Can I Connect a Negative Battery Terminal To a Positive?

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To ensure that you don’t make mistakes, car batteries (and every other type of battery) come with positive and negative terminal markings. This is to clearly show you where you need to append/fix/connect the positive and negative cables meant to be used on the battery.

But, what if you make a mistake and connect the terminals wrongly? What happens if you connect a negative battery terminal to a positive?

The most common scenario to occur is excessive “sparks” that may even cause a fire outbreak or explosion – depending on several factors. Aside from that, other potential damages may occur to your car’s electrical system if you connect the battery terminals incorrectly.

This article explains the various possible scenarios that could occur!

Understanding Car Battery Terminals Markings (+VE and -VE)

Car batteries are designed to indicate the positive and negative terminals. The Positive terminal carries a +VE marking, or simply a “+” sign, while the Negative terminal carries -VE marking, or simply a “-” sign. These markings are to tell you where to connect your jumper cable’s positive and negative terminals.

Well, the markings are not only for jumper cables; if you remove your car’s battery – probably to charge it externally – when you want to install it back, the markings would help you connect the battery cables (from the alternator) to the respective positive and negative terminal.

Each of the battery terminals carries a 12V electricity current/charge. In literal terms, the positive terminal uses +12V, and the negative terminal uses -12V. If you connect battery cables (or jumper cables) wrongly – to the wrong terminal – you’d end up damaging some serious “stuff” in your vehicle.

What Happens If You Connect a Negative Battery Terminal To a Positive?

Can I Connect a Negative Battery Terminal To a Positive

Here’s a practical explanation of what could happen if you switch the battery terminals. The moment you switch the terminals – and they come in contact with the battery’s posts, you’d see serious sparks of fire (especially if the battery is fully charged).

In some rare situations, you may experience an electric shock – which typically happens if any part of your body is touching a metallic part of the car as at the time the sparks ensued.

Such mistakes (connecting battery/cable terminals to the wrong battery post) can cause a serious power surge, which could damage most of the electrical components of the car, including the ECU (Engine Control Unit).

Of course, all the dashboard lights would go out, and if you connected an external electrical appliance, such as a car refrigerator, it could be affected too. Also, fuses, spark plugs, and other components of the car that uses electricity could get affected.

Notwithstanding, some vehicles come with a fuse that could remedy these types of mistakes; so, when the power surge occurs, instead of your car’s electrical components getting damaged, the fuse would simply break and stop the current flow.

How To Connect Battery Terminals Correctly

You should connect the positive terminal before connecting the negative terminal; well, you may still see small sparks. Also, check if the battery is off-gassing so you can be more careful.

When a battery is off-gassing and you connect the terminals wrong, the sparks that may occur could catch up with the gasses emitting from the battery; thus, causing an explosion, or a more serious fire outbreak (hazard).

Most importantly, if you’re jumpstarting a car, connect the negative “clamps” last; however, after the jumpstart, remove the negative clamps first, before the positive clamps.

Furthermore, when removing the cables, don’t allow either of the positive clamps (the one on the bait car or the one in the car with the dead battery) to touch the chassis of either car, the ground, or the negative clamp while the other positive clamp is connected.

In essence, you need to carefully remove the positive clamps from both cars, ensuring that the clamps do not touch anything or the ground during the removal process.


So, what happens if you connect a negative battery terminal to a positive? There’d be sparks, and depending on quite many factors, the sparks may be serious or light.

If the sparks are serious, most electrical components in the car might get affected; meanwhile, the battery itself may damage immediately as a result of such a mistake.

Generally, you should always connect the positive terminals before connecting the negatives. But while removing, remove the negatives first before the positives; this applies to both jumpstarting and uninstalling/reinstalling a car’s battery – for and after a charge. Hopefully, this article answered your question comprehensively.

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