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The Proper Way To Boost A Dead Or Low Car Battery


Possible Causes

There are several things that can cause your battery to die on you and most of them have nothing to do with anything you did or didn't do.

Bad Battery

Bad Connection

Bad Generator


Interior Light(s) or Headlights Left On

Oh No! My Battery Is Dead!

Just about everyone who is driving has experienced a dead car battery. No matter who you are it happens. And when it happens you get a sinking feeling.

Anyone who is not familiar with the mechanics of a car might get a little concerned but there is nothing to be concerned about.

The first thought that usually comes to mind is: What could have caused my battery to go dead? Then usually that thought is replaced by: How am I going to get this car started?

Well both of those thoughts is what this article is about.


Just in case you ever have a dead battery you should keep a set of jumper cables in the car trunk. Having them is not an omen of bad things to come but it is a good precautionary measure to have them just in case of a problem.

In the case you ever do find yourself somewhere with a dead battery you will have the necessary equipment to be able to simply ask someone nearby if you could use their car battery to boost yours without having to find some cables first.

Most people will be glad to accommodate you in that instance. After all you don't want to wear out your welcome with a stranger by asking them for too much.

Battery Jumper-Booster Cable


Battery Boost Diagram


Battery Boosting Process


A secure, tight connection is necessary to properly boost a dead battery.

A simple formula to remember as to how to connect the cables is: Positive On-Negative Off. In other words when attaching the cables you want to attach the positive (red) cables first to the live battery and the dead battery. Then attach the negative (black) cables to the live and dead batteries. And when removing them take the negative (black) cables off first followed by the positive (red) cables.

Once you have the hoods on both cars open and the cars close enough for the cables to reach each battery you are ready to go. Try to make sure the batteries are as close to each other as you can get them. The engine of the car giving the boost should be running.

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Start by clamping the red cable to the live car battery's positive post (the little nub sticking up from the battery). The post should have an (+) marking either on the post itself or on the battery in front of the post. After clamping the red cable on the live battery clamp the other end on the dead battery's positive post.

After you have attached the positive cables now attach the negative ones. First clamp the black (negative) cable on the live battery's negative battery post which should be marked by an (-). Then clamp the other end of the cable to either the dead battery's negative post or to a metal part of the engine frame. This is known as "grounding." If you have made a solid connection you should hear a distinct deceleration or reduction of RPM's (revolutions per minute) of the engine of the car that is doing the boosting.

Once you have a good connection start the engine of the car with the dead battery like you normally would. If the dead battery is not damaged or weak and you have a solid connection between the two batteries the car with the dead battery should start right up. If it does not wiggle the connections on the batteries to see if you can get a better connection and try starting the car again. If you are unsuccessful the dead battery may be too low to start from just a boost, you may still have a bad connection or the dead battery may be damaged and unable to be boosted or charged. If it is either of the last two reasons a tow truck will most likely be needed or, as I have done before, bringing a new battery to the car. If the car is in a safe location you may want to try replacing the battery at the location which is cheaper than a tow AND battery replacement.


Before attempting to boost your battery make sure that you are not standing in water if you can help it. Water is an electrical conductor and on rare occasions you can receive a small shock if water is present with electrical current just as you would not want an electrical appliance to fall into the bathtub with you.

Rubber soled shoes like tennis shoes will guard you against that possibility though.

Also make doubly sure that you attach the correct cable to the correct terminal. Crisscrossing the cables can result in a possible back charge that could cause an explosion of the battery. It's a low risk but one to be aware of.

Charging a dead battery is not as complicated or dangerous as you may have been led to believe as long as you know the right way to do it.

Auto Instrument Panel With Battery Indicator Light


Car Instrument Panel With Battery Voltage Gauge


On The Road Again

When you are back on the road driving again be sure to check your gauges and indicator lights on your dashboard to see if there is anything showing a charging problem. Ideally your charging gauge should be showing the needle leaning toward the right (charge) and your alternator/generator dash light should be off. If your gauge is showing a negative charge (left of center or below) or your battery indicator light is on (small battery-shaped light) you need to get to a mechanic shop to see what the problem is.

As a precaution you should go to a mechanic regularly to get the charging system checked anyway just to make sure everything is functioning properly.

Actually a dead battery can be a blessing in disguise because it can be warning you of a more serious problem down the road within your charging system.

Home Car Battery Charger


Automobile Charging System


How To Boost Your Dead Battery

Jump Starting Your Car


Mechanics Guy from NY on June 16, 2016:

Nice to know

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