How to jump-start a car safely, step by step

Is it safe to jump-start the car where it is?

Before you touch the cables, look at where the car is. A jump start usually means two cars parked close together and people working at the front of them, so where you do it matters as much as how. AAA advises against a jump start when there isn't enough room to work clear of traffic, or when darkness or fog makes it hard to see.

In a driveway or a parking lot, you are usually fine. A highway shoulder is a different story. AAA warns never to stand in front of or behind a car stopped along the road, and Texas DPS advises parking as far off the traveled lanes as possible, turning on your flashers and getting out on the passenger side, away from traffic. If you can't get well clear of passing cars, don't do the jump there. If you are stopped in a live lane or anyone is hurt, call 911 first.

What do you need to jump-start a car?

Take off rings, watches and other metal jewelry before you start. Don't use a hybrid or electric vehicle as the donor car. AAA warns that most have complex electronics that can be destroyed by jump-starting another car. Here is what to have ready:

• Jumper cables in good shape. AAA recommends heavy-duty, six-gauge cables about 16 feet long, and the cables should have no frayed wires.
• A donor vehicle with a healthy battery of similar or larger size.
• Safety glasses, to protect your eyes from acid and bits of plastic if a battery vents.
• Gloves, for protection from electric shock and battery acid.
• The owner's manual, if it's handy. Carmakers give jump-start steps for their own vehicles, and some batteries sit under a cover you have to remove first.

Check the dead battery before you connect anything

A damaged battery can be dangerous to jump. Batteries give off hydrogen gas during normal use, and Mazda's owner's manual warns that a spark or flame can ignite it and make the battery explode. Keep cigarettes, open flames and sparks away from the battery the whole time, and don't let metal tools touch the terminals. Do not jump-start the car if any of these are true:

• The battery case is cracked or bulging.
• You smell rotten eggs, which AAA says points to leaking acid and gas.
• The battery fluid is low or the battery is frozen.
• The two vehicles don't both use 12-volt systems. AAA warns that hooking a 24-volt commercial truck system to a car can cause serious damage.

What order do jumper cables go on?

Put both vehicles in park, or in neutral for a manual, and set the parking brakes. Park close enough for the cables to reach, but leave a few inches so the cars don't touch. Turn off both ignitions, the headlights, the radio and other accessories.

The last connection is the one that matters most. It can make a small spark, and putting it on metal away from the battery keeps that spark away from any battery gas. AAA Oregon/Idaho warns that clamping it straight to the dead battery's negative terminal creates a risk of explosion. Keep the cables clear of belts and fans, and don't let the clamps touch each other. Then connect them in this order:

1. One red clamp to the positive (+) terminal of the dead battery.
2. The other red clamp to the positive (+) terminal of the good battery.
3. One black clamp to the negative (-) terminal of the good battery.
4. The last black clamp to bare, unpainted metal on the dead car, such as a thick bolt on the engine block, away from the battery.

How long should the good car run before you try to start?

Start the good car and let it run for three to five minutes. AAA notes that keeping its engine slightly above idle helps it charge faster. Then try to start the dead car and pay attention to what it does:

• It starts quickly: AAA says that suggests a healthy battery that was simply run down.
• It cranks slowly: you are making progress. Let the good car charge it for another five minutes and try again.
• It clicks rapidly: the battery is usually the problem.
• It makes a single click while the dash lights stay bright: AAA says that often points to a bad starter.
• It still won't start after a third try: AAA says the battery has likely failed and needs to be replaced.

How do you take jumper cables off?

Once the car starts, AAA suggests leaving both cars connected and running for three to five minutes. Then remove the cables in the reverse order you put them on, without letting the clamps touch each other or any metal:

1. The black clamp from the bare metal on the car you jumped.
2. The black clamp from the good battery.
3. The red clamp from the good battery.
4. The red clamp from the battery you jumped.

What should you do after the car starts?

AAA recommends driving for 20 to 30 minutes, with the air conditioning and rear defroster off, so the alternator can recharge the battery. If the car starts but dies again after a short drive, the alternator may not be charging. If the battery is more than three years old or has been struggling, have it tested, because a short drive won't save an old battery.

If the jump didn't work, check the simple things first. AAA says a poor connection is the most common reason a jump fails, so make sure each clamp bites into clean, bare metal. Past that, put the cables away. A battery that is damaged, a spot too close to traffic, no donor car or a car that still won't start after three tries are all good reasons to call for help.

How Pit Stop handles a jump start in Dallas

Pit Stop Roadside Services is open 24/7 at (214) 367-5302, and a technician typically arrives in 30–45 minutes in Dallas. The dispatcher gives you the price before anyone drives out, and that quoted price is what you pay for the job you described. Jump starts cover passenger cars, SUVs, pickups, light-duty work trucks and vans.

After the jump, the technician can check the battery and charging system, so you know whether the battery is likely to leave you stuck again. If it is worn out, the technician can replace it with a new battery where the car is, once the dispatcher confirms the right battery for your car and when it can get there, and once you accept the price. If the jump starts the car, you pay the quoted price even if the alternator turns out to be the real problem. If the car can't be started, the $35 to $75 service fee replaces the quote and the rest is refunded. The dispatcher tells you the exact fee for your job before you pay. The technician explains what they found so you know what to tell a shop.