Jumping a Discharged Battery
*MEDIUM*
On occasion, you may find it necessary to give a jump start or receive one. Great care must be taken so as not to damage the vehicles or cause personal injury. If you must jump start an engine with discharged battery, use the following procedure:
- Be certain the batteries of both vehicles have the same polarity (usually a negative ground) and the same voltage rating (usually 12 volts). If they do not, the jump start procedure cannot be used.
- Park the vehicle with the discharged battery on level ground with the engine OFF, the parking brake engaged, and the transmission in PARK (for automatic) or REVERSE (for manual). Raise the hood. Turn the heater fan motor on HIGH, but keep all other electrical accessories and lights OFF to prevent voltage surge from damaging them. See your owner's manual for possible additional directions.
- Inspect the weak (discharged) battery to be certain it can accept a jump start. Remove any corrosion if it is present. If the discharged battery's cells can be accessed and the weather is cold, confirm that the electrolyte inside is not frozen. Do not disconnect the discharged battery; that may harm the electrical system. If the discharged battery is cracked, leaks fluid, or has loose terminals, it should not be jumped. Instead, replace it. If the discharged battery has vent caps, remove the caps and cover the battery cells with a cloth. Do not smoke or bring any type of flame near the discharged battery.
- Place the vehicle with strong (booster) battery near discharged battery. The vehicles must not touch. Turn all electrical switches OFF, except keep the heater fan switch on HIGH. First attach one end of the red jumper cable to the positive terminal of the discharged battery, then the other end to the booster battery's positive terminal.
- Connect the black jumper cable to the booster battery's negative terminal.
Lastly, attach the remaining end of the jumper cable to the
engine block or frame of the
car with the discharged battery. Do not attach it directly to
discharged battery because any resultant sparks could cause an explosion.
Make the attachment on a ground connection as far away from the discharged
battery as possible.
- Start the booster battery's engine. Let it idle.
- Try to start the discharged battery's engine. Do not crank the engine more than 5 seconds at a time; long cranks can weaken a good battery. Wait about 30 seconds and try again. Once started, let it idle too. Racing either engine will not charge the weak or dead battery any faster. If the dead vehicle does not start after 3 or 4 attempts, the battery is not the problem.
- Disconnect the cables immediately after starting the second car, especially if one of the batteries is sealed (maintenance-free). Disconnect the cables in the exact reverse order in which they were connected. This means the negative cable on the engine or car frame of the discharged battery is disconnected first. The remaining end of the negative jumper cable is disconnected second. Next, the booster battery's red jumper cable is disconnected. Lastly, the discharged battery's red jumper cable is disconnected too.
