If you have the right tools, jump-starting a car is an easy, three-minute process that can save you a tremendous amount of money. We’ve put together a step-by-step guide that will get you started — literally and figuratively.
Causes of dead batteries
It’s rare for a car that’s driven regularly to have a dead battery; it’s more common when cars sit for long periods of time. But older batteries have a harder time holding a charge, meaning they can go flat unexpectedly. Leaving the engine off with power-consuming accessories (like the radio) on can also drain the battery in record time.
Step 1: Get a set of jumper cables
Make sure to carry a set of jumper cables in your car at all times, just in case you end up needing them. Any set will do the job, but we suggest looking for cables gauge 4 to 6 in size, with a length of 10 to 20 feet. Cables of that size should be durable enough to work reliably, and a relatively long length gives you an added degree of flexibility in case you can’t park another car right next to the one being jumped. You don’t want cables that are too long, though, as the extra distance electricity has to travel may decrease the strength of the charge.
Portable jump-starters work, too, but the batteries that power them must be kept charged in order for them to work.
Step 2: Find a power source
You’ll need to park the running vehicle close enough to the one being jumped for the cables to reach from battery to battery, so identify where the battery is located in each vehicle. Batteries are usually mounted in the engine compartment, toward the front, but that isn’t always the case. They may be hidden under plastic covers, which need to be removed before jumping, located in the trunk or beneath the rear seat. Familiarizing yourself with all of this beforehand will help save time when you actually need to jump a car.
Step 3: Connect the jumper cables
Once the running vehicle is maneuvered into position, shut it off and open both hoods.
When handling jumper cables, make sure to keep the red (positive) and black (negative) clamps from touching each other. Once electricity starts flowing through the cables, this will create sparks and could lead to a short circuit in one or both of the vehicles. Having one person at each end of the cables can make the whole process easier.
The clamps connect to battery terminals, which are exposed metal nodes with wires connected to them. Before connecting the cables, make sure to brush away any dirt or grime to ensure a good connection. Confirm which terminal is positive (+) and which one is negative (–). You’ll normally find each symbol on the battery itself, next to the terminal. Sometimes the positive is under a red cover. Ask for help when in doubt; it will save you a potentially costly repair bill.
Found them? Good. Connect one of the red clamps to the positive terminal of the dead battery. Then, connect the other red clamp to the positive terminal of the live battery. Next, connect a black clamp to the negative terminal of the live battery. Instead of connecting the second black to the negative terminal on the dead battery, find an unpainted metal surface on the vehicle and connect it to that instead. This will make jumping safer.
Step 4: Fire it up
Start the car with the good battery, then try to start the dead car. If it refuses to start, its battery may be too far gone to take a jump, or it might need more time to charge. Let the running car idle for a minute or two and try again. But, if the engine spins without firing, you may have other problems unrelated to your battery.
If the car fires up, leave it running while you disconnect the cables. Making sure not to let the clamps touch while any part of the cable is still attached to a battery; disconnect them in the reverse order you attached them in, starting with the black clamp clipped to the car being jumped, and ending with the red clamp on the positive terminal.
Once the cables are disconnected, keep your car running and drive it for at least 15 minutes to give the alternator enough time to charge the battery. Keep the jumper cables handy in case you end up needing them again, too. If you have to ask for a jump every day, and if you know your battery is good, you likely have an alternator problem.
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