Jumpstart Car the Wrong Way

What Happens When You Jumpstart Your Car The Wrong Way: A Guide for Novice Drivers

You do not need to be a genius to figure out how to jump-start a car’s battery. You simply need a car with a well-functioning battery and jump-starting cables. Connect positive to positive and negative to negative. Unfortunately, things may not always go as planned. There are some instances wherein you might not do it the right way.

When you jump-start your car the wrong way, damage to different car parts can occur. The battery, jumper cables, car electronics, fuses, and sensors could sustain some damage. Don’t forget yourself; burning yourself could also occur. 

That being said, jump-starting your car isn’t normally dangerous. We will explore how to stay safe and avoid dangerous situations. In addition, we’ll discuss what to do when an accident happens. 

Check out this video below for some common things that will happen if you don’t jump-start your car correctly:

Jump Starting the Wrong Way: The Consequences

Each car is a little different, but each has fuses that help protect the car. If an accident does occur, most of the time, you don’t need to be concerned for your safety. The car may sustain some damage, but nothing serious usually occurs that would lead to serious harm.

Damage to Components

In the short video above, damage occurred to the fuse. Luckily nothing else seemed to be damaged. Some cars have spare fuses, so checking your owner’s manual might be helpful.

Damage to the electronic could be worse if more power was added. That’s why the 1st step to jump-starting is to turn off both cars and remove the keys.

Jumpstarting the car the wrong way will cause less damage when the cars are off. Switching the color, putting the red cable on the black (negative) battery terminal and the black cable on the red (positive) terminal, can send power where it’s not supposed to go.

The electrical system may be damaged, including sensors and fuses. The good news is that they can be replaced, and no permanent damage is done.

Damage to Battery

If a battery was connected the wrong way momentarily during a jump start, there would likely be a small amount of damage. But, if the connection persists for a while, the electrical current doesn’t have anywhere to go, and damage to the battery is likely to occur. 

The result of incorrectly connected batteries is that heat is created, gases are generated, and dangerous situations can occur. In this case, I am referring not only to the dead battery that is being jump-started but also to the battery from the rescue car as well.

The result of these two batteries connecting the wrong way could melt/damage either battery. If you have lead-acid batteries, which are the most common type of car batteries, hydrogen gas could be discharged.

This happens when the casing of the battery cracks a bit because of the pressure of the hydrogen gas. If gas escapes, it could explode in this type of situation. If you notice any dangerous situations, get far away (100 ft+) from the cars as soon as possible.

Most people will notice a larger spark when connecting the wrong way (possibly a smaller spark when connecting correctly)  and decide not to connect the cables that way anymore. This dangerous situation usually won’t occur with most people. 

Damage to Jumper Cables

Like the previous situation, incorrect contact with a jumper cable between two batteries for a time will heat up your jumper cables. The wires will heat up and may get damaged.

Strong cables may handle the heat better, but some lightweight cables could start to melt/burn when exposed to this amount of heat. The clamps will get hot, and the solder might not hot the wires securely anymore.

If you notice the heat from the cables, it’s best to disconnect them safely and recheck for the correct and secure connections. 

Damage to Alternator

Sometimes a car has some components that might be on during a jump start. Lights may be on or a stereo. A component that is on might be using the alternator. The alternator can then get a surge or power that can cause damage. 

Because of the high electrical current, which can be too much for many parts of your car to handle, the alternator could overheat. When there is an issue with an overheating alternator, other parts may be affected as well if using the alternator. 

It’s a good idea to make sure that everything is turned off and that anything that might be connected directly to the battery terminal, such as a car alarm, is disconnected. 

To sum up, turn everything off no matter what it might be, disconnect any device that may be connected to the battery, and be aware of items that may be automatically turned on in some situations, such as a radiator fan to cool your car after it is turned off. ​

If your car doesn’t start, put safety first, and you’ll save yourself large repair bills, and you’ll make sure no harm comes to you or anyone else.

How to Solve any Problems Created?

From the short video shown in the introduction, one solution is to change the fuse. 

The fuse can get burnt because of the extreme heat resulting from the surge of electricity. You’ll need to check your fuses and select the fuse(s) that may be associated with the car battery. In most cases, it is the powertrain fuse.

In some cases, the fuses may not be the only electrical part affected. If the alternator is damaged, it may need to be replaced, and it could affect the components that were connected to it. 

If the electrical current is able to get to the car’s computer system, you may need to replace that as well. 

Sometimes the battery is also damaged and no longer functions. It will need to be replaced as well.

Tips When Jump-Starting your Car

In most cases, jump-starting a car will be safe to do, but to prevent any problems, follow the guidelines outlined below:

Steps to Take

  • 1st – Cars: ensure cars are not touching each other
  • 2nd – Cables: Untangle and clean off any grease from the cables
  • 3rd – Electrical systems: Turn off the cars, remove the keys, and ensure all electrical systems are off, including the lights 
  • 4th – Cables: Connect the cables by:
    • 1. Connect the (+)positive cable clamp to the dead battery (+)positive terminal.
    • 2. Connect the other (+)positive cable clamp to the donor battery (+)positive terminal.
    • 3. Connect the (-)negative cable clamp to the donor battery (-)negative terminal.
    • 4. Connect the (-)negative cable clamp to the dead battery (-)negative terminal.  OR, to be extra safe, Connect the (-)negative cable clamp to the ground on your car away from the battery. (If any gas from the battery is leaking, and a small spark occurs, an explosion could occur.)  
  • 5th – Turn on the donor car. Let the dead battery charge for 3-5 minutes. (It depends on how drained it is.) 
  • 6th – Try starting the dead battery car. If it works, keep it on and drive it for about 30 minutes to help recharge. If it doesn’t work, you could try charging it a bit longer and try checking for good connections, as this may be why the battery is not charging. Another thing to try is using a different ground point.
  • 7th – After the dead battery car is running:
    1. 1. Disconnect the (-)negative cable clamp from the dead battery (-)negative terminal OR ground on your car.
    2. 2.  Disconnect the (+)positive cable clamp from the dead battery (+)positive terminal. You can place them on the ground making sure they don’t touch. 
    3. 3. Disconnect the (+)positive cable clamp from the donor battery (+)positive terminal.
    4. 4.  Disconnect the (-)negative cable clamp from the donor battery (-)negative terminal.
  • 8th – You are ready to go if everything is working well.


  • Avoid charging vehicles or machinery that have larger batteries than you or that require more power. Regular cars and trucks should be fine most of the time. 
  • Make sure the cables do not come in contact with any metal surfaces, with each other, or with your skin as you attach them and detach them. 
  • If your battery is cold/ frozen, don’t try to jump-start.
  • If the battery is damaged, cracked, or leaking, don’t try to jump-start it – get a new battery.

Additional Tips

  • Take a look at your jumper cables and make sure that they are in good condition. They must be free from rust. If they are already worn out, even if you connect the clamp on the right terminals, it might not work well.
  • Read the manual before you start. If you may have information to help, you jump-start your car the right way for your specific model. For instance, newer car models might need to attach lugs before you jump-start.
  • Make sure that the car is in the park. The cars should be out of traffic and avoid any dangerous parking situations.
  • Protecting your hands with gloves and eyes with goggles could help avoid any injuries if something goes wrong. 
  • Perform an inspection on both of the batteries before you start. Clean the terminals if needed to create good contact points for the cables.


When you jump-start your car the wrong way, there are many things that could possibly happen. The battery, jumper cables, and electronics will be damaged, including the fuse and the sensors. There is even a risk of explosion when the problem is at its worst. Nonetheless, most of the time, the problem won’t be too severe and nothing that could cost an arm and leg.

Once you realize that you did the wrong thing, you may be able to fix the problem on your own. In most instances, you need to check the fuse. Chances are, one of them is burnt. You can buy a replacement for this, and your car will be up and running in no time.

Have you ever tried using a battery charger to get your car to start? This might help you figure out if your battery is salvageable or not. If you are still not sure why your battery is dead, try reading this article