A dead car battery means you’re going nowhere until you either replace it or get it jump-started. Jumping a car battery doesn’t have to be a scary process. If you don’t know how, then you can call for roadside assistance, but you can also do it yourself. Here’s how to jump a car battery safely so you can be on your way as soon as possible.
How to Jump a Car Battery – Step by Step
Whenever you work on your car, you need to keep safety in mind. For jumping a car battery safely, this includes making sure that other vehicles are at a safe distance and that you’re in a spot that’s out of danger’s way. Even if you already know how to jump a car you should check your owner’s manual to be sure you’re following the manufacturer’s recommendations. If you have any doubts, call AAA Roadside Assistance for help with the process.
All you need are jumper cables. You should have these on-hand, tucked away for that inconvenient moment when your battery fails. They come in anywhere between 10 and 20 feet long with longer cables being easier to use. The extra length means less maneuvering to get the cables to reach from your car to the car providing the jump-start.
There are also jump starters, which are essentially the cables with a built-in battery pack so you don’t need another car to help with the process. These are a bit bulkier and shouldn’t be stored in a hot car.
Positioning the Vehicles
Ideally, you want both cars to face each other head-on about 18 inches apart. Depending on where the breakdown happens, this might not be possible. Do your best to get as close to head-on as possible without letting the vehicles touch. Err on the side of caution. Be careful of car doors if the positioning isn’t ideal. You don’t want to open the door and have the two cars accidentally touch.
Some batteries are located under the back seat or in the trunk; consult the owner’s manual if you have trouble finding it.
Once the cars are positioned, put both cars in park for an automatic transmission or neutral for a manual transmission. Set the parking brakes, turn off the ignition and remove the keys.
Attaching the Jumper Cables
This is the part about jumping a car battery safely that makes people nervous, but there is no need to worry. Start by opening the hoods of both cars and finding the battery terminals. Usually, the terminals on the battery are red or black and you will see a + (red) and – (black) sign on the top. Make sure you can clearly see these signs; if the terminals are dirty, use a rag or brush to knock off any dirt or debris.
Attach the red, positive cable clamp to the red, positive terminal of the dead battery. You want this connection to be secure so wiggle around the clamp to get a tight grip if it feels loose. Next, attach the opposite end of the red, positive cable to the working vehicle’s positive battery terminal.
Attach the black, negative clamp to the working car’s black, negative battery terminal but do not attach the negative clamp to the negative battery terminal of the dead battery. Instead, attach it to an unpainted metal part of the car like a bolt or the engine block. Dead batteries can produce hydrogen gas – if there’s a spark you want it away from the battery.
Starting the Car
Start the engine of the working car and let it run a minute or two before trying to start the dead car. If the car won’t turn over at first, wait a few more minutes and give it another try. Speeding up the idle for a minute or so can sometimes help.
If the car still doesn’t start, then you may need to call for roadside assistance. It could be a number of problems like battery corrosion, fuses or the starter. A professional can diagnose the problem and recommend a repair.
Disconnecting the Jumper Cables
There’s an order to disconnecting the cables, too. Remove the black, negative clamps and do not let them touch while the other cables are attached to the car. Next remove the red, positive clamps. Do not let the red and black cables touch. You can now close the hoods and stow your jumper cables. Once your car is running, take it to a local repair shop to have the battery fully charged and tested.
See, it’s easy to learn how to jump a car battery. With a set of jumper cables and the help of someone with a running car, you can do the job yourself in no time.
Do you have an interesting story about a time you needed a jump-start? Share it with us in the comments below.
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8 Thoughts on “How to Jump a Car Battery Safely Every Time”
I leave my. Car in Florida parked for 9 months, what should I do about battery ?
Hi, thanks for your question. Here’s an answer from our Car Doctor John Paul: When storing a car for 9 months the battery is only part of the equation.
Disconnect the battery or better yet maintain the battery with a float stye battery charger (Battery Tender is one brand). This will keep the battery charged without overcharging it. Cover the car with a car cover even if parked in a garage or carport. Use moisture absorbing dry packs to remove humidity (people will put them in closets and you can buy them at “dollar-stores”). Air up the tires to the maximum on the tire sidewall (the tires will lose a little air over time). Fill the gas tank and add fuel stabilizer (Sta-bil is one brand). Wash and wax the car and vacuum the interior. Take to small blocks of wood (1/2 inch thick) and place them under wiper blades so the summer heat doesn’t damage the blades. Change the oil and check all the fluid levels before putting the car away.
If the battery is worn out and will not hold a charge as opposed to just being discharged, the black jumper cable, (negative) will need to be attached to the unpainted metal of the vehicle in order to start. This is because the batter is dead because it is internally shorted. If your place the jumper cables on the battery terminal, the current will travel the path of least resistance and travel through the shorted battery rather than the starter motor.
I have a 2006 Miata which spends most but not all of the winter in the garage. I purchased a Weego jump start battery and have been able to use to jump start the car when the battery is low.
When I bought my first car my father made me jumper cables and I always keep them in my car. One day I was in my driveway and the mailman drove by in his truck, stopped, and asked if I had jumper cables because a neighbor was in need. He borrowed them and then returned them. You never know when you’ll need them.
Thanks I am printing this out.
great advice for diy’s
very useful article