How to Jump Start a Dead Battery

close-up of jumper cables on a car battery

Get Your Car Running Again

Other than a flat tire, what is the worst way to get your day off to a bad start than a dead car battery? You must hope you can find somebody to give you a jumpstart and hope you’re not parked where it is impossible for them to reach your battery! Or you hopefully belong to an auto club that offers jump start services. But no matter the kind of help you have, all of this can make you late for school, work, or other appointments. 

If you don’t have a jump start service to call, if you can find a fellow driver with jumper cables that is willing to help you can provide your own jump start service. Before you do this, make sure you know the proper process, or you can do severe damage to your car and/or theirs. 

How do you jump start a car?

This skill isn’t learned as much as filling the gas tank, but it can be a critical skill and remembering it could keep you, or somebody else, from being stranded: 

  • Park: Both cars should be as close to each other as possible, without touching, and the engine should be turned off. 
  • Preparation: Open the hood on both vehicles, then unwind and untangle the jumper cables.
  • Connection: Hook the red clamp of the jumper cable to the dead battery’s positive terminal, indicated by a + emblem.  Then, hook the red clamp to the positive terminal, indicated by the + emblem of the working battery. Hook the black clamp of the jumper cable to the working battery’s negative terminal, indicated by a – emblem. Then hook the last black clamp to an unpainted metal surface on the dead car.
  • Starting the cars: In this order, start the car with the working battery, wait a minute then start the car with the dead battery. 
  • Disconnect: Now, in the reverse order that you hooked the two cars together with the jumper cables, remove the cables, assuming the dead car battery started.
  • Let the Car Run: Let the car engine rev up a few minutes, and then drive it for 15 minutes or more to get the battery charged. 

If the dead battery car won’t start, check the jumper cables connections, and try again. If it still won’t charge, either the battery is completely dead or there is another issue that must be dealt with. 

So, why do the positive cables need to be connected first? This will avoid shorting the battery of either car and if either is a newer car with a computer, it will prevent damage to the computer and entire electrical system. 

Why does the last jumper cable end need to be attached to an unpainted metal part of the dead battery car? This will avoid any potential possibility of damaging the dead battery and the person(s) performing the jump start service. 

How long does it take to jump start a car?

Untangling and unwinding the jumper cables will take longer than the actual jumping off process if the dead battery will jump off. Once the cables are connected, the jumpstarting process will usually take approximately five minutes.

If you have a jump start service, they will likely have their jumper cables in a ready-to-use mode, i.e., not tangled up. You’ll need to show your membership card and driver’s license though, which may take longer than the jump-starting process. The jump start process will take about 5 minutes for them as well. 

Is a jump start bad for a car?

It can be, which is why you never want to try providing or receiving a jump start service if you or the other person isn’t sure of the proper process. A damaged battery can start a fire when the jumper cables are connected. A car battery contains sulfuric acid that becomes vapors that can be highly flammable. Because jumper cables can spark and ignite those vapors, it can start a fire, and in rare cases, they have exploded. 

Does jump starting a car damage the computer?

Absolutely!  Most vehicles on the road today have multiple computers that power vital functions, as well as the radio, navigation system, televisions, and other devices.  When jumper cables are incorrectly connected or crossed, the potential damage can cause an electrical short, damaging one or more of those computers. 

Will you know when that happens? Not always – it may be after you start the dead battery car and start driving, and then realize the radio isn’t working, the power locks and windows aren’t working, or you identify other isues. Proper jump start service is more important on cars today than ever before.

How long should a car run after being jump started?

A minimum run time of 15 minutes is recommended. The longer the better to allow the alternator time to recharge the battery. 

Why won’t my car jump start?

Your dead car battery could be due to the weather, or maybe you left the lights on. It could also be as simple as having an old battery that’s past its time. When a jump start service doesn’t get your car started, it could also be for any of the following reasons: 

  • The Battery: As we have mentioned, the car battery may be too old; typically they need replacing every three to five years. The battery may also be damaged beyond a jump start service.  A new battery is your only option in these cases. 
  • The Battery Terminals: The battery terminals could be corroded or loose, restricting the electrical flow to the car. Removing the battery cable ends and with a wire brush, clean the corrosion off, including the bolts that connect the cables. This will usually allow the jump start service to work if there isn’t anything more wrong with the battery. 
  • The Alternator: The car battery needs the alternator to meet all the electrical needs of a car. They are a team with the alternator recharging the battery’s electrical power.  The alternator also supplies the electrical current needed to all the car’s electrical accessories while you’re driving. Headlight dimming when you’re stopped is one indication that you need your car inspected by a mechanic. A jump start service may get your battery jumped and your car running again, but dimming lights mean the battery is about to be done. 
  • The Starter Motor: The starter on your car requires electricity from the battery to start the car. When the starter is defective, it can’t start the engine, which keeps the battery from providing electrical power to the car. Time to schedule an appointment with your mechanic. 
  • The Safety Switch: Automatic transmission cars have a safety switch that will keep the car from starting if it isn’t in PARK or NEUTRAL. A manual transmission car has the same switch that won’t allow the car to start if the clutch pedal isn’t fully depressed. If that safety switch is bad, a jump start service isn’t going to get your car started. The switch needs to be replaced and then you should be able to proceed with happy motoring. 
  • The Jumper Cables: The jumper cables must be properly connected for a successful jump start service of a battery that isn’t completely discharged. If the jumper-cables are too long or too lightweight, they may not have enough current to jump start a car. A key investment for your car is a quality pair of jumper cables.

What to do if your car dies and you don’t have jumper cables?

There are a few little-known tricks that may provide a jump start service when there aren’t jumper cables around or battery tricks you can try to get your vehicle running again. 

  • Tapping on the battery terminals; jarring them could provide a better connection for the battery.
  • Trying to start the car in neutral can sometimes establish an electrical contact inside the safety switch. 
  • Trick the computer by pressing the accelerator halfway then start the engine. You may need to try this a few times before the car starts. 

How much does jump start service cost?

This can vary from area to area and what type of car you have. The average cost is around $100 to $150. 

close-up of jumper cables being attached to a car battery

One Last Jump Start Service Question

If your motorcycle won’t start, do you know how to jump start a motorcycle? Is it different from jump starting a car? Well, if you have the time, simply connect the battery to a charger and wait for the battery to charge up. But, if time is of the essence, there isn’t any difference between a jump start service for a motorcycle and a car. 

A motorcycle can be jump started from a motorcycle or a car. The only difference is when a motorcycle is jump started by a car, the power of the car battery will immediately power up the bike’s battery. This means you shouldn’t need to leave the jumped bike running to get it going again.