How to Jump a Car:
Simple Steps to Bring Your Car Battery Back to Life
Trouble happens. You left your lights on and now you’re stuck. Luckily, you are a well-prepared motorist and keep emergency equipment in your trunk—including jumper cables. You are ready to bring your car battery back to life. Unfortunately, you are staring at the strange alligator-mouth clips wondering how these odd creations are going to raise your battery from the dead. Although you learn basic car maintenance in drivers ed, jump starting a car is not something everyone learns how to do. Having the right emergency equipment is a great start. You also have to know how to use it. So, here is what you need to know about how to jump a car. A few simple steps and you are on your way—wherever you were going.
What do you need to jump a car?
Before you can recharge and get going, you need a few basics:
- Jumper cables
- Power source – either a portable jump battery (a jump box) or another vehicle
Jumper cables are long, thickly insulated cables with toothy clips on one or both ends. These clips are called alligator clips (because they look like alligator heads). The clips are distinguished by color, usually red and black, to indicate positive and negative polarity. The red clip is positive. The black clip is negative.
Jump boxes—portable batteries used to jump start a vehicle without connecting to another vehicle—come with special jump cables. These cables connect the jump battery directly to the dead car battery. Road side assistance usually uses a jump box when helping stalled vehicles.
What you need to know about car batteries to jump start a car
Car batteries have two larger nubs, called terminals. There is a positive terminal and a negative terminal. Each should be clearly marked. Connecting cables to the right terminal is important to completing the circuit and gives power to the dead battery.
- Positive terminal – The positive terminal is usually the bigger of the two terminals. It is marked with “POS” or “+”. It will connect to the positive clip on the jumper cable, which is usually red.
- Negative terminal – The negative terminal on the battery is usually marked with “NEG” or “-“. This will attach to the other clip, which is usually black.
CAUTIONS WHEN JUMP STARTING A CAR:
- READ THE OWNER’S MANUAL. Some cars are not recommended for jump starting because they have sensitive circuitry
- DO NOT JUMP corroded, cracked, leaking, or visibly damaged batteries
- DO NOT JUMP frozen batteries
- DO NOT JUMP dry batteries
- DO NOT TOUCH CLIPS together. This is true when connected, but get in the habit by never touching the cilps together.
How to Jump a Car
Jump starting a car is commonly done from another car, although it can be done from a jump battery. You will be connecting the two cars’ batteries with the jumper cables. Make sure cars are in the right distance to have the jumper cables reach each battery. Pull the cars so that they are either nose-to-nose aligned or side-by-side.
Protect the donor battery
To ensure that the car donating a charge (the donor car) is protected, take these precautions:
- Match the kind of voltage system of the donor battery to the dead battery to be jumped. For example, a 6V and a 12V should not be used together.
- Connect alligator clips in the right order.
- Make sure the donor battery is not low.
The order of the connection (red to dead, red to donor, black to dead, black to metal) reduces the chance of shorting the good battery.
A quick test that there is enough voltage for the donor, be sure that the car giving he jump start’s headlights are steady and bright when the car is started. If the headlights dim, that can signal that the battery is low.
How to use jumper cables to jump start a car from another vehicle:
- CHECK BATTERIES: Make sure that the battery giving the jump has enough voltage and is a matching voltage system type (12V, 6V, etc).
- READY CARS: Put both cars in park or neutral, turn the ignitions off, and put on the parking brake.
- OPEN THE HOOD of each car.
- ATTACH ALLIGATOR CLIPS to the terminals in the following order:
- Red to Dead – Connect red, or positive, clip to the positive terminal on the battery of the dead car.
- Red to Donor – Connect the red, positive, clip to the positive terminal on the donor battery on the other car.
- Black to Donor – Connect the black clip to the negative terminal of the donor car.
- Black to Metal – Connect the black clip to an unpainted metal part of the dead car that is not directly next to the battery. One of the metal struts that hold the hood open is a good place to clip the second black, or negative, clip.
- START THE DONOR CAR so that the battery can supply power to the dead battery.
- IDLE the donor car, allowing it to run for a few minutes.
- TEST the interior light of the car being jump started. If it goes on, there may be enough power.
- START the dead car.
After the car is jump started:
- Unclip the clips in the reverse order you connected them:
- The black clip on the unpainted metal
- The black clip from the negative terminal
- Red clip from the donor car
- Red clip from the dead car’s battery
- Allow the car to run without stopping for at minimum 10-20 minutes.
What if the car doesn’t start after the jump start?
If the dead car doesn’t start after a few minutes of being powered then:
- Check the connections and repeat letting the car giving the jump run.
- Try starting the car again.
- If the car does not start after several attempts, the battery may be too far gone to be jump started.
Emergency Equipment to Keep in Your Trunk
- Bottled water
- Cable ties
- Emergency blanket
- Freezer bag of cat litter for oil or fluid spills (especially after a crash)
- Jumper cables or jump box
- Meal supplement bars
- Rain poncho
- Reflector roadside hazard triangle
- Screwdriver set
- Solar charger for your cellular phone for emergency calls
- Tire pressure gauge
- Tire jack and spare tire
- Wet wipes for cleaning up messes or staying fresh
For more safe driving tips and defensive driving information, visit idrivesafely.com
*This article was updated on 6/3/2020