How Door Ajar Switch Car Can Drain Battery

How Door Ajar Switch Car Can Drain Battery? [Explained]

Car battery drains charge for so many reasons. The battery can lose charge even if you leave the doors open. Are you wondering how door ajar switch car can drain battery?

A door ajar switch light draws power from the battery when it is activated. The battery drains faster if the engine is off and the door ajar switch light is on for a long time. There is no other power source for the door light, and it’s designed to draw charge from the car battery.

If you leave the door open for a minute or two, there will be no significant amount of battery drain. Leaving the door open for more than hours will surely impact the charge of the car battery.

How Does The Door Ajar Switch Light Drain Battery: Check Facts

The door ajar light gets activated when any of the doors of the car is not properly closed. When a door ajar light is on or activated, it will draw charge from the car’s battery and will consume power until the doors are properly locked.

Though the power the door ajar switch requires is very little, it can drain a huge amount of charge if the door is not locked for more than hours. It’s even possible to drain the whole charge of the battery because of the door ajar switch light.

Sometimes, the door ajar switch stays on because of any electrical short in the switches. If the light is not stopping blinking even after locking the doors, there may be a problem with the door switches. Conduct a professional car mechanic to find out the exact reason.

How Long Before Car Battery Dies With Door Ajar Switch On: Check Now

This actually depends on the condition of the battery and others. As you know, the amount of charge a door ajar switch light consumes is very little. So, it’s not possible for a door ajar switch light to drain the whole charge of the battery overnight. 

If the battery is fully charged, it may require around 4-5 days to drain the battery completely. If a car’s battery is completely drained because of the door ajar switch light, you need to boost the car through a jumpstart.

To save car owners from these issues, modern cars come with a control that turns off the interior light after the ignition has been off for a while. As the car door ajar is a common issue, this automatic control helps users to save the charge of their car battery.

Probable Reasons For Battery Drainage: Know More Reasons

Door ajar switch consumes battery charge in a very short amount. There are other common reasons that are responsible for draining your battery charge. Check them out.

Loose Battery Connection

Check the connections with the terminal of your battery. If the terminals have loose connections or corrosion, they won’t get recharged properly and will drain charge faster.


Headlights consume a good amount of charge from the battery. If you leave the headlights on, it won’t take much time to drain the charge of your car battery.

Some cars come with an automatically disable feature if idle. Make sure to disable the headlights if your car doesn’t have this feature.

Old Battery

Old car batteries never perform well. It’s recommended to change a car battery every 3 to 4 years. If your battery is draining charge faster than before and it’s an old battery, change it as soon as you can.

Extreme Weather

Car batteries can’t perform as expected in extreme weather. There will be a lack of performance in too cold or on a hot summer day. If you have an older battery, it will drain charge in extreme weather conditions.


How Do You Disable Door Ajar Alarm?

If you left the door open in a car, there would be an alarm for that. This is to remind you to close the door properly. You may disable the door ajar alarm if you intentionally left the door open.

To disable the door ajar alarm, you need to find the alarm key. There will be a button that disables the alarm if something is open or unlocked.

Does Leaving Car Door Open Drain Battery When Car Is Off?

When the car door is open, the only thing that consumes charge is the alarm light for the door ajar. This indicator consumes a very small amount of power. Even if the light consumes power for a couple of hours, the battery will have no problem.

It is important to be aware that leaving the door ajar overnight may drain the battery. If this happens, the battery can be fixed with a jumpstart.

Do Car Battery Control Door Locks?

Well, the car battery doesn’t control door locks. Modern cars are designed to control or lock car doors with a remote.  Though it’s not controlled by the battery, you still need a battery that’s not dead to let the remote work or connect with the car. If your door lock is not working, there may be problems with the key fob.

If the battery is dead and you can’t connect the remote to the battery, you should use the car key then. So, door locks are not controlled by the car battery but need the power to operate.

What Can Drain A Car Battery When The Car Is Off?

There are a few things that drain a car battery when the car is off. The radio will drain the car battery if you play it when the engine is off. A car includes so many indicators for different issues. Whenever the indicators blink, the battery has a tiny draw of charge.

The door lights and interior lights drain a battery if they are activated for hours. The electrical components get charged by the battery, which is why, if they are active, the battery is draining.

Final Thoughts

So, door ajar switch car can drain battery but not instantly. There are so many things that affect the charge of a car battery, and the door ajar switch will be the slowest one. As it’s related to your car’s battery health, you should not ignore the risk of battery drain. 


Hsu, B. (2021, December 3). Why your car door won’t lock or unlock properly. Autoblog. Retrieved February 22, 2023, from

Martin, S. (n.d.). How do you leave your car door open without draining the battery? Jerry. Retrieved February 22, 2023, from

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