Dead car battery: what to do

Cables, a jump starter or a call: all three work.

The answer in 2 lines. A dead battery can usually be jump-started with jumper cables from another car or with a portable jump starter. Follow your owner's manual exactly: many newer cars have special jump points under the hood. Turn everything off first, keep flames and sparks away, and never touch a battery that is cracked, bulging, leaking or frozen. If you're unsure, the car is a hybrid or EV, or you're on a highway shoulder, call roadside assistance. Afterward, drive for a while and get the battery and charging system tested.

The first 3 steps

Turn everything off: headlights, radio, heater or AC, phone chargers.
Open the owner's manual to the jump-starting section and find the connection points; on many cars the positive post is under a cover, and some batteries are in the trunk or under a seat.
No flames, cigarettes or sparks near the battery.

Stop: danger

Battery cracked, bulging, leaking or frozen: don't touch it and don't try to jump it. Call roadside assistance.
Rotten-egg smell near the battery: it may be overheating. Step away and call for help. Battery acid on skin or in the eyes: rinse with running water for at least 15 minutes and get medical help.
Stuck on a highway or busy road: hazard lights on, and get well away from traffic if you can do so safely, or stay buckled in if you can't. Call roadside assistance, or 911 if you're in a travel lane or in danger.

The signs

The engine cranks slowly or you only hear rapid clicking.
Dash and dome lights are dim or don't come on.
Lights left on overnight, a car parked for weeks, lots of short trips in cold weather: the battery can't recharge. NHTSA advises having the battery checked before winter, when cold reduces its power (NHTSA winter driving tips).
Battery warning light on while driving: often a charging (alternator) problem; get it checked soon.
Not sure it's the battery? See our guide on dead battery or bad starter.

Jump-starting with cables or a jump starter

Every car has its own connection points and order. Follow your owner's manual exactly. The usual method:

Both batteries must be the same voltage (12 V for most cars). The cars must not touch each other. Both ignitions off.
Red clamp to the positive (+) of the dead battery, the other red clamp to the positive of the good battery; black clamp to the negative (−) of the good battery, then the last black clamp to unpainted metal on the dead car's engine block or the manual's ground point, away from the battery. Never let red and black clamps touch.
Start the working car, wait a few minutes, then try yours. Remove the clamps in reverse order.
Choosing cables: heavy-gauge (a lower gauge number means thicker wire, such as 4 or 6 gauge) and long enough to reach between two cars, 12 to 20 feet. Thin, cheap cables may not carry enough current.
Choosing a portable jump starter: check that it's rated for your engine size and fuel type (larger engines and diesels need more power), and keep it charged; CTEK's guide explains the ratings. With a jump starter, you don't need a second car.
Hybrid or electric car: don't do anything without the manual. Many can't be used to jump another car, and some have a small 12 V battery in an unusual place. Call roadside assistance if in doubt.

Calling for help

Roadside assistance may already be included with your car insurance, your new-car warranty, a credit card, or a motor club such as AAA (many AAA clubs offer mobile battery testing and replacement). Check your insurer's app or your warranty booklet before paying for a tow.
No coverage: a local towing or mobile battery service can come, at a price; ask for the total cost on the phone before they come.
On the roadside, drivers in every state must slow down or move over for emergency and service vehicles; some states also protect any stopped car with hazard lights (NCSL).

What not to do

Push-starting an automatic or a modern car: it doesn't work on automatics and isn't advised on many others. Check the manual.
Turning the engine off right after the jump: drive for at least 20 to 30 minutes so the alternator can recharge the battery a bit.
Throwing the old battery in the trash.

After the jump

Get the battery and charging system tested: many auto parts stores do it free.
If it dies again, it likely needs replacing. Cars with start-stop often need a specific type (AGM or EFB): check the manual.
A new battery that fails early: check the free-replacement period in the battery's warranty and keep your receipt.

The old battery: never in the trash

Car batteries contain lead and acid and must be recycled. When you buy a new one, stores usually charge a refundable core charge that you get back when you return the old battery (how the core charge works). Many states require battery sellers to take back used lead-acid batteries; New York's Environmental Conservation Law §27-1701 is one example. Auto parts stores and most household hazardous waste sites accept them: Battery Council International explains where to take yours.

Good to know

Cold weather and long periods without driving drain batteries: if a car sits for weeks, a battery maintainer (trickle charger) keeps it topped up.
Carry jumper cables or a charged jump starter in winter, along with a flashlight and gloves.
Clean white or green corrosion on the terminals only with the engine off, gloves and eye protection on; see the WVU lead-acid battery safety sheet.

On a January morning in Minneapolis, Tom's car only clicks. He finds the jump points in the manual, and his neighbor connects the cables in the right order. The car starts; Tom drives 30 minutes to an auto parts store, where the battery fails the free test. He buys a new one, returns the old battery and gets his core charge back.

A made-up story, for illustration.

Bobby

Sources, verification, confidence

Verified on November 1, 2026, for the United States. Confidence: high for safety (sparks, acid, damaged batteries) and recycling; medium for roadside help and battery take-back, which depend on your coverage and your state. This guide describes common cases, not a diagnosis.