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How To Jump Start a Car

So there you are, stuck in a parking lot with a car that does little or nothing when you turn the key. Assuming you've gone through the checklist of things to make sure of (see below), you're going to have to get a jump to get going again. This won't be too hard, since you carry cables in your trunk just in case. Right?

Before you break out those cables and hook up to a friendly passerby to get a jump, let's quickly go through the things you should have already done to be sure that a jump start is actually what you need.

Is the car not starting because the battery is dead? A dead battery could be the result of leaving lights on, having a short somewhere that's draining it, a bad battery, etc. To make sure the battery is actually drained beyond the point that it will start the car, check those connections and see if moving or jiggling or cleaning them will remedy the issue without a jump start.

Is the alternator broken? If your alternator is bad, then it's not charging the battery or providing power to the vehicle while it's running. In this case, the vehicle runs off the battery alone, usually not for long. If this is your issue, you'll know it because things like the headlights and other items will slowly dim as the battery drains. If you aren't sure, charge the battery from another vehicle enough to get started (see jump start instructions below) and then disconnect the cables and see if the vehicle continues charging the battery or eventually dies out again. You can probably charge your battery enough from another car after 10-15 minutes of hook-up to get a few blocks to a parts store for a more thorough test.

Is the starting circuit OK? If you turn the key and you hear the tell-tale "clicking" or the half-hearted attempt to turn the engine over before giving up, then your keyswitch is probably just fine. If you hear nothing, then you may have a defective keyswitch. Without being able to test it, though, you'll have to flag down someone and try a jump start regardless, because if you cannot start the car when it's got power, it's a good sign that it's not the battery that's the problem.

How To Jump Start Your Car

So now to the nitty-gritty. How do you properly jump start a car without causing accident or injury to yourself or the vehicles involved?

First, have the proper tools. You'll need a good set of jumper cables (do not use cheap ones, like this guy did). You should also have safety glasses or goggles and rubber gloves. These are safety items that you should keep with your cables in the car. You will also need an operational car with a power system similar to yours (most cars are 12V). Alternatively, you could have one of those jump systems that provides its own power without another car.

Park the operational car so that you can access both batteries with your cables. Usually if they are in adjacent parking stalls or nose-to-nose, your cables will likely reach. It's better not to have cables stretching over a running engine, but in some situations, this may not be helped so you'll need to figure out how to keep those cables from dragging on the engine or moving parts - loop them over hood props or around safe places.

Next, hook them up properly. Shut off the running car and turn the ignition switches on both vehicles to "off" - remove the key to be sure. Locate the positive (+) and negative (-) side of each battery so you'll know which is which.

Attach the red cable to the positive side of the good battery and the other end of that red (positive) cable to the + side of the dead battery. Next, attach the negative (black) cable to the good battery's negative side and the other end of the negative cable to a section of unpainted metal on the dead car. This is important as a negative terminal connection on a dead battery could result in the ignition of leaked battery acid and an explosion. You'll want the negative connection to be away from the battery, but it can be as small as a bolt head or anything the cable will reliably clip to.

Be sure you DO NOT "temporarily" connect a cable to something other than where it should be connected. This includes "insulated" things like the cables themselves as the teeth of the clamp could penetrate and complete a connection, destroying the electrical in your car and, worse, the good Samaritan's car that's stopped to help. Give a rubber glove to your Samaritan and have them hold the unused ends until you need them, if need be.

As quickly as possible, start the car with the good battery. You want to prevent too much battery drain as the now-connected batteries will attempt to equalize, sending power from the good battery to the dead one, charging it. This, of course, is your goal, but you don't want to kill the good battery doing it. Plus, a running car produces more power and will charge the dead battery faster.

Let the two vehicles sit, with the good one running, for about two or three minutes before you attempt to start the dead car. If your bad vehicle has a voltage meter, you can turn on the key (without starting) and watch to see how it's doing. Allowing the two or three minutes of charge time will give your battery enough juice to do most of the work starting your car on its own. It will also mean there's enough power to do all of the things a battery does before the engine becomes self-sufficient (is running).

If you suspect a bad alternator, now is the time to check that. Disconnect the cables carefully and see if the once-dead battery becomes dead again. If, after a few minutes, it has not, you're probably good to go. To be sure, you should see a shop to have the battery and charging system tested.

Disconnecting Battery Cables

There is no set procedure for this, but courtesy says that you should disconnect the Samaritan car first, since the chances of causing problems with accidental connections are more likely to happen after one car is disconnected. Remove both cables from the Samaritan car (start with the red cable first) and then remove them from yours.