can take a jump to their 12-volt battery, but most should never be used to jump another car.
- 04A short drive won't fully recharge a deeply drained battery, so put it on a charger or have it tested soon.
This guide belongs to our Car maintenance guide: battery and electrical section, which covers the wider topic.
A dead battery usually gives itself away. You turn the key or press the start button and get a slow, groaning crank, a fast clicking, or dash lights that flicker and fade. When that happens, a jump start gets most cars running again in about 10 to 15 minutes, according to AAA's step-by-step jump-start guide.
The job itself is easy. The part that matters is the order of the clamps and a few safety checks. Get those right and you avoid sparks near the battery, blown fuses and damage to the electronics. This guide is for U.S. drivers with a 12-volt car, SUV or pickup. It covers jumper cables, portable jump packs, hybrids and EVs, and what to do when the car still won't start.
Here is the short version. Clamp red to the dead battery's positive post, red to the good battery's positive, black to the good battery's negative, then the last black clamp to clean, unpainted metal on the dead car. For battery voltages, life spans and warning signs, see the battery and electrical section of our car maintenance guide.
Jumper Cable Order and Timing at a Glance
Connect the clamps in this order and remove them in exactly the reverse order.
| Step | Clamp | Where it goes | Which car |
|---|---|---|---|
| 1 | Red (+) | Positive terminal or positive jump post | Dead car |
| 2 | Red (+) | Positive terminal | Donor car |
| 3 | Black (−) | Negative terminal | Donor car |
| 4 | Black (−) | Bare, unpainted metal away from the battery | Dead car |
Connection order from AAA's jump-start guide and the 2018 Mazda CX-5 owner's manual.
Timing matters as much as order. Most failed jumps come from trying too soon or cranking too long.
| Stage | How long |
|---|---|
| Donor car running before the first try | 3 to 5 minutes |
| Each attempt to start the dead car | 10 seconds or less |
| Pause between attempts | 10 to 15 seconds, or about 5 minutes if it cranks slowly |
| Cables left on after the car starts | 3 to 5 minutes |
| Drive afterward to recharge | 20 to 30 minutes |
Timing from AAA's jump-start guide. Cranking limits from the 2022 Ram 2500/3500 owner's manual.
What You Need Before You Start
You need jumper cables and a second vehicle with a healthy 12-volt battery, or a charged portable jump starter.
- Jumper cables, ideally heavy-duty 6-gauge or thicker and at least 16 feet long
- A donor vehicle with a 12-volt battery of similar or larger size
- Safety glasses and insulated gloves
- A flashlight, never a lighter or match
- A wire brush for corroded terminals
- Your owner's manual, which shows the jump points for your model
How to choose jumper cables
Cable gauge numbers run backward. The lower the number, the thicker the wire and the more current it can carry. AAA recommends heavy-duty 6-gauge cables 16 feet long and warns that thin cables fail, especially on V6 and V8 engines and in below-freezing weather. Kelley Blue Book's jump-start guide suggests 4- or 6-gauge cables between 16 and 20 feet long and says to skip 10-gauge sets.
Check your cables before you need them. AAA notes that old or cheap cables can corrode inside the insulation and limit current even when they look fine. Frayed wire, exposed copper or loose clamp jaws mean it's time for a new set.
Picking a donor vehicle
Both vehicles must run on 12 volts with a negative ground. Mazda's owner's manual warns that a 24-volt supply, such as two 12-volt batteries wired in series or a 24-volt generator, can permanently damage the starter, ignition system and other electrical parts. AAA gives the same warning about 24-volt commercial truck systems.
A gas car or truck makes the best donor. AAA says most hybrids and electric vehicles have complex electronics that can be destroyed by jump-starting another car, so check the manual before you offer one as the donor.
Time, Difficulty and When to Call for Help
A jump start is a beginner job that takes about 10 to 15 minutes from opening the hoods to driving away.
| Item | Detail |
|---|---|
| Difficulty | Easy |
| Time | About 10 to 15 minutes |
| Call for help instead if | The battery is damaged or frozen, traffic is close, or it's too dark or foggy to see |
Time estimate and conditions from AAA's jump-start guide.
Safety Checks Before You Touch a Clamp
Look at the dead battery before you connect anything.
Do not jump the battery if you see or smell any of these:
- Cracks in the case or bulging, swollen sides
- Leaking fluid or heavy, crusty corrosion
- A rotten-egg smell, which AAA says signals leaking sulfuric acid and hydrogen gas
- A low fluid level on a battery with removable caps
Kia's owner's manual warns against jumping a battery that is frozen or low on electrolyte, because it may rupture or explode. It also says to wear protective glasses, since battery acid is poisonous and corrosive.
Protect yourself too. Take off rings and watches, which AAA says can cause burns or short circuits, keep flames and cigarettes away, and don't lean over the battery while you connect the cables.
Never jump a frozen or damaged battery
A frozen, cracked or swollen battery can rupture or explode during a jump. Don't connect anything to it. Step away and call a tow or a mobile battery service.
Why a dead battery can freeze
A charged battery resists freezing, but a drained one does not. AAA Northeast says a fully discharged battery, at just under 12 volts, can freeze at 32°F, while a fully charged battery would need temperatures below minus 76°F.
Consumer Reports quotes AAA's David Bennett warning that jumping a damaged or frozen battery could cause significant damage to the vehicle and to the people around it.
How to Jump Start a Car With Jumper Cables
If your owner's manual gives a different jump point or order, follow the manual.
- Park the donor car close, but not touching. Leave a few inches of air between the cars, put both in Park (or Neutral for a manual), set both parking brakes and turn both ignitions off.
- Switch off everything electrical. Headlights, radio, climate control and plug-in accessories, in both vehicles.
- Open both hoods and find the terminals. The positive post is marked + and usually has a red cover. The negative is marked −.
- Check and clean the terminals. White, green or blue crust blocks current. Kelley Blue Book says to scrub it off with a wire brush, not your bare hand, because corrosion can irritate skin.
- Clamp one red end to the dead battery's positive (+) terminal. Wiggle it so the teeth bite bare metal.
- Clamp the other red end to the donor battery's positive (+) terminal.
- Clamp one black end to the donor battery's negative (−) terminal.
- Clamp the last black end to bare metal on the dead car. Pick a thick, unpainted bolt or bracket on the engine, away from the battery and fuel lines. Kia names the engine lifting bracket as one example. Never put this clamp on the dead battery's negative post.
- Route the cables away from fans and belts. Hyundai's owner's manual tells drivers to stay clear of fans and moving parts in the engine bay even when the engines are off.
- Start the donor car and let it run for 3 to 5 minutes. AAA says holding its engine slightly above idle helps, especially on cold mornings.
- Try to start the dead car. Crank for no more than 10 seconds. If it cranks slowly, wait about five minutes and try again. Stop after the third failed try.
- Leave the cables on for 3 to 5 more minutes once it runs.
- Remove the clamps in reverse order. Take black off the ground point, then black off the donor, red off the donor and finally red off the car you jumped. Don't let the clamps touch each other or any metal.
- Drive for 20 to 30 minutes. AAA suggests keeping the air conditioner and rear defroster off so more of the alternator's output goes into the battery.
Can't find the battery? Look for a jump post
Some cars put the positive jump point in the under-hood fuse box or under a front panel instead of on the battery itself. Kia, Hyundai and Tesla manuals all show one. Use it whenever your manual says to.
Why Does the Clamp Order Matter?
The order keeps the one spark you can't avoid away from the battery, and it keeps a live clamp from shorting against the car.
A lead-acid battery gives off hydrogen gas during normal use, and Mazda's manual warns that a spark near the battery can ignite it and make the battery explode. Completing a circuit usually makes a small spark at the last connection, so you make that connection on the engine block, away from the battery.
Positive-first protects you in a different way. While only the red clamps are on, a red clamp that slips against a fender completes no circuit. Once a black clamp is grounded, the same slip is a direct short across the donor battery, which is why Mazda also warns against letting the positive terminal touch the body.
Skipping the ground point causes its own damage. Kia's manual says connecting the donor's negative directly to the dead battery's negative can overheat and crack the discharged battery and release acid. Hyundai's manual adds that a spark at that terminal could cause an explosion.
Removal order matters too. Kelley Blue Book says pulling the cables off in the wrong order can cause sparks, an electrical surge or blown fuses. Consumer Reports' Paolo Fu warns that the wrong procedure can fry a key electronic component, and AAA's David Bennett says following the owner's manual is crucial to avoid hundreds or thousands of dollars in repairs.
Using a Portable Jump Starter
A portable jump starter takes the place of the donor car.
Consumer Reports describes these packs as a paperback-sized backup battery. They usually hold a charge for months, and models designed to tolerate 140°F can cost under $100.
- Check that the pack is fully charged.
- Turn off the car's ignition, lights and accessories.
- Clamp the pack's red lead to the positive terminal or jump post.
- Clamp the black lead to a solid ground point on the car, unless the pack's instructions say otherwise.
- Set the pack on the ground, not on the engine, where it could fall when the engine starts.
- Switch the pack on and start the car.
- Once the engine runs, switch the pack off and remove the black clamp, then the red.
The tip about keeping the pack off the engine comes from the RAC's jump-start guide. Pack designs differ, so read your pack's instructions once before you need them.
Not every pack is equal. Our accessories guide's safety and emergency gear section explains why cranking current is a better comparison than peak amps, and why a pack certified to UL 2743 is worth the search.
UL 2743 is the safety standard for portable power packs. It covers packs with a booster function that give emergency starting power to vehicle batteries rated at 24 volts DC or less.
Can You Jump a Hybrid or Electric Car?
Yes, in most cases you can jump the 12-volt battery in a hybrid or EV. Most should never be used to jump another car.
Consumer Reports points out that every drive begins with a 12-volt battery, even in an electric vehicle. Kelley Blue Book says hybrids carry both a 12-volt auxiliary battery and a high-voltage battery, and some have jump-start tabs in the under-hood fuse box. You only ever connect cables to the 12-volt side.
What the manuals say
Hyundai's 2026 plug-in hybrid manual has you connect to a red positive jumper terminal and a chassis ground, press a 12V Battery Reset switch, then start and stay in ready mode or drive for 30 minutes in total. It warns that using the hybrid to jump another vehicle damages its lithium 12-volt battery.
Tesla's Model 3 owner's manual puts the positive jump post under a maintenance panel at the front and uses a bolt next to the brake fluid reservoir as ground. It calls for a low-voltage source such as a portable jump starter and states that a Model 3 cannot be used to jump start another vehicle. Kelley Blue Book adds that you can't jump an EV with another EV, even one of the same brand.
| Vehicle | Can it get a jump? | Can it give a jump? | Where to connect |
|---|---|---|---|
| 12-volt gas car, SUV or pickup | Yes | Yes, if its battery is healthy | Battery terminals or remote jump post |
| 2026 Hyundai plug-in hybrid | Yes, then press 12V Battery Reset | No | Red jumper terminal and chassis ground |
| Tesla Model 3 | Yes, from a jump pack or other low-voltage source | No | Jump post under the front maintenance panel and ground bolt |
| Another EV as the donor | No | No | Not applicable |
From the Hyundai and Tesla owner's manuals, Kelley Blue Book and AAA. Your own manual is the final word for your model.
Cold Weather, Rain and Roadside Conditions
Cold weather is hard on batteries, and it changes how you do a jump. The AAA Automotive Research Center reports that a battery loses about 35 percent of its strength at 32°F and about 60 percent at 0°F. On those mornings, an engine can need up to twice the normal current to start.
In the cold, give the donor car the full five minutes and hold its engine slightly above idle, as AAA suggests. Thick cables matter most on frozen mornings.
Rain is less of a problem than most people think. Kelley Blue Book says jumping a car in the rain is safe, because a car battery's voltage is low. Traffic is the bigger danger: on a narrow shoulder or a blind curve, stay somewhere safe and call a roadside service.
Why Won't the Car Start After a Jump?
The sound the car makes when you turn the key is the best clue.
| What you hear or see | Likely cause | What to do next |
|---|---|---|
| Rapid clicking | Battery still too weak | Check the clamps, let the donor run longer, try again |
| One sharp click with bright dash lights | Starter | Stop jumping and have the starter checked |
| Slow crank that gets stronger | Weak battery taking charge | Wait about 5 minutes and try again |
| Starts, then dies within 10 to 15 minutes | Alternator | Have the charging system tested |
| No start after three tries | Battery can't hold a charge, or another fault | Test or replace the battery, or call for help |
From AAA's jump-start guide and AAA's bad alternator vs. bad battery guide.
Check the simple things first. Consumer Reports says to check the connections and tighten or clean them. A clamp sitting on paint, plastic or a greasy bolt can look connected and still pass very little current.
The AAA alternator vs. battery guide says a car that starts with a jump but stalls within 10 to 15 minutes points to the alternator. A car that needs jump after jump points to a failing battery.
If the battery and cables check out and the engine still won't crank, our guide to what to do when a car won't start walks through the starter, fuel, key fob and immobilizer causes.
Free tool
Car Symptom Diagnosis Tool. Pick "Car won't start" to see the likely causes, what to check first and how urgent the problem is.
Mistakes That Damage Cars or Hurt People
Most jump-start damage comes from a handful of repeat mistakes.
- Putting the last black clamp on the dead battery's negative post. It risks a spark at the battery and, per Kia, a cracked case.
- Letting the clamps touch. Kia's manual says touching cables can cause sparks.
- Jumping a frozen, cracked or swollen battery. It can rupture or explode.
- Using a 24-volt source on a 12-volt car. It can permanently damage the starter and ignition.
- Cranking for long stretches. The Ram manual limits each try to 10 seconds to protect the starter.
- Using a hybrid or EV as the donor. Hyundai and Tesla both say not to.
- Push-starting a car with an automatic transmission. The Ram owner's manual says automatic vehicles can't be started this way. Hyundai tells owners not to push-start at all.
- Counting on the idle to recharge the battery. It adds little charge, as the next section explains.
After the Jump: Recharge and Test the Battery
A jump start gets you moving. It doesn't repair or fully recharge the battery.
AAA recommends driving for 20 to 30 minutes. AutoZone's charging guide suggests at least 30 minutes, ideally at highway speeds. It warns that a 30-minute idle in the driveway won't do much, and that a seriously drained battery can need several hours of driving to get close to full.
A charger does the job better. In a battery maker's explainer, OPTIMA Batteries says alternators are designed to maintain a battery that is near full charge, not to recharge a deeply discharged one. Using the alternator that way can wear it out early.
Interstate Batteries adds that a jump-started battery may never reach a full charge unless a charger is used.
Have the battery tested soon, even if the car seems fine. AutoZone says free battery testing is available at every AutoZone in the U.S., and that its fast charger can charge most car batteries in about 30 minutes. AAA's guide says a battery more than three years old, or one that has been struggling, should be tested at a shop rather than trusted to a short drive.
A multimeter gives a quick read at home. Measure across the terminals with the engine off, then running.
| Reading | What it means |
|---|---|
| 12.6 volts or higher, engine off | Fully charged |
| 11.9 volts or lower, engine off | Dead |
| 13.7 to 14.7 volts, engine running | Alternator is charging |
Voltage ranges from Interstate Batteries' support FAQs.
Watch the dash on the drive home. A red battery or charging light means the charging system has stopped charging, and our list of dashboard warning lights explains what to do next.
One deep drain can shorten a battery's life. AAA's battery warning signs guide says a battery that goes completely dead can lose a significant part of its life span even after it is recharged. It puts the usual replacement interval at three to five years, with a yearly test after the third year.
What a Jump Start Costs: DIY, Jump Pack or Repair
Jumping a car yourself costs nothing if you own cables. The real bill comes when the jump shows a failing battery, starter or alternator.
| Option | Typical cost | Notes |
|---|---|---|
| Your own cables and a donor car | $0 | Cables are a one-time buy |
| Portable jump starter | Under $100 for heat-tolerant models | Works without a second car |
| Battery test and charge at AutoZone | Free | Most batteries charge in about 30 minutes |
| New car battery | $45 to $250, sometimes more | Price depends on battery type |
| Starter replacement, installed | $350 to $1,100 | Labor time varies by engine layout |
| Alternator replacement | $500 to $2,500 | Includes parts and labor |
Jump starter price from Consumer Reports, testing from AutoZone, battery and alternator ranges from AAA's bad alternator vs. bad battery guide, starter range from AAA's starter cost guide. Kelley Blue Book says a battery can run $250 or more.
The starter figure comes from AAA's starter replacement cost guide, which puts labor in its network at $150 to $300 an hour. Ask any shop to split the quote into parts and labor hours.
Our repair cost estimator turns those numbers into a total and shows what you would save by doing the work yourself.
AAA members can call AAA Roadside Assistance for a jump, and AAA's Mobile Battery Service can test and replace a battery at your home or workplace.
A good jump comes down to three habits: the right clamp order, short cranking bursts and a proper recharge afterward. Keep decent cables or a charged jump pack in the car, find your jump points in the manual once, and have the battery tested after any jump. AAA lists frequent jump starts as one of the clearest signs a battery is near the end of its life.
Frequently Asked Questions
How long should jumper cables stay on before you start the dead car?
AAA recommends letting the donor car run for three to five minutes before the first attempt, which gives the dead battery a small charge to work with. Once the car starts, leave the cables connected for another three to five minutes, then remove them in reverse order. In very cold weather, use the full five minutes and keep the donor engine slightly above idle.
Can a car battery be too dead to jump start?
Yes. AAA notes that a jump cannot revive a battery that is too old to hold a charge. If the car still will not start after a third try, the battery most likely needs replacing. A frozen, cracked or swollen battery should never be jumped at all, because it can rupture or explode. Call a tow or a mobile battery service instead.
Is it safe to jump start a car in the rain?
Kelley Blue Book says it is safe to jump start a car in the rain, because a car battery runs at low voltage. The bigger risks are slipping, poor visibility and passing traffic. Keep the clamps clean, make sure each one grips bare metal, and move somewhere safer or call roadside help if visibility is poor or you are close to traffic.
Why does my car die again soon after a jump start?
If the car starts with a jump but stalls within about 10 to 15 minutes, AAA says the alternator is the likely cause, because it is not recharging the battery. If the car runs fine but needs another jump the next morning, the battery is probably failing. A battery and charging system test at a parts store or repair shop will tell you which one it is.
Does AutoZone test and charge car batteries for free?
AutoZone says free battery testing is available at every AutoZone store in the United States, and that its fast charger can charge most automotive batteries in about 30 minutes. A test after a jump start shows whether the battery can still hold a charge, which tells you whether to replace it now or keep using it and recheck it later.
Can jump starting damage a car's computer or electronics?
It can if the job is done wrong. Kelley Blue Book says connecting or removing the cables in the wrong order can cause sparks, an electrical surge or blown fuses. Consumer Reports warns that an improper procedure can fry a key electronic component. Following the clamp order, keeping the clamps apart and checking the owner's manual for jump points avoids most of these problems.
Sources and References
- AAA. How to Jump a Battery and Get Yourself Back on the Road
- AAA. Know When to Replace the Car Battery: 8 Key Warning Signs
- AAA. Bad Alternator vs. Bad Battery: A Quick Guide
- AAA. How Much Does a Starter Replacement Cost?
- AAA Hudson Valley. Cold Weather Is Hard on Your Car Battery: Here's What to Know
- AAA Northeast. Maintaining Your Car Battery in the Winter
- Consumer Reports. How to Jump-Start a Car With a Dead Battery
- Kelley Blue Book. How to Jump-Start a Car in 6 Steps
- Mazda USA. 2018 Mazda CX-5 Owner's Manual: Battery Runs Out
- Kia. 2022 Kia Owner's Manual: Jump Starting
- Hyundai. 2026 Hyundai Plug-in Hybrid Owner's Manual: Jump Starting
- Tesla. Model 3 Owner's Manual: Jump Starting
- Mopar (Ram). 2022 Ram 2500/3500 Owner's Manual: If Engine Fails to Start
- RAC. How to Jump Start a Car in 10 Steps
- Standards Council of Canada. ANSI/CAN/UL 2743: Portable Power Packs
- OPTIMA Batteries. Fact: Alternators Are Not Designed to Charge Dead Batteries
- Interstate Batteries. Support FAQs
- AutoZone. Free Battery Testing & Installation Services
- AutoZone. How Long Do You Need to Drive to Charge Your Car Battery
Written by
CarTipsMentor Team
Researched from the sources listed above and checked against them before publishing. Nobody paid to be mentioned on this page. It is general information, not advice about your own vehicle.
Published . Last updated .
