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How Long Can a Car Battery Sit Unused? (Read This First!)

When you leave your car unused for a longer time, the battery becomes one of the major concerns. But how long can a battery last when not used?

Is there any way to keep your battery alive when you are not using it? This article will answer all the questions related to an unused car battery.

How long can a car battery sit unused?

An average car battery will go flat within two weeks being unused, although many factors affect the time. When unplugged, a new and well-conditioned battery can live about 2-3 months. You can keep it alive by driving 5-10 minutes every week or charging your battery 2-3 times a month.

When a car sits for a long time, it gets damaged over time like most other things. But a flat car battery is the biggest problem of not driving your car for long.

A car battery doesn’t even give you a long time; some battery takes only a week to go bad when connected. Most car batteries can survive two weeks without going flat. A new battery can last some more days when not used.

But what causes your battery to go bad? First, let’s talk about batteries. Most modern cars use the lade-sulfate battery as a power source for internal computers and other functions of the vehicle.

When you drive the car, the battery gets charged. But when you don’t drive your car for a long time, the battery doesn’t get charged.

Whether the battery is getting charged, internal functions always use the battery. Modern cars never sleep. The internal computers constantly monitor the system, which costs a little energy. The battery can backup the system for one to two weeks.

So, does disconnect the battery help the problem? Disconnecting does help a bit but certainly doesn’t solve the issue. A disconnected battery can survive 2-3 months when stored adequately without getting damaged.

The sulphuric acid breaks and creates sulfate crystals when you leave a battery sitting for a long time without using it. We will discuss the solution and other essential information, but first, let’s learn how long your battery can live in the conditions below.

On a shelf:

Sealed lead-acid batteries last about one year when stored properly at room temperature and charged every three months.

In winter:

When the battery is connected to the car, it can last about 10-15 days when not used in winter.

How long can a new/modern car battery sit unused? Can a car battery sit unused for 3 months?

A modern car battery can sit 2-3 weeks max without being used. The most modern car is dependent on lead-sulfate batteries for internal power. The technology is moving too fast, but battery technology still struggles to keep up with the new age.

Modern cars have several computers, AC, radio, lights, security systems, displays, etc. Some functions keep working even when you are not using the car. Those functions use a little energy.

But when the car is not being used, the battery doesn’t get charged and fails to support the functions. Leaving a car idle for 2-3 weeks is enough to damage the battery.

You can keep the new car battery unused for three months only when you disconnect the battery from the car and adequately store it a room temperature.

After three months, you will have to charge the battery again to keep it in good health. Older batteries may not survive that long.

A battery can last about 4-7 years, depending on your use and environmental conditions. If the environment gets too hot or too cold often, that can affect your battery life.

Can a car battery go flat from sitting? Do unused car batteries expire?

Yes, car batteries can become flat from sitting. A flat car battery is often not recoverable, and even if you recover the battery, most of its life is gone. The battery will not last long once you revive the battery from being flat.

Unused car batteries expire within a few weeks if connected with the car. However, if you want to keep the battery alive for a long time, like two to three months, you will have to store the battery in the right way.

If you want to keep your battery healthy for six months or one year, you will have to charge the battery every 12 weeks and keep it on the shelf. If you can’t charge your batteries, you can use an inverter battery to keep your battery alive for six months to one year.

Keep reading to learn how to keep your battery idle for a long time without charging it regularly.

What happens if a car battery sits too long?

When you don’t use your car for too long, the car battery gets bad fast. After the battery, the car tire and other vehicle parts start getting damaged. We will discuss what happens when you keep your car battery sitting for too long without disconnecting the battery.

The battery gets flat:

When you leave a car without disconnecting the battery, the system uses the power, but the battery does not get charged as you are not driving the car or charging the battery in another way.

When the car sucks the last bit of energy out of the battery and remains in that condition, the battery’s life reduces drastically.

When that happens with a car battery, you can fix some of the batteries and use them for some time, but most of the battery does not work appropriately after restoring the flatness.

Sulfate crystals are formed:

When you leave the battery without any charge or overcharge, the sulfate ions break down and form crystals which cause flat batteries. Those conditions are fixable, but the older battery does not work consistently once crystalized.

The systems stop:

When you do not use your car for a long time, the battery loses its last charge within two to three weeks. And then your battery can not support the functions of your car that never stops working, such as your car clock and many other sensors.

How long does a car battery last without driving? How long will a car battery last if disconnected?

A car battery can last 2-3 weeks without driving, but you should never leave your car or battery unused for more than one week. Many poorly-conditioned cars don’t last more than a week when not used.

In the recent pandemic, many people faced this type of issue related to their car battery as they didn’t have to drive their car to go to work. If those situations appear, you can fully charge your battery and disconnect the battery with the car.

A disconnected battery can last about 2-3 months if stored correctly with a full charge and at room temperature. Let’s discuss the different options to store your battery while keeping it alive.

The first way is to drive the car once a week for at least 5-10 minutes. The second way is to disconnect the battery, store it at room temperature, and charge it with other battery chargers every 12 weeks.

The last way is to connect the battery with an inverter battery, and you can get a healthy battery even after a year. In the next section, we will discuss how to store a battery.

How to store a car battery when not in use?

Storing a car battery for a short time, like one to two months, is easy. But for longer storing time need some different arrangement. Here we describe two different ways to keep your battery without any issues.

Storing in shelf:

  • Disconnect the battery from your car. Remove all the wires safely with the right tools if needed.
  • Clean the battery with a cloth. Now, cover the plus point with a red cap.
  • Store the battery on the shelf in the dark, and the shelf temperature should not change often.
  • Charge the battery every 12 weeks to store it longer.

If you have no scope to charge the battery and want to minimize hustle, follow the following method. For this, you need an inverter battery.

With an inverter battery:

  • Remove your battery and get some wires and clamp to connect the battery and inverter battery.
  • Use the red wire and clamp to connect the plus of the inverter and the car battery.
  • Use the black wire to connect the minus of the inverter and battery.

Remember, the inverter battery needs 12 volts and a lead-sulfate battery.

Final Thoughts

Most batteries can survive about 2-3 weeks when connected with the car, but you should not leave your battery unused for more than a week to be on the safe side. By disconnecting the battery from the car, the battery can last about 2-3 months without charging when stored correctly.