Because of the potentially severe hazards due to improper use of jumper cables it must be done correctly. Auto batteries contain Sulphuric Acid which can blind you, or at the very least burn your skin. Also auto batteries vent off Hydrogen Gas which is highly explosive even from the slightest spark. Because of this danger it is critical to attach the jumper cables in a precise sequence.
1. Park the vehicle with the GOOD battery close to the vehicle with the BAD battery but do not let the vehicle touch each other. Make sure the cables are not routed so as to touch any moving parts, such as a fan blade.
2. Attach the jumper cable Positive + terminal to the GOOD battery Positive + terminal.
3. Attach the other end of the jumper cable Positive + terminal to the BAD battery Positive + terminal.
4. Attach the Negative - jumper cable terminal to the GOOD battery Negative - terminal.
5. Attach the last jumper cable Negative - terminal to a heavy metal ground part of the engine and NOT to the dead battery Negative - terminal. Reason being this last connection will cause a spark, and you do not want a spark next to the battery where it could ignite the Hydrogen.
6. If the engine of the donor vehicle with the good battery was not left running, start the engine and let it run for 2-3 minutes to put a charge in the bad battery.
7. Start the vehicle with the BAD battery and then remove the jumper cables from the batteries in the exact opposite order you installed them.
