Last Updated on October 28, 2007
Please wear glasses in the unlikely event of a car or deep cycle battery explosion and save your eyes.
If done incorrectly, jumping a dead battery can be dangerous and financially risky. These procedures are ONLY for vehicles are that are both negatively grounded and the electrical system voltages are the SAME. These procedures would also apply to using emergency jump starters. DO NOT jump a frozen battery and ALWAYS connect POSITIVE to POSITIVE and NEGATIVE (-) to the ENGINE BLOCK or FRAME away from the dead starting battery. Reverse this rule to disconnect. The American Automobile Association (AAA) estimates that of the 275 million vehicles that will traveling in the U.S. during the Summer of 2003, 7.4 million (or 2.7%) will break down. Of that number, 1.3 million (or 17.7%) will require a battery jump to start their engine. The German automobile association (ADAC) estimates that their battery related service calls has increased from 21.7% per year in 1999 to 29.9% in 2004.
In cold weather, good quality jumper cables (or booster cables) with at least eight-gauge wire are necessary to provide enough current to the disabled vehicle to start the engine. Larger diameter, smaller gauge number wire is better because there is less voltage loss. Please check the owner's manual for BOTH vehicles or jump starter BEFORE attempting to jump-start. Follow the manufacturers' procedures, for example, some vehicles should not be running during a jump-start of a disabled one. However, starting the disabled vehicle with the good vehicle running can prevent having both vehicles disabled and provides a higher voltage to the starting motor of the disabled vehicle. Avoid the booster cable clamps touching each other or the POSITIVE clamp touching anything but the POSITIVE (+) post of the battery, because momentarily touching the block or frame can short the battery and cause extensive and costly damage.
6.1. If below freezing, insure that the electrolyte is NOT frozen in the dead battery. If frozen, do NOT jump or boost the battery if the case is cracked or until the battery has been full thawed out, recharged, tested. When the electrolyte freezes, it expands which can damage the plates or plate separators, which can cause the plates to warp and short out. When the battery is frozen, the best solution is to substitute a fully charged battery for frozen one or tow the vehicle to a heated garage. With any completely dead battery, cell reversal can occur. Please Section 14.14. The electrolyte in a dead battery will freeze at approximately 20°F (-6.7°C). The freezing point of a battery is determined by the SoC and the higher it is, the lower the freezing temperature. Please see the Electrolyte Freeze Points Table in Section 4.4.1. If the battery has been sitting for several weeks and frozen, then the battery has probably sulfated as well. Please see Sections 16 and 13 for more information. If the battery has been sitting for hours or a few days then the problem is either an excessive parasitic load like leaving the headlights on or a faulty charging system. Please see Sections 10 or 9, respectively.
6.2. Without the vehicles touching, turn off all accessories, heaters and lights on both vehicles, especially electronic appliances, such as a radio or audio system and insure there is plenty of battery ventilation.
6.3. Start the vehicle with the good battery and let it run for at least two or three minutes at medium RPM to recharge it. Check the POSITIVE (+) and NEGATIVE (-) terminal markings on both batteries before proceeding.
JUMP STARTING
[Source: BCI]
6.4. Connect the POSITIVE booster cable (or jump starter) clamp (usually RED) to the POSITIVE (+) terminal post on the dead battery [Step 1 in the diagram above]. Connect the POSITIVE clamp on the other end of the booster cable to the POSITIVE (+) terminal post on the good starting battery [Step 2]. If the POSITIVE (+) battery terminal post is not accessible, the POSITIVE connection on the starter motor solenoid from the POSITIVE (+) terminal post of the battery could be used.
6.5. Connect the NEGATIVE booster cable clamp (usually BLACK) to the NEGATIVE (-) terminal on the good battery [Step 3]. Connect the NEGATIVE booster cable (or jump starter) clamp on the other end of the jumper cable to a clean, unpainted area on the engine block or frame on the disabled vehicle [Step 4] and at least 10 to 12 inches (25 to 30 cm) away from the battery. This arrangement is used because some sparking will occur and you want to keep sparks as far away from the battery as practical in order to prevent a battery explosion.
6.6. If using jumper cables, let the good vehicle continue to run at medium RPM for five minutes or more to allow the dead battery to receive some recharge, to warm its electrolyte, and reduce the load of the dead battery. If there is a bad cable connection, do not wiggle the cable clamps connected to the battery terminals because sparks will occur and a battery explosion might occur. To check connections, first disconnect the NEGATIVE clamp from the engine block or frame, check the other connections, and then reconnect the engine block or frame connection last.
6.7. If using jumper cables, some vehicle manufacturers recommend that you turn off the engine of the good vehicle to protect it's charging system prior to starting the disabled vehicle. Check the owner's manual; otherwise, leave the engine running so you can avoid being stranded should you not be able to restart the good vehicle and increase the voltage to the disabled vehicle's starter motor.
6.8. If using jumper cables, start the disabled vehicle and allow it to run at high idle. If the vehicle does not start the first time, recheck the connections, wait a few minutes, and try again.
6.9. Disconnect the jumper or jump starter cables in the REVERSE order, starting with the NEGATIVE clamp on the engine block or frame of the disabled vehicle to minimize the possibility of an explosion. Allow the engine on the disabled car to run until the engine come to full operating temperature before driving and continue to run until you reach your final destination, because stopping the engine might require another jump start. Also, keep all unnecessary electrical accessories off to relieve the load on the charging system and allow it to add charge to the battery.
6.10. As soon as possible and at room temperature, fully recharge the dead battery with an external "smart" or "automatic" battery charger matched to the battery type, remove the surface charge and load test the battery and charging system to determine if any latent or permanent damage has occurred as a result of the deep discharge. This is especially important if you had a frozen battery or jump started a sealed wet Maintenance Free (Ca/Ca) battery. A vehicle's charging system is not designed to recharge a dead battery and could overheat and be damaged (bad diodes or burned stator) doing so or the battery could be undercharged and loose capacity.
In the event that the jumper or jump starter cables were REVERSED and there is no power to all or part of the vehicle, test the fusible links, fuses, circuit breakers, battery, charging system and emissions computer and, if bad, reset or replace. Their locations and values should be shown in the vehicle's Owner's Manual. If replacing the faulty parts do not repair the electrical system, having it repaired by a good auto electric repair shop is highly recommended.