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Is A Car Alarm Connected To The Battery

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The battery of a car has a simple function: to generate enough power to crank the engine of the vehicle when you turn on the ignition. Any other activity it performs outside this when the engine is not running is secondary. Some of these functions include proving power for the light, radio and wiper of the car when the engine is not running. So is a car alarm connected to the battery of a car also? All these and more, we are about to find out in a bit. Please stay tuned!

Is A Car Alarm Connected To The Battery

The alarm system of a car may be connected to the battery of the car, so it can be getting constant power supply directly from the vehicle. However, most car alarm systems have their own independent power supply in form of a backup battery attached to the alarm main module. So if the car battery is cut off, say by a bugler, maybe by clipping the battery cables, the backup battery of the alarm system (which is often hidden) kicks in. This is to make sure that the alarm system always has power to work, never leaving anything to chance.

One of the main issues we have had with people is the impact the car alarm system has on their car battery. Well, the truth is that the alarm system you decide to install in your car will determine if your car battery will drain faster. So for the context of this post, we will be looking at the impact the car alarm system has on your car battery when it is connected to it.


For car owners, there’s nothing as disconcerting as when you wake up in the morning, approach your car after is has been parked through the night to disable the alarm for you to enter the car, but instead of you to get the normal beep-beep sound, you are getting a very slow annoying sound.

To make matters worse, you now try to crank the engine by turning on the ignition but your car battery is completely dead. This problem often happens so we have to be careful how we manage this. First off, let us look at some of the causes of this issue, because knowing the cause will determine how we will treat it.

Alarm staying on

Truth be told, most people leave their alarm system on even when the car is parked or turned off. In fact, for most alarm systems, once you shut down the ignition and lock the car, the alarm automatically kicks in. But for the alarm to stay on, it has to be drawing power from nowhere else but the car battery.

The alarm system is connected to a lead wire from the battery, and since the car is turned off, it means the engine is no longer charging the battery and this will make the battery drain way faster. If this happens for a long time, it will ultimately lead to a dead battery.

Old battery

Every battery has a life span once it is in use – even if it is the rechargeable type. Once your car battery works for about five to six years, it is no longer as efficient as it used to be and cannot hold enough charge as before.

So you will notice that the car alarm system will begin to have a negative impact on your car battery when it starts getting old. The battery loses charge easily when the car is powered off. And when the ignition is turned on, it cannot crank the engine of the car.

However, if the car battery is relatively new, it can last for a good number of days before it goes flat. So the idea is that the longer the number of years your car battery is, the lesser it can hold the car alarm system when the car is turned off, as it’s no longer charging the car battery.

Mode of installation

It is way easier to have custom fitted alarm systems. In that, the alarm system was installed by the manufacturer of the car. So the alarm system is designed in such a way that it integrates into the power system of the car where it would not be a liability to other components of the car, for instance, the car battery.

So this is actually a good thing. However, if the alarm system is an aftermarket one, this could be a potential danger to the battery of the car. If the auto electrician is not careful or professional enough to wire the alarm system in the proper way, this might cause more power drawl on the car battery than is needed, which is rather unnecessary.

Short circuitry

Although this issue is not so common, a short circuit in the wiring of the car alarm system can cause the battery to drain faster. A short circuit happens when an exposed wire touches the body of a metal part of the car, and competes a connection that is not needed.

This causes the power that should be transferred to the alarm system to be transferred to the frame or body of the car in the form of grounding. If this happens for so long, it will cause the battery to drain until it is completely flat.

As a result, you will need to contact your local electrician so that he can check the entire wiring of the system and correct it. If this issue is not put in check, and a new battery is put in the car, after a while, it will die also!


We have taken the time to explain how the alarm system of your car can affect your car battery. But don’t worry. It’s not all doom and gloom. Find below are some of the things to do to make sure you maintain your battery even as it is connected to the alarm system of the car.

  • ü We recommend you get alarm systems with its own back up battery.
  • ü Try to get car alarm systems that automatically turn off the ignition of the car when it is being tampered with, rather than keeps honking. It cuts out the ignition, and it cannot be hot wired, so the thief cannot drive it anywhere. This saves a lot of power as compared to the ones that just make noise once there is suspicious contact with the car.
  • ü We recommend you go for cars that have custom alarm system already installed by the manufacturer of the car rather than aftermarket products. However, if you insist on aftermarket alarm systems, make sure you get the best, and then get a very experienced and qualified auto electrician to do the wiring for you.
  • ü If you have to leave your alarm system on overnight (which is the idea anyway), try to make sure you find a way to charge it sometimes. Plug the battery charger and cycle it on and off for a couple of weeks.
  • ü For like every five to seven days, drive your car through your driveway for about say 20 to 30 minutes. This will help to maintain a charge in the battery when you leave it parked.
  • ü If your alarm system is such that it comes with a backup battery, you can disconnect the negative terminal of your battery, thereby making the alarm system work on its own back up battery.
  • ü If your car alarm system drains your car battery, you might need to jump start the car. So make sure your battery is easily located or accessible because it might come in handy.
  • ü For your car, make sure you know where the jumper leads are, or you know any hardware store where you can get one easily.


Alarm systems are important, but make sure it does not affect the life and efficiency of the car battery. Let this post guide you.