Every Guy Should Know How to Jump Start a Dead Battery

Winter weather can wreak havoc on your car in all kinds of ways, which is why it's important to prep by doing things like changing out your regular tires for snow tires, and making a de-icing solution you can spray on your windshield and doors. Another common car problem in the winter? Dead batteries. Millions of motorists are stranded by dead batteries in the U.S. each year. In fact, the American Automobile Association (AAA) alone responded to some seven million customers experiencing battery issues in 2024. While you may not be able to predict when your car battery might fail, you can prepare yourself for this event by learning how to jump start a dead battery and by having the necessary equipment to perform this road side repair. This simple skill, which requires a set of jumper cables and help from a second vehicle, will get your car up and running and you off the side of the road in minutes. We tapped Alan Gelfand, an auto mechanic with more than 30 years of experience and owner of Hollywood, Florida-based German Car Depot, to teach us how. 

Choosing Jumper Cables 

You’ll need a good set of jumper cables to jump start your car, which is why you should always carry a set in the trunk. Jumper cables should be 15 to 20 feet long, which is enough length to extend from one vehicle's battery to another without being so long that they reduce power transfer. The gauge, of the thickness of the cables, is also important. Gelfand recommends purchasing four-gauge jumper cables (the lower the gauge the thicker the cable). Thicker cables can better transfer power without overheating. “The use of inexpensive cables with thin wires leads to overheating and poor current delivery which results in more difficult jump starting operations,” he says. Also check the clamps on the jumper cables. “The (battery) terminals require solid well-insulated clamps which should grip the terminals tightly for proper function,” he says.

Using a Portable Jump Starter

While jumper cables can get you off the side of the road if you’re dealing with a dead battery, you still need a second vehicle to get your car started. A portable jump starter that you can keep in your trunk will start a dead battery without the need for a good samaritan. Portable jump starters connect similarly to jumper cables but instead of using a second car battery, they use a lithium-ion battery to provide enough power to start an engine. While these tools are handy, they also cost much more than a set of jumper cables, retailing for around $130. They also require maintenance, as you’ll need to recharge them every six months or so. You also shouldn’t keep a portable jump starter in your car in extreme heat as it can degrade the battery and even cause it to explode. 

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Can I Jump Start off an Electric Vehicle?

You should never use an electric vehicle to jump start your car. EVs also use a small 12-volt battery, but it typically doesn’t produce enough power surge to start an internal combustion engine. “Most electric vehicles are not designed to provide the kind of current needed to safely jump start another car, and doing so can damage the EV’s electrical system,” Gelfand says. 

Before You Jump Start Your Car

• Move the car out of traffic and into a safe area. 
• Position the second vehicle so that the two cars are either facing each other, nose to nose, or side side by side. The cars need to be close enough that the jumper cables can reach both vehicles’ batteries without the need to stretch the cables. 
• Engage the parking brake and open the hoods of both vehicles.
• Wear gloves and eye protection when jumpstarting a car. Keep a set of this PPE with your jumper cables in the trunk of your car. 

How to Jump Start a Dead Battery With Another Car

While jump starting a car isn’t complicated, Gelfand says incorrectly attaching the cables is one of the most common mistakes he sees and can be costly. “The process of reversing electrical polarity for any duration will cause harm to delicate electronic components while simultaneously triggering fuse blowouts and control module destruction,” he says. Follow this procedure for jump starting your car from a second vehicle:

• Locate the battery terminals on both vehicles and remove any plastic or rubber covers hiding the terminals.
• Attach one clamp to the positive (+) terminal on the dead battery, which is typically red. 
• Move to the second vehicle and attach the red clamp to the positive terminal of the good battery and the black clamp to the negative terminal of the good battery. 
• Finally, attach the second clamp to a clean metal part of the dead car’s engine block. Don’t attach this clamp to the negative terminal on the dead battery. Lead acid car batteries release hydrogen gas. Connecting a clamp to the negative terminal on the dead battery can cause a spark that could ignite gasses and cause the battery to explode.
• Start the engine on the car with the good battery and let it run for about five minutes. 
• Attempt to start the car with the dead battery. If it doesn’t work, wait a few minutes and try again. 
• Once the car starts, remove the cables in the reverse order that you connected them, beginning with the ground wire, then the negative cable on the donor battery, then the positive cable on the donor battery and finally the positive cable on the dead battery. 
• Allow the car with the drained battery to run for 20 minutes to recharge the battery. The battery might be bad and may not be able to hold a charge, so don’t turn off the car until you reach your destination. 

How to Jump Start a Car with a Portable Jump Starter

Starting your car using a portable jump starter is very similar to starting it with a second vehicle. 

• Attach the jump starter’s red positive (+) cable to the positive (+) terminal on the battery and the black cable to an unpainted metal surface on the engine bay. 
• Turn on the jump starter per the manufacturer’s instructions. 
• Start the car then disconnect the jump starter beginning with the black cable. 

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What to Do if Your Battery Continues To Die

If your battery continues to die even after your jump start the car and give it ample time to recharge, then there are likely other problems:

• Old battery: Car batteries typically last three to five years before you need to replace them. You can check the battery charge using a multimeter or take it to an auto parts store, where they can check the battery for free.
  
• Bad alternator: An alternator is responsible for charging the battery when the car is running. “A weak alternator provides enough power to start the vehicle but it does not generate enough charge to sustain battery life,” Gelfand says. An auto mechanic can check the alternator to see if it’s functioning properly.
  
• Parasitic electrical draws: This occurs when components in the car continue to draw from the battery even when the car is off. “Parasitic electrical draws are another common cause, where something in the car is staying on when it shouldn’t,” Gelfand says. If the battery and alternator are working properly, a parasitic draw is likely the culprit. Identifying a parasitic draw is a challenging, time consuming process best performed by a professional auto mechanic.