Can a Battery Drain with Negative Cable Disconnected?

If you’re going on a vacation or looking to leave your home for some weeks or months, there is one thing you ought to do which is disconnect your car’s battery. This will prevent the electrical systems connected in your vehicle, such as the onboard computer, from running despite not driving it. Disconnecting the negative battery cable will prevent your battery from draining.

The electrical systems will drain your car’s battery which means that the car may fail to start when you’re back. You can opt to jump-start your vehicle, which will leave your battery life and that of the alternator reduced.

When you jump-start a car, you make the car’s alternator work hard, which, in this case, powers the battery. Alternatively, you can buy a trickle charger that will slowly charge your battery when left connected. However, a trickle charger isn’t a cheap alternative. Overall, disconnecting your car’s negative battery cable will save you the cost of having to replace your battery.

Car battery drainage is common, especially in newer advanced cars. This results from the many electronics and modules present in the car. These features cause the battery to drain as fast as within a week of inactivity.

So, how do you prevent your car’s battery drainage? The only way to do this is to disconnect the battery cable. You can do this by disconnecting any of the terminals.Can a Battery Drain with Negative Cable Disconnected

What Happens When You Disconnect the Negative Battery Cable?

Disconnecting the negative battery cable in your car disconnects the battery from your vehicle chassis. This means that all the electronic systems and settings in your car are disconnected, so your car’s battery won’t drain.What Happens When You Disconnect the Negative Battery Cable

In addition, disconnecting the negative cable saves you from the risk of a short-circuit. It might happen by chance if you touch your spanner against a metal component or bodywork while disconnecting the positive battery cable. There is no current flow when you disconnect the negative battery cable since you have grounded the ground clamp.

Following this, shorting the positive battery cable to the ground will produce no current flow since the current lacks a negative cable return path.

Furthermore, disconnecting the negative battery cable is an easy task requiring caution. This is because you are working around a battery that contains acid which may be dangerous if you don’t exercise necessary precautions. Therefore, here is how you can disconnect the negative battery cable safely.

First, remove the negative port cable. As you do this, ensure that the negative cable end and the positive cable end don’t touch to prevent injuring yourself and damaging your car. In addition, when you disconnect the negative battery cable, ensure that it’s secured so that it doesn’t come into contact with any positives or the ground.

You can do this by wrapping the end of the cable using a Ziploc bag, so it doesn’t come into contact with anything while you’re away.

Moreover, familiarize yourself with the car’s settings before disconnecting your battery. This is crucial because disconnecting your battery will reset all the settings and the electronic systems in your car. This means that when you reconnect the battery, you have to reset the electronic systems and settings as well.

Read Also: How To Test Alternator By Disconnecting The Battery

Is it Okay to Just Disconnect the Negative Terminal?

You can either disconnect the positive or negative terminal. One of the terminals will suffice and result in an open circuit. This means that no current will flow, and your battery won’t drain.Is it Okay to Just Disconnect the Negative Terminal

However, to avoid shocks, injuring yourself, damaging the car’s alternator, and many other harmful things, disconnect the negative battery cable first. The negative battery cable is the ground of your car; disconnecting it is a safety precaution that will save you from having to experience the full power which surges through your vehicle.

Why Should You Disconnect the Battery While Storing Your Car?

Following are some of the benefits of disconnecting your car’s battery when leaving it for longer than a week.

Saves the Battery Life

As mentioned earlier, when you disconnect your car’s battery, you increase its life. Your car’s electrical systems, such as the onboard computer and clock, tend to drain your battery entirely if the battery isn’t disconnected; therefore, if you leave the battery unattended for long, your car’s battery damages forcing you to replace it.

Saves Money

Disconnecting your car’s battery saves you the cost of having to replace it with a new one. Buying a new battery isn’t cheap. However, if your battery completely drains, you have the option of jump-starting it, which may cause damage to your car’s alternator as well as damage your car’s battery. This is an additional cost, and therefore, it is better to disconnect your battery since it will save you money.

Alternative Solution

An alternative solution to disconnecting your car for storage is to buy a trickle charger. When you leave it connected to your car, it will charge it slowly, and your battery will still be intact when you return. However, this isn’t a cheap option either, but it’s better than failure to disconnect your battery for long.


What Is the Color of The Negative Battery Cable?

The negative battery cable is black in most cars, while the positive battery cable is red. However, if your car company doesn’t follow this standard, you can refer to the user manual or look it up on the internet.

Should I Disconnect Both the Negative and The Positive Terminals?

You can choose to disconnect both terminals or one of them. In this case, if you decide to disconnect one of them, let it be the negative battery cable because the negative battery cable is the ground. Therefore, you’ll be safe from shocks and also prevent damage to the car.


If you’re planning to store your car for a long time, disconnecting the negative battery cable is an excellent way to prevent your battery from draining. However, follow safety procedures during the battery disconnection process to avoid hurting yourself and damaging the car.

It is especially important to disconnect the negative cable first because if you disconnect the positive battery cable first, the wrench may inadvertently come into contact with other vehicle parts, which may blow a fuse and damage the battery and other car parts.

Not to mention, the maximum time you should disconnect your car’s battery is six months. However, you can charge your battery for a longer period for it to last longer.

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