What Happens When You Connect A Motorcycle Battery Backwards?

Published on: June 3, 2022
Written by Liam Jaxon / Fact-checked by David Rowan

What happens when you connect a motorcycle battery backwards? Does it damage the battery or cause any harm to the motor system? 

When you connect the positive to a negative terminal, it causes a hazard to your motor vehicle. Whether it is a car or motorcycle, when you reverse the polarity of the battery, it causes trouble to the battery. Additionally, it harms the vehicle and its electronic system as well.

what happens when you connect a motorcycle battery backwards

But what problems can the reversed polarity of the battery cause? Let’s find out below. We will also share if connecting the jumper cable in reverse can cause any trouble to the system. Keep reading throughout the article to know more.

What Happens When You Connect a Motorcycle Battery Backwards?

Connecting a battery backward means putting the positive on the negative terminal and vice versa. It is a very common mistake during the battery exchange, especially if you are not an expert.

So, if you connect the battery reversed, you will notice electric sparks. The sparks may spread throughout the connections that are connected by the battery. This will affect the vehicle’s complete electric system. If your car or motorcycle is not protected with a fuse to prevent events like this, you will probably lose the battery.

When you connect the battery backward, the electricity flows through the system reverse. This might affect the ECU or your car’s Engine Control Unit. Since the ECU has diodes, a reversed battery will interrupt the workflow of the electric system connected with it. So, the effectiveness of your car’s electronic system will be destroyed.

What Major Problems May Appear When You Connect a Battery Backwards?

A battery must be connected to the car with the right cable- The red cable for the positive terminal and the black cable for the negative terminal. Though there are clear signs of a battery’s positive(+) and negative(-) sides, it is easily mistaken when you are in a hurry. And that can damage your battery at a deeper level. So, what problems might your vehicle face when the battery is reversed? Let’s look below.

i) A Massive Spark

Reversing the battery accidentally can cause a huge spark.

ii) Fire Hazard

The spark can lead to a fire hazard burning down the internal cables and even your entire vehicle system.

iii) Battery Damage

If reversing does not cause any spark or fire due to a low battery charge, leaving the battery in this state for a long time will gradually damage all the connectible that can not handle backward electric flow. Eventually, this will ruin your entire motor battery.

iv) Damage the Sensor and Computer System

If the motor system has a fuse protector, your vehicle will survive the backward connection. Otherwise, it will damage the onboard computer system of your vehicle.

What Happens When You Reverse the Jumper Cables on a Battery?

Did you know that reversing the jumper cables of a battery will create a huge massacre as switching the battery terminal? Many people use jumper cables to wake up a dead battery. But it is very common to put the cable in the wrong way. This can lead the batteries to damage. You may notice the following things if you reverse the jumper cables to wake up a dead battery-

i) Damaged Jumper Cables

Reversing the jumper cables on a battery can damage the jumper cable itself. If you put the negative cable on the positive terminal or the opposite, it will create a large electrical outflow that the jumper cable can not handle. As a result, the cables will heat up extremely and burn the covering. Additionally, this can burn down the clamps that hold the jumper cables in place.

ii) Damaged Battery

Since you are using another battery to jump-start your car’s battery, when you connect the jumper cable in reverse, it will damage both batteries. So, when you want to jumpstart the car battery, be aware of connecting the jumper cables in the right order. If connected incorrectly, it will result in a massive spark and burn down everything. Also, if it is a lead-acid battery, there might be hydrogen gas clouds due to this sudden spark and excessive heat production.

The hydrogen gas produced from the battery is explosive. You must recharge the battery in the open air. Even though it is not a toxic gas, it can be highly explosive in a congested area. So, if you wrongly put the cables on the battery, there are chances that it can lead to an explosion and lead you to a serious injury.

iii) Damage the Fuse

Incorrectly plugging the jumper cable can also damage the fuse. The fuse plays a great role in protecting the electrical system from being destroyed by a sudden power surge in motorcars. When you keep the engine running while recharging the battery, this may lead to fuse destruction.

iv) Damage to the Electronic Support System

Modern vehicles have electronic sensors and computers to support automotive functions. When you reversely plug in the jumper cable, the sudden power surge affects the onboard computer system and damages it. Sometimes the damage is irreparable, and you will have to change the system.

Also, holding the jumper cables’ ends together is dangerous too when it is hooked to a battery. If you hold together the ends of two jumper cables, it will create a spark.


What are the potential risks of connecting a motorcycle battery backwards?

Connecting a motorcycle battery backwards can cause serious issues, such as damaging the electrical system and even starting a fire. Following the correct steps in a motorcycle battery charging guide is crucial to avoid any potential risks and ensure the safety of the bike and the rider.

What are the Consequences of Connecting a Battery Backwards?

Connecting a car battery backwards can have serious consequences. If the car battery polarity is reversed, it can damage the vehicle’s electrical system, lead to a short circuit, and even cause the battery to explode. It is important to always double-check the polarity before connecting a car battery.

1. What Happens When You Connect a Battery Wrong Way?

Reverse connecting a motor battery can cause damage to your vehicle’s electronic system. Besides that, when you connect the battery in the wrong way, it can burn down the fuses and the entire car.

2. What Happens When You Connect a Negative Battery Terminal to a Positive?

When you connect a positive terminal to the negative, it will create a spark. Connecting the terminals in the wrong way can leave the electric system useless. Reversing the polarity when charging a motorcycle battery can even cause an explosion.

3. What Happens When You Reverse Polarity of the Charger Cables on a Motorcycle Battery?

Your motor battery needs regular charging. When you charge it with a battery charger, it is necessary to plug the cables in the right direction. If you put a charger in reverse, it can damage the battery. The battery would not hold a charge. This can even result in an explosion. Then you will have to buy a new battery for your vehicle.

4. Did Hooking Up My Battery Backwards Fry Everything?

Yes! If you hook up your motor battery backward, AKA positive on the negative, it will most likely fry up everything. So, if you accidentally hook the positive terminal on the negative, that might have burned your motor system.


What happens when you connect a motorcycle battery backwards? Well, it just does not ruin the battery; it damages much more than that. This simple mistake can lead to a battery explosion. This can cause serious injury and destroy your car’s engine compartment completely. Also, it affects the electronic system of the vehicle and damages the battery also. So, reversing the polarity on a battery can bring you a whole lot of trouble.

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About This Writer

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Hi, I am responsible for the 'Homeowners Power Solutions' category. My name is Liam Jaxon and a licensed technician with 7 years of experience in vehicle batteries, electrical gadgets, and home appliances. My working experience in different residential & light commercial electrical sectors and the automobile industry helped to acquire vast knowledge in this industry.

Hi, I am responsible for the 'Homeowners Power Solutions' category. My name is Liam Jaxon and a licensed technician with 7 years of experience in vehicle batteries, electrical gadgets, and home appliances. My working experience in different residential & light commercial electrical sectors and the automobile industry helped to acquire vast knowledge in this industry.

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