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Which Side Of The Car Battery Is Positive? Decoding the Sides of Your Car Battery

Car battery with red positive post and blue negative post.

Do you need to jump start a dead battery? Or are you just curious about your car battery? Here's a handy quick guide for figuring out which side of car battery is positive.

The positive terminal of your car battery will always have a plus sign (+) marking near it. It will almost always be colored red at the base of the terminal. The wire attached to the positive terminal will usually also have a cover with a red plastic body.

The positive and negative sides of a battery are usually easy to tell apart. It's important to know which one is which, since mixing them up can be dangerous.

Table Of Contents [show]

    Car battery with red positive post and blue negative post.
    Car battery with red positive post and blue negative post.

    Which Side Of The Battery Is Positive And Negative?

    The positive and negative terminals are color coded and use different markings so they are easy to tell apart.

    The positive terminal is marked with a plus sign (+) and is colored red. The negative terminal is marked with a minus sign (-) and is colored black.

    A new battery will often have colored felt pads at the base of each of the battery terminals to help tell them apart. These pads also help prevent corrosion of the battery cables and posts.

    If you are having trouble seeing the colors or markings on your battery, you can still figure out which is your positive and negative terminal.

    Car batteries always have cables that run from the positive terminals to the starter motor and the alternator. You can trace these cables from your battery to tell the posts apart.

    What Color Is Positive On A Car Battery?

    Red is always the color of the positive terminal. Some batteries have cables that are the same color, but there will usually be some sort of red coloring somewhere on the positive.

    It's very important to know which one is which. If you connect the cables to the wrong terminals, you can destroy even a good battery.

    You also need to be able to tell them apart if you have to use jumper cables to jump start a dead battery in your car.

    Jumper cables will almost always have a red positive cable or a red stripe on the positive cable. They must be hooked up to the right terminals to work correctly.

    Jumper cables hooked up to a battery - black clamp on negative and the red clamp on the positive post.
    Jumper cables hooked up to a battery - black clamp on negative and the red clamp on the positive post.

    Is Black Positive Or Negative On A Battery?

    Black is always the color of the negative terminal. The negative always uses a black cable too.

    Are Car Battery Terminals Always On The Same Side?

    The two terminals are not always on the same side of the battery.

    Some manufacturers will have the positive terminal on the left side, and the negative terminal on the right side. Others will have them in reverse order from this.

    It's a good idea to rely on the markings and colors on the battery instead of assuming that the positive side and negative side are always the same.

    Positive Or Negative First When Connecting A Battery?

    The positive side always needs to be connected first on your vehicle battery.

    The cables must be put on in this order. Otherwise, you can cause sparks and risk electrocution or causing a fire.

    Your car insurance may not cover damage caused from improperly hooking up your battery.

    If you have to jump start a dead battery, jumper cables must always be hooked to the positive terminal first as well. Hooking to the wrong terminal can damage the battery.

    The negative cable for the dead battery should be hooked to a metal ground, like an unpainted part of the engine block.

    The negative cable for the donor vehicle can be hooked to the negative of the charged battery.

    Do You Connect Red Or Black First?

    You always connect the red cable first.

    Why Do You Connect Positive First?

    The positive post should be hooked up first because there is less risk of getting shocked or causing sparks.

    When you connect the positive cable first, it ensures that the current from the battery will flow into the cable and not into anything else close to the battery terminal.

    The negative battery cable acts as a ground for the vehicle, and completes the electrical circuit once it's connected.

    If the negative cable is attached first, then the circuit will become live as soon as anything metal gets close to the positive terminal.

    This means that if you accidentally get close to it with a wrench or anything else metal, you may get shocked.

    Why Do You Take The Negative Terminal Off First?

    You always take the cable off of the negative battery terminal first in order to disconnect the ground and break the circuit of the vehicle.

    When you take away the electrical ground, the positive cable can be safely removed without risk of arcing or electrical shock.

    Disconnecting jumper cables from a battery.
    Disconnecting jumper cables from a battery.

    What Happens If You Remove The Positive Terminal First?

    If you remove the positive side first, then your battery may arc from the terminal to the cable.

    This can cause a short circuit that can damage your electronics or cause a blown fuse in your car. A bad enough short circuit also carries a risk of causing your battery to explode.

    Battery acid is highly corrosive, so this can be extremely dangerous.

    Not only that, but the current from the battery may also decide to run through your body if you touch any other metal surface of your vehicle while disconnecting the positive side.

    Will Car Battery Drain If Negative Cable Disconnected?

    Your car battery will begin to slowly drain current if the negative battery cable is disconnected. This process is known as "self-discharge."

    However, the amount that will drain from the battery is only 5 to 15 percent every month it is left unhooked. A fully charged battery can last for a while like this.

    To compare, the amount that is drained from the battery by the electronics of the car is around 20 percent in a week if the car is not cranked regularly to recharge the battery.

    If you are planning on storing your car for an extended period of time and don't want to remove the battery, then removing the negative cable is a good alternative.

    Otherwise, you will almost certainly have a dead battery next time you try to crank your vehicle!

    Can I Leave My Car Battery Disconnected Overnight?

    You can leave your car battery disconnected overnight without worrying about a dead battery.

    The downside of doing this is that your vehicle electronics will lose all of their stored information. The battery provides power to all of these components.

    Your car's computer will have to relearn all of its programming, such as the proper fuel/air mixture and engine timing.

    A newer vehicle will also have to relearn things like transmission shift points, which can cause rough driving while this happens.


    Car batteries carry a lot of electrical charge, so it's important to make sure you handle them correctly and connect them the right way.

    With a little basic knowledge, your car can have a good battery with a long life ahead of it!