How Long Can You Leave A Car Without Starting It?

There are many different factors to consider when not starting your car for a long period. I have seen older cars start right up after sitting for 25 years with just a new battery and flushing the lines and adding new fuel. If it’s an older car, it can sit a lot longer than newer cars because the rubber and plastic parts do not do well with age.

The truth is no matter what engine you are using, gas or diesel should be started at least a minimum of one or two times within a month. This prevents the seals from drying out. How much harm can come to your car when you leave your car running?

What is Idling?

Leaving your car running after it’s been started is known as “idling”. It means when you start the car but you are not moving. Most people have their car in Idle at one point or another throughout the day. For instance, it occurs often when:

1. You’re stuck in traffic, but turning off your car is unnecessary because you know you will be moving momentarily.
2. You park your car and run into a gas station and it’s unnecessary to turn off the car.
3. Lastly, during a cold morning, you run outside to turn on your car before driving to work and let the car heat up.

Even though many people use idling in many different situations, is it truly worthwhile?

What Happens to Your Car When Idling?

Simply, your car engine is running while your car is idling. However, It still uses a small amount of gas to maintain the car running. When your engine is running many other processes are continuing to be used. For example:

1. Battery is being drained while it’s being idled.
2. The Heat or AC is being used.
3. The engine is keeping warm.

Therefore, If you have ever heard the myth about idling your car for a long period of time damages the car, don’t worry. It’s not true.

Outcomes to Your Car for Idling Too Long?

If you leave your car running too long, you might have a few side effects:

1. As mentioned, your car engine continues to use fuel as long as the car continues to stay on. Your car’s battery is being drained faster than the alternator can recharge the battery. When the car idles the engine and alternator are running slower due to idling the car. If you are using the radio and lights inside the car you could be draining the battery even faster. Which might leave you stranded with a dead battery.
2. Your engine could overheat if your leave your car idling too long. This usually happens if your car has a mechanical problem. If this occurs, take it to a mechanic and have them look over the coolant system or the belt fan.
3. Your car may run out of gas when idling too long. Having an empty gas tank can surprise people when your car is idling because you’re not moving the car.

Common Ways a Car Battery Is Drained

 A lot of things can drain a battery. It’s like a human on a long day at work. There are plenty of things that can drain your battery. A dead battery can be annoying, but it can be avoided. Here is a list of culprits:

1. Leaving your headlights on. This is the most common way to drain your battery. When you are in a hurry you forget to turn them off. The newer cars have an alarm that dings when the car shuts and your headlights are still on to avoid this problem.
2. Electrical draw. Even when the car is off. Your battery still provides power to a few items like the radio, lights, the clock, and the alarm system. When the engine is off the alternator can’t recharge the battery. Therefore, this will drain the battery.
3. Battery connections. It’s important to look at the terminals on your battery to make sure they aren’t corroded.
4. Battery isn’t charging while driving. Your battery’s job is to start the car and the alternator’s job is to charge the battery. Therefore, is the battery isn’t charging then you might need to replace the alternator.
5. Your battery is old and doesn’t hold a charge. Most batteries don’t last forever, so, they will need to be changed at some time. On average most batteries last about four to five years.

When Can You Leave Your Car Running?

Even considering the risks above, there may be some appropriate times to leave your car running. Some examples are:

1. Warming up your car during winter and letting your car only warm up for one to two minutes.
2. When pulling off the road to let an emergency vehicle pass. Turning off the car and starting it again would take more gas to start the car.
3. Lastly, sitting at a stoplight. Even if the light takes a while to change to green. Turning off the car could take longer to start it back up if there are other cars behind you.

How Long Can Your Battery Last While Not Being Driven?

This is the most common question for people, especially when your car is not being driven or you are storing your car for winter. Many different factors play into this decision. It mostly depends on the condition of your battery. If your battery is in good contrition, it can probably last anywhere from two to three weeks without going flat.

What Does Going Flat Mean?

The term going flat, when speaking of your battery, means your vehicle’s battery is drained. The car didn’t have enough time to charge the battery and now the car won’t start. This usually occurs when you have left something on in your car such as the radio or interior lights.

Ways to Prevent a Battery from Going Dead

A battery can go flat for many reasons, the most common culprit is leaving something electrical running for a long period. There are a few things you can do to prevent your battery from going flat. Here is a list of helpful tips:

1. Use your car at least once a week for at least a short 15-minute drive. This helps the alternator add a little bit of charge back to the battery when sitting for a while.
2. Make sure you don’t leave anything plugged into the car when it’s not running. This can mean a dashcam or the radio. These can drain your battery if you’re not starting your car regularly.
3. Make sure you turn your lights off when your car is not running. Most cars nowadays make a noise if your interior or exterior lights are on. When the car is off, the driver will be notified to avoid a dead battery.
4. Lastly, get a trickle charger. A trickle charger is a small tool that can put a small amount of chargeback into your battery when your car is sitting. Just make sure you get the right trickle charger for your car.

How Long Can You Play Music if the Car is Off?

Most car batteries are around 60 AH so they can use 60 Amps for one hour, or six Amps for 10 hours.  A standard car stereo is running off a 10Amp fuse but it will only use half the amps in general use. With this being said, you can use the radio for two hours comfortably and not worry about draining the battery.

However, if you’re stretching the limits I would say a max of five hours. If you use the battery for ten hours without letting the car run, your battery will be completely dead. Then you will not have enough juice to try and start the car again without a jump. 

How Long Can You Leave Your Headlights On?

Considering most batteries are 60 Amps. The headlight fuse on most cars is 10 Amps and trucks are 15 Amp fuses. The weather has something to play into how long the battery will last too.

Obviously, the colder the weather, the more battery it will drain. The battery will be completely drained within four to seven hours. This is considering the battery was fully charged.

Conclusion

As long as you take care of your car in general it will not have too many problems. Taking care of your battery is very important because if your battery isn’t working then your car won’t start. Leaving your car sit for too long can be a negative too.

Letting your car sit for a long period is okay but knowing how to prevent further damage is important.  Hopefully, this article has helped you decide what to do or not to do when debating on how long your car can sit. The myth of idling has been busted too. It’s okay to leave your car idle in moderation.

Get more tips from VehicleFreak with these posts:

Why Does My Car Only Start In Neutral – But Not Park?

How Long Can A Car Idle? Is It Bad For Your Car?

Car Won’t Stay Running Unless Foot Is On Gas