If you have a flat car battery and do not have access to a car battery charger, this guide will demonstrate how to jump start a car with jumper cables. I would also recommend taking a look at our Car Battery Overview page for general information.
There are 3 main ways how to jump a car which are manually jump starting, jump starting with jumper cables and jump starting with a power pack or jump box.
If Jump starting a car with jumper cables, you will, of course, need a set of jumper cables. They can be known by other names such as jump leads, so don’t let it confuse you.
If you need to buy a set of jumper cables, they are not very expensive and can be bought quite cheaply on Amazon or Ebay. Jumper cables are so commonly used that you may even find them for sale at gas stations but will probably be more expensive.
Once you have a set of jumper cables, you will need a donor car with a good battery.
When jump starting a car with jumper cables, you will be connecting the flat battery from your car to the fresh battery in the donor car. You will effectively be stealing some of the charge to boost the flat car battery.
Below is what will be covered in this article.
How Long Does It Take To Jump Start A Car with Jumper Cables?
Some preparation will be required before you can begin to jump start a car. Once the preparations have been made, you will attempt the jump start, and finally, you will need to make sure that your car battery has been charged enough to start by itself the next time it is required.
So roughly how long does it take to jump start a car?
Using this method, and if everything goes to plan, you should have your car ready to go within the next 10-15 minutes.
Once you have prepared your car and the donor car, the initial jump start may only take a few minutes, but once you have managed to jump start your car effectively, the process is not quite over.
You will need to run your car to make sure that your battery retains enough charge so that it will start again without needing to carry out a further jump start.
How To Position Your Car To Attach Jumper Cables
To jump start a car with jumper cables, you will need to know how to best position your car so that the jumper cables will attach easily.
First you will need to position the donor vehicle close enough to your car so that the jumper cables will reach. You will need to open the hood of both cars and locate each car’s battery.
If you are on the main road, make sure you position both cars safely.
Turn off everything in your car that may drain energy away from the weak or flat battery. Electricals such as lights, windshield wipers, and the radio will drain the power that you are trying to replace.
Car Battery Safety
Before connecting your jumper cables, there are a few safety points that you should take into account.
It is important to note that when connecting jump cables, you should keep the ends from touching. When jumper cables are connected to a healthy battery, should you bring the opposite ends close together or touch them together, you will see sparking.
Many people think that the voltage passed from a car battery will not be enough to do serious harm, and although this is true in most cases, car batteries carry more than just volts.
Most car batteries are either 12 volt or 24 volts, and this voltagenwould not usually be enough to hurt somebody seriously, but it is not volts that you need to worry about.
Amps are much more dangerous, and a fully charged car battery can carry hundreds of amps through a single spark. This amperage can pack a punch and cause serious harm to a person.
Car batteries can also give off a gas called hydrogen while they are charging, and this can be highly explosive when mixed with air.
During charging, a small amount of this gas can be present near to the battery, and a spark could ignite this gas, causing the battery to explode.
Although very unlikely, the possibility is there, and an explosion like this can cause dangerous pieces of battery to become airborne, harming anyone nearby. Car batteries also contain sulphuric acid, which, if exposed to the skin, can react and cause severe burns.
Once the charging process is underway, it would be advisable not to stand right alongside the battery.
How To Jump Start A Car With Jumper Cables
Above, we have covered some of the safety aspects that you need to consider if you are going to jump start a car with jumper cables. You should not skip past these steps as safety should be of paramount improtance.
I have known many people that have wrongly connected both jumper cables and portable jump starters with no negative outcomes.
In my experience, the likelyhood of damage or harm is rare but you should always remain cautious.
However unlikely, there is a risk of severe damage such as your car battery exploding, fires or severe electrical shock. There is also a real risk of damaging the electrical system in your car.
Now that you understand the risks and have prepared your car we can look at how to jump start a car with jumper cables.
How To Tell Positive And Negative On A Car Battery
Before you can connect your jumper cables, you will first need to know how to tell positive and negative on a car battery.
Your jumper cables will need to be connected to the correct terminals and in the right order to avoid the risk of damage to the battery and to avoid the risk of such things as electrical shock or fire.
It is usually quite easy to determine which battery terminal is positive as it will be colored red while the negative terminal will be colored black.
If neither terminal is colored, there will be a (+) Positive and a (-) Negative symbol printed into the battery. You will find these symbols next to the corresponding terminal like in the image above.
How To Connect Jumper Cables
The next step is to understand how to connect jumper cables between the two batteries. The most obvious thought is that you connect both positives and both negatives on each battery, but it is not quite this simple.
It is important to understand which terminal to connect first and exacly where the cables should connect, soas to avoid harm to yourself and damage to the battery.
Firstly, make sure all battery terminals have any rubber or plastic covers removed. The bare metal terminal needs to be exposed. All covers should lift off easily.
Connect the red, positive jumper cable to the red positive terminal on the flat battery first. To connect the cable, clip one end of it on to the metal terminal with the crocodile type clip located at each end of the jumper cable. Check figure 1 on the diagram below.
You can now connect the other end of the positive jumper cable to the positive terminal of the healthy donor battery (figure 2).
Now connect the black, negative jumper cable to the black, negative terminal on the healthy donor battery (figure 3).
Finally, clip the other end of the black, negative jumper cable to an area of exposed metal on the car containing the flat battery, such as an unpainted bolt (figure 4).
You should not connect the negative jumper cable to the negative battery terminal on the flat battery, as this is not best practice.
The Jump Start Method
Now that the jumper cables are correctly connected, you will need to start the donor car engine. Running the donor car’s engine will help keep its battery charged while it passes some of its energy to the flat battery. It will also help if you keep the donor car engine at around 2000rpm or more.
After a minute or two, try and start the car with the flat battery. If it does not start, you should at least notice some signs of life.
Be patient, and do not make repeated attempts in short succession as this will continue to deplete your battery. After a few more minutes, try to start your engine again. Each time you do this, you should notice more and more life returning to the flat battery until there is enough energy to start your car.
How Long To Run A Car After Jump Start
Once you have managed to get your car started, you will need it to run for a short while. You will need your battery to recover sufficiently to retain enough charge for the next time you want to start your car.
The starter motor of your car requires a minimum of around 50-100 amps for it to be able to crank the engine, so how long to run a car after jump starting it?
Running your car for about 10 to 15 minutes should be long enough to place enough charge into your battery, although a full recharge would take around 5 hours.
Each time you drive your car, a cumulative charge will be added to the battery until it eventually becomes fully charged, but this should not be a method that you rely on as it will place undue strain on the alternator of your car.
The alternator is designed only to create enough charge to top the battery up. If your alternator is continually working at full power, it will burn out and will need replacing well before its due.
The best method to charge a dead car battery would be using a car battery charger. You would need to remove the battery overnight while the charger will charge your battery to full capacity.
Our How To Change A Car Battery guide and our How To Charge A Car Battery At Home guide can help.