How to jump start a car effectively | The Definitive Guide

Jump starting a car is one of the most fundamental things to know about vehicles but can also be a bit scary. If you need to jump start your car and you are a bit scared about it, you came to the right place. Here you’ll learn how easy is to boost your car’s battery and find alternative and safer methods to the traditional jumper cables.

There are 3 main ways to give your battery that boost it needs to start your car. Each method has its pros and cons and we’ll review each one to determine what is best.

And don’t worry, this is simpler than you think.

Why jump starting is necessary?

These days cars are complex systems full of electronics and gadgets to make your life easier. While this is great, the initial spark needs to come from somewhere and here is where jump starting a car becomes a need.

The battery of your car is that power source from where this initial spark comes. This is what starts the engine and it is essential to get the car moving every day. Once the car starts, the alternator recharges the battery and keeps all the electronics powered.

But when the battery fails or is discharged there is no way to get the car started, and this is when your vehicle needs a boost so it can start and then charge the battery.

It is a good idea to check the condition of the battery to see if it is still charging or not. You can have a professional do this to diagnose your battery and see if it needs replacement.

Three effective ways to boost a car battery

When jump starting a car always remember safety. There is a reason why people fear this process, since the currents and voltages involved can cause you severe injuries or death. A neglected procedure could make a battery explode and cause harm, so be sure to follow all the steps described here to a safe operation.

These are the 3 main ways to jump a car battery compared.

MethodJumper CablesJump StarterSpare Battery
Effective to jump start a car
Stand alone method
Can jump most cars
Easy to use
Protect battery’s health
How long to jump start15 – 30 minutes10 seconds – 3 minutesInstantly (when works)
Extra functionalities
Flashlight and USB charging ports
3 ways to jump start a car

With jumper cables (and another car)

Jumper Cables
Starting your car with Jumper Cables

This is the most common way to boost a car’s battery and bring it back to life. This method scares most people because sometimes there are some sparks.

You’ll need another car with a good battery and a set of jumper cables. This other car needs to have a similar or greater motor size to the one you want to jump. That is, if you want to jump a 4-cylinder using a 6 or 8 cylinder one, that’s OK, but the other way around may not work or will take a long time.

  1. Both cars should be turned off.
  2. Open the hood of both cars.
  3. On the dead battery car, connect the red clamp of any of the ends of the cables to the positive terminal of the battery.
  4. For now, place the black clamp away of any metal part and leave it there.
  5. Go to the car with a good battery and connect the red clamp of the other end of the cables to the positive terminal of the good battery.
  6. Connect the black clamp to the negative terminal of the good battery and go back to the other car.
  7. Now look for what people call “a ground”, which is nothing more that an unpainted metallic part and connect the black clamp to that.
    1. This ground place can be any screw or nut. Doing this will avoid most sparks. Just make sure you have good connections all over the place.
  8. Turn on the car with a good battery, and turn off the heater, radio and everything else to ensure all the possible power goes to the other battery.
  9. Give it a minute or two and try to start the other car.
    1. This waiting process can get a bit lengthy depending on the condition of the good battery and other factors. I have had to wait up to 30 minutes to jump start a car.
  10. Once you are able to turn on your car, it’s time to unplug the cables.
  11. Disconnect the black clamp from the ground you found at the car with the dead battery.
  12. Go to the other car and disconnect the black clamp from the negative terminal of the good battery and the red clamp from the positive terminal as well.
  13. Go back to the other car and disconnect the red end from the positive terminal of the battery.
  14. You are done.

Given nothing else is wrong with your car, the bad battery is now being charged by the alternator (we’ll talk about this later). If you can and are at a safe place, let the car on for about 15 minutes. If not, drive around for 15 minutes, but don’t go that far nor turn the engine off or your battery may need another jump.


  • Cheap
  • Effective to jump start a car
  • It also charges the battery


  • Need another car
  • This car must have similar motor size
  • Not very easy to do
  • May be dangerous
  • Can damage the battery of the other car
  • May take a few minutes

With a jump starter

Jump Starter
Boost your battery with a Jump Starter

This is another popular method to jump start a car. From all the methods here this is the safest and easiest by far, although a jump starter may cost you a bit more than a set of jumper cables, you won’t need any other car to jump your battery with one of these.

A jump starter is a portable device, sometimes in the form of a box and sometimes a bit bigger, that holds charge in an internal battery and is powerful enough to give that initial boost to your battery. More than often these are more than only jump starters and are full of protections to ensure you, your battery and your car are safe while jumping the battery.

Most jump starters come with its own instructions manual and you should have pretty clear directions there to follow, so make sure you read the manual and follow all the needed steps.

However, here is a step by step process for you to follow using one of these jump starters.

  1. Ensure the jumper box is turned off.
  2. Connect the jumper cables to the jump starter if needed.
  3. Connect the red clamp to the positive terminal and the black clamp to the negative terminal of the battery.
  4. Turn on the jumper box. Most units have an “On” button to start passing power to the battery.
    1. The unit may give you some error message, which could be related to a wrong connection or some sort of protection. You will need to refer to the manual for this.
    2. Some units do not detect a battery if this is heavily discharged, so you may need to activate the “boost” mode, if available in your jumper box.
    3. Some units, even when they advertise this boost mode as a “force power through” may still not recognize the battery if it is heavily discharged. If this happens, you may need to charge the battery before being able to jump start it.
  5. Give it a few seconds and try to jump start your car.


  • Don’t need another car
  • Portable
  • Effective to jump start a car
  • Very intuitive to do
  • Safe
  • It won’t damage the battery
  • Most times takes seconds to jump start a car
  • Most jumper boxes come with extra functionalities like flashlight and USB charging ports for small electronics


  • A bit expensive
  • Jump starter needs to meet certain specifications
  • Jump starter may not boost a heavily discharged battery
  • May take a few minutes

With a spare battery

Start your engine with a Spare Battery

This method is the hardest, most time consuming and most expensive one of all and may pose a risk for the electronics of your vehicle. Yet if you are in a situation where all you need is the car to start, it is still an effective way to jump start your battery.

It requires you to have a spare battery in good condition with you. This spare battery needs to meet specific conditions to make sure it can jump start your car.

Here the steps you need to follow.

  1. Disconnect both terminals from the battery of your car and remove it.
  2. Install the spare battery in your car and connect both terminals.
  3. Try to start your car.
  4. Once the car is started, and without turning it off, disconnect both terminals of the spare battery. You should be safe from sparks or anything, yet it would be a good idea to wear gloves for this.
    1. Your car should continue to run even if the battery is not present because the alternator is producing the current for it to run.
  5. Now place the old and discharged battery in your car and connect both terminals to it.
  6. The car will continue to run and the alternator will now charge the battery.


  • Don’t need another car
  • Effective to jump start a car
  • Most times takes seconds to jump start a car


  • A bit expensive
  • Need a spare and charged battery
  • Not completely Safe
  • Not very intuitive to do
  • May damage spare battery
  • Battery needs to meet certain specifications

Is jump starting a battery the same as charging it?

The short answer is no. In reality the jump start is given to the engine of the car and not to the battery. The battery is that jump starter your car brings with it all the time to help it get started.

Jump starting a car means to give the engine that initial spark to get it started. Once this happens, the alternator produces the current to keep it going and this charges the battery at the same time.

When to charge and when to jump start my car battery?

In some cases you may not be able to jump start a car because the method you use does not have enough power to do it. In such case, the battery may need to be charged.

A jump starter may not detect the battery if it is heavily discharged, yet some of these jumper boxes come with a boost mode that when activated forces power through the battery and gives the engine that initial spark it needs to start.

If the booster provides enough power to start the engine, the alternator will charge the battery.

On the other side, using jumper cables not only jump starts a car but also charges the battery because the cables connect it to a power source (the other battery) that charges it as well. This is why sometimes jumper cables may need a bit of time. What is truly happening is the battery is being charged, and the car will start when the battery is sufficiently charged.

When using a spare battery, this battery gives that boost to the engine and gets it started. Then, when you connect the discharged battery, this gets charged by the alternator.

What size jump starter do I need?

This depends on the motor size, the fuel type of your car and the temperature at which you intend to jump start a car.

Jump starting a V8 will be harder than a V4. A Gas vehicle will be easier than a Diesel truck since gasoline is lighter than diesel. And jump starting a car at ambient temperature (25 ℃ or 77℉) is much easier than doing it in a snowy day.

All this has to do with how heavy would be to move the engine to give it that initial boost. If you had a hand crank shaft, the strength required to start a car in each of these scenarios would be very different.

For the most part, with gasoline vehicles and at ambient temperature, you may need anything between 250 and 600 Amps to jump start a car.

For each Liter of size of the motor, you’ll need 61 Amps of current. This may vary with temperature and will be more if the temperature goes down.

Jump starters come rated in Amps, and the more Amps they can supply the bigger the motors and in the worst conditions they can jump start.

If you have a gasoline vehicle that is either 4 or 8 cylinders and you live in a place where temperatures are not that cold, then a 1000 Amps jumper box is good for you.

If all the conditions above for you are true but you live in a place where temperatures are colder, then something that can supply 2000 Amps or above is what you need.

How to jump start a diesel truck?

Diesel vehicles are harder to start than gasoline cars. This is because diesel is heavier than gas and diesel motors are heavier as well.

You could start a diesel truck with a 1000 Amps booster as well, depending on the motor size. You want to check your diesel motor size and start from there.

At ambient temperature a diesel car will require 122 Amps for each Liter of size of the motor. Use this ratio to assess the capacity in Amps you may need from a jump starter. This may be higher if temperature goes down.

Can jump starters charge batteries?

Jump starters do not charge batteries, they just provide the initial energy for the engine to start so that the alternator can charge the battery.

Some jump starters come rated as chargers as well. This way if the jumper does not detect the battery because it is heavily discharged you can still charge it to start the car.

Yet you have to make sure the booster you get comes rated as a charger as well. If not, then it won’t do it.

Conclusion: The best way to jump start a vehicle is using a battery booster

If you are still looking to find the best way to jump start your car then it has to be with a jumper box. This is not just the simplest, fastest and safest way to do it, but works for 95% of the times you need that initial spark to keep you on the road.

Jump starters as well are cost effective solutions for starting a car, are pretty portable and can hold its charge for months, which makes them a very reliable solution.

You won’t need to talk to a stranger to help you and will take seconds to a couple of minutes to jump your car.

These jumper boxes are definitely a good investment considering what they do. Nobody wants or expects a faulty battery, but when it happens, the sensation is not good.

Having one of these with you when that happens is fantastic, and for that, these are a must have for every driver in the world.