How Long Can a Car Sit Before the Battery Dies [Explained]

For one reason or the other, you may leave your car parked for a long time. But before you do that, have you asked yourself how long the battery will last before it dies?

Whether you park your car because of winter weather or leave it at the airport, you should ask yourself this question. Unfortunately, there is no direct response to this question.

New batteries can last 4 weeks or more. But as the battery ages, its ability to hold electrical charge comes down. They can remain charged for a week or two if the car is parked.

But why do car batteries die when you park the car for a long time? The reasons for that are many. That is the focus of this article. Continue reading for detailed information, including tips to keep the battery last longer.  

What Does a Battery Do in a Car?

Your car battery is an essential component of the vehicle. Without it, the vehicle is virtually inoperable. But what does it do?

When you start the car, you need electrical power to run the starter motor to crank the engine. That power comes from your car’s battery, which explains why you can’t start the car with a dead battery. It powers the ignition system.

Once the engine is started, it drives the alternator, which generates electrical power to recharge the battery and run other accessories. But even with that, you will still need your car’s battery.

A car battery also runs car electricals, especially when the engine is not running. These include radios, vehicle lights, a car’s computer system, alarms, heated seats, and many more!

What happens when the auto-shutoff stops the engine at a stop sign or traffic? The battery continues to warm your seat and power all electronics. Generally, your car needs a battery to operate efficiently and conveniently.

When the battery is dead, the can needs jumpstarting every time you stop the engine. The engine can also stall.

How Long Can a Car Sit Before the Battery Dies?

As mentioned, your car battery can last for two weeks or slightly over four weeks, depending on the age and battery type. Aging batteries are weak and may only take two weeks or less to die. Some may not take even a day or two. That is why you may need to jumpstart your car very often.

Car batteries are made of individual cells which wear out with every charging and discharging cycle. Over time, they become weak and eventually die. A dead battery cannot store electrical charge!

But why do even new batteries die if the car is not driven for a long time? The reason varies, and we will explain each factor in the next section.

Why Does a Car Battery Dies After Sitting for a Few Days?

Your battery can last only 2-4 weeks if a car sits for a long time without being driven. What causes it? Why does it drain, yet you are not using it?

The car battery may drain out because of the following reasons:

1. Leaving the Headlights On

You may not know it, but you can leave your car without turning the headlights off when you get out of the car. Fortunately, new vehicles have a system that automatically turns the headlights off after some time.

But if your car does not have that feature, the lights will remain on until the battery drains out or until you turn them off. Headlights can drain the battery faster than a week. In fact, if your battery lasts for more than a day, it is likely new and fully charged.

2. Temperature Changes

Temperature changes can significantly affect your car battery. The battery cells are designed to work best under a narrow temperature range.

Most batteries will not withstand extreme cold during winter months or excess heat during summer months. Even if they are charged, these harsh weather patterns can drain much faster.

Newer batteries are more immune to temperature changes and may last longer. But if you have an old or aged battery, it can even run flat if you leave it overnight in the winter cold.  

3. Parasitic Draining

A parasitic drain entails anything that draws battery power when you switch off all the accessories and lock the car door behind you. The list is long, but the most common include car alarms, car tracking systems, car computer systems, dashboard cameras, and security and safety systems.

Parasitic drain can also be caused by faulty battery sensors. The car battery management system depends on the data from this sensor to check and monitor the battery’s health status. A faulty sensor can cause electrical shorts that drain the battery.

Any electrical short in your car will still drain your battery, even if you think you have turned off everything.

The mentioned factors can drain your battery much faster than expected. Parasitic rain can even kill the battery in just a few hours.  

4. Letting Accessories Running When the Engine is Stopped

Some people also like listening to the radio or having other accessories on after turning off the engine. Such systems get power directly from the battery, which is not being charged since the alternator is running.

Leaving your accessories on does not necessarily belong to this section, but it is worth mentioning. Once you shut down the engine, turn off all other accessories and lock your door to leave the battery charged.

Tips on How to Keep Car Battery Charged When Not Used

You can extend the duration of your battery if you observe some tips. It can vary from car brand and model, but the following is likely to keep the battery charged for longer when the car is parked.

1. Remove the Battery from the Car

It is hectic disconnecting your dashboard camera, car alarm, or even turning off your car security systems. And how else are you supposed to stop the parasitic drain resulting from electrical faults?

The best way to keep your battery charged is if you will not be using it for a long time if you remove it. Open the hood and unscrew the battery from your vehicle. This will reset some systems, but it will at least keep your battery charged.

Once you remove the battery from the car, keep it well maintained in a room with a temperature range from 40 to 60 degrees Fahrenheit. You can also buy a battery box to help regulate the conditions.

Your battery can last about 2-6 months if taken out of the vehicle and stored under optimal conditions.

2. Get a Battery Maintainer

A battery maintainer is viable if you have a garage with a socket. This device monitors your battery’s charge level and starts to charge it when it drops below the minimum. The charging stops when the battery is fully charged.

Using a battery maintainer is the best option if you don’t want to remove the battery from the car. This way, your battery will remain charged for months.

3. Disconnect Alarm and Other Security Systems

Disconnecting your accessories, such as alarm and security systems, can put your car at risk. But it can extend the battery life. You can call a technician to do it if you are not a DIYer.

However, disconnecting the alarm and security systems is not a sure way since a parasitic drain can still run the battery down.  

4. Disconnect the Negative Battery Terminal

Disconnecting the battery negative terminal interrupts the flow of electrical current. That means the accessories and parasitic drains are cut off. So, your battery will last longer.

However, disconnecting the battery resets the system. You also rely on the car’s battery conditions box to keep it, which may not be ideal. High temperatures and colds may still discharge it.

5. Drive the Car Weekly for At Least 15 Minutes

If you are going on vacation or something, you can leave your car key with a trusted person to be driving your car for at least 15 minutes every week. This helps to recharge the battery, helping it to maintain its charge.

Signs of a Weak or Dead Car Battery

You should know when the battery is nearing the end of its service life. It will show you signs, after which you can take it for analysis before replacing it.

When a car battery becomes weak, you will notice one or more of the following:

1. Dim Headlights

Car headlights require electrical power to shine brightly. If the brightness has significantly reduced, the battery may be weak.

If your light dims immediately after turning off the engine, the battery may need replacement.

2. The engine Won’t Crank

Starting the engine requires an enormous current from the battery. A weak or dead battery cannot just provide it, making it impossible to crank the engine.

A weak battery will also make jumpstarting your car more frequent. It is a sign that you should budget for a new one sooner rather than later.

3. Clicking Sound When Starting the Car

A clicking sound indicates that your starter motor does not receive enough power from the battery. It can be due to corrosion at the battery terminals, loose connections, or a weak battery. Ensure the first two are ruled out before you replace the battery.

4. Battery Light Comes On

Your car battery should have a minimum voltage of 12.5V if healthy and charged. A 12.4V is considered weak but is still okay. But anything lower than that will trigger the battery light.

The battery light can also come on if the alternator is faulty or there is a problem with the charging system. So, don’t victimize the battery without further diagnosis.

5. Electrical Accessories Not Functioning Well

Your electrical accessories require enough power to operate well. If the battery is weak, it may turn off, one after the other.

If the accessories and dashboard go off soon after turning off the engine, your battery is weak. It possibly requires replacement.

FAQs

How do you start a car with a flat battery?

You can jumpstart your car if the battery is dead. Alternatively, you can call a roadside service to help start the car and drive off if your battery is flat.

How many years do car batteries last?

The lifespan of batteries varies depending on the battery type and maintenance level. It can last about 2-5 years. You get a longer service life if you keep the best driving habits, such as avoiding short trips that leave the battery half-charged.

How much would it cost to replace a car battery?

Fortunately, replacing your car’s battery won’t break your bank account. It ranges from $45 to $25, depending on many factors, such as the brand and where you buy it. Batteries for heavy-duty tracks are also more expensive than compact cars.

How long can a car sit without killing the battery?

It depends on the age of the battery and the amount of charge. A new, healthy, fully charged battery can last for 4 weeks without running flat. But old batteries can barely do 2 weeks.

How often should I start my car to keep the battery charged?

You should drive your car for 15 minutes at least once a week to charge the battery. The longer you do it, the better it is because the battery will be fully charged.

How do I keep my car battery from dying when not in use in winter?

Park your car in the garage to protect it from the cold winter weather. Alternatively, you can remove it and store it separately under optimal conditions. Extreme cold temperatures can damage the battery cells.

Final Remarks

Drive your car at least once every week for 15 minutes or more to keep the battery healthy. Alternatively, you can use a battery maintainer if going on vacation. You can also take it out and store it in a battery box indoors if unsure of the return date.

Leaving the battery in the car when sitting there can damage your battery. Most batteries will last about 2-4 weeks before they become dead. Unplugging your accessories can help extend this period, but not a sure way to keep your battery healthy.