Car batteries lose power for many common reasons. Cold weather, short drives, or leaving the lights on can drain a battery faster than you might think. As batteries age, they also hold less charge. Knowing why this happens helps you decide if a jump-start will work or if it’s time for a battery check.

To jump-start your car, you need jumper cables and another car with a working battery. Park the cars close together, but make sure they don’t touch. Turn both cars off and set the parking brakes. Then, open the hoods and find the batteries and their terminals.

Put one red clamp on the positive terminal of the dead battery, and the other red clamp on the positive terminal of the good battery. Then, attach one black clamp to the negative terminal of the good battery. Clip the last black clamp to a clean, unpainted metal spot under the hood of the car with the dead battery. Start the working car and let it run for a few minutes, then try starting the car with the dead battery.

Jump-starting a car is usually safe if you do it right. Keep the clamps from touching each other once they’re connected, and watch out for moving engine parts. If the car still won’t start after a few tries, the battery might be too weak or there could be another electrical problem. After a successful jump, drive for about 20 minutes to help recharge the battery.