In brief, the correct order is to connect the positive terminal of the dead battery to the positive of the donor battery, then connect the donor’s negative to a grounded metal surface on the car with the dead battery, start the donor vehicle, then the dead one, and finally remove the cables in reverse order. This sequence minimizes sparks and reduces the risk of damage.
Jump-starting a battery can restore power to a vehicle with a discharged battery, whether you’re using another car or a portable jump-starter. The following guide lays out the proper order, essential safety precautions, and practical tips to help you perform the procedure correctly and safely.
What you need
Before you begin, assemble the gear and prepare the vehicles. Having the right tools and following safety rules reduces risk for you and the cars involved.
- Jumper cables in good condition and long enough to reach between vehicles
- A donor vehicle with a healthy battery or a portable jump-starter/power pack
- Safety items such as eye protection and gloves
- Knowledge of each battery’s terminals (positive vs. negative) and how to access them
- A well-ventilated area and no open flames or sparks nearby
Note: If the battery is cracked, leaking, severely corroded, or the vehicle shows signs of damage, stop and call roadside assistance. Do not attempt a jump-start in those conditions.
Step-by-step jump-start procedure
Follow these steps in order. Attach the cables correctly, power up the donor, start the dead vehicle, and disconnect the cables safely in reverse order.
- Park the donor vehicle close enough for the cables to reach, but ensure the vehicles do not touch. Turn off both engines, remove keys, and engage parking brakes.
- Open the hoods and locate the positive (+) and negative (−) terminals on both batteries. If a terminal is corroded, gently clean it with a cloth or brush if safe to do so.
- Attach one end of the red (positive) jumper cable to the positive terminal of the dead battery.
- Attach the other end of the red (positive) jumper cable to the positive terminal of the donor battery.
- Attach one end of the black (negative) jumper cable to the negative terminal of the donor battery.
- Attach the other end of the black jumper cable to a solid, unpainted metal surface on the engine block or chassis of the car with the dead battery (far away from the battery itself to avoid sparks).
- Start the donor vehicle and let it run for a few minutes to transfer charge, then attempt to start the vehicle with the dead battery. If it doesn’t start right away, wait a few more minutes and try again, but do not crank for more than 5–10 seconds at a time.
If the dead vehicle starts, remove the cables in the reverse order: first the black clamp from the dead car, then the black clamp from the donor car, then the red clamp from the donor car, and finally the red clamp from the dead car. Keep the jumped car running for at least 20 minutes or drive to recharge the battery fully.
Safety considerations
Jump-starting involves high electrical current, so safety matters. Use these guidelines to protect yourself and the vehicles:
- Wear eye protection and gloves; remove loose jewelry and avoid wearing metallic accessories.
- Keep the cables clear of moving parts and hot surfaces; never let clamps touch each other during the process.
- Do not attempt to jump-start a battery that is cracked, leaking, or frozen, or a vehicle with severe electrical or fire safety concerns.
- Perform the procedure in a well-ventilated area, away from open flames or sparks.
Common mistakes to avoid
Avoid misconnecting clamps, as reversing polarity or connecting to the wrong terminals can cause damage to the electrical system or battery.
Summary
In summary, the safe and effective jump-start sequence is: connect the red positive clamps to both batteries in the dead-to-donor path, connect the black negative clamp to a grounded metal surface on the car with the dead battery, start the donor vehicle, attempt to start the dead vehicle, and then remove the cables in the reverse order. Afterward, drive or idle the vehicle to recharge the battery and consider having the battery tested or replaced if it won’t hold a charge.