Jump Starting An Engine

Jump starting an engine is a very common procedure, which for most cars is safe, but some cars cannot handle the power surges involved. If in doubt, check your owner's manual. Jumper cables are used to transfer power from a good (booster) battery to a discharged battery. The key to safe and effective jump starting is the correct hookup of the jumper cables. The operation is common enough - and relatively safe, provided proper precautions are taken. First, turn off your ignition to avoid draining any power that may be left in the battery. Park a vehicle that has a fully charged battery of the same voltage near the disabled car so that the two cars do not touch. The jumper cables to be used should not have to reach across either engine, where they might drop accidentally into the fans. Using old gloves or a rag, remove the cell caps from both batteries. Cover the holes with clean rags to contain any splashing acid. Another reason for doing this is that a chemical reactions inside a battery may produce hydrogen gas. Removing the caps allows the gas to escape. CAUTION: In extremely cold weather, look into the cells to be sure the battery fluid is not frozen. If it is, pockets of hydrogen gas may have formed and the gas could explode when the jumper cable is attached. Thaw out the battery before using the jumper. Attach the ends of one jumper cable to the positive posts of both batteries. Next, attach one end of the second cable to the post of the charged battery. Ground the other end by clipping it to a clean, unpainted part of the disabled car's engine, car frame, or other clean metallic part. Be sure all four cable clips are so positioned that they cannot accidentally contact each other or drop onto moving parts once the engine turns over and begins to run. CAUTION: Be sure to attach the second cable as directed, not to the ground post of the discharged battery. This is because a few sparks occur when this final connection is broken after the car starts. If the connection is made on the battery itself, the sparks could ignite any hydrogen gas that has accumulated. Allow the discharged battery to charge up for a few minutes. It can be determined if current is flowing by removing the ground cable temporarily, sparks indicate current. SPARKS CAN IGNITE BATTERY FUMES. DO NOT MAKE SPARKS NEAR THE BATTERY. With the assisting vehicle's engine running, and all the accessories in both cars turned off, start the disabled car's engine. Remove the negative (ground) cable from the problem car's engine and then from the post on the booster battery. Disconnect the first cable from the positive posts of the two batteries. Remove the rags from the vent caps on both batteries and dispose of them. Replace the vent caps.