What can drain a car battery when its off?

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Have you ever wondered what can drain a car battery when the car is off? Or You car battery keeps dying overnight? Or You get ready to attend to your day’s activities, get into your car to drive off, but then the most frustrating thing happens. It does not start! Well, like you, this is a pestering question amongst many motorists who’ve had to deal with this frustration at the least expected times.

Don’t get me wrong; if this is the first time your car battery has drained when the car is off, you might not need to fret as much. At least not as yet! But, if the battery has drained a couple of times while your car is off, then you must be sure that something is awfully wrong, right?

Well, you are right; having a dead battery repeatedly is not normal. Ideally, what should happen is, when you start your car, the car battery should fire the engine to life.

And Once this happens, the alternator should then kick in and begin charging your battery to full charge while you drive. Therefore, when you park and turn off your car, your battery should be fully charged and ready to start your engine the next time.

How then can your fully charged battery drain while the car is off such that it can’t start your car? Below are seven reasons that might be the cause of your current car battery frustrations:

Car Battery Drain Test  

1. Old Battery

How long ago was it when you last replaced your car battery? If you have been using it for over four years, then the most probable cause of your car battery draining when the car is off is old age. It can no longer hold a full charge like it used to. Typically, you should replace your car battery between every 3 to 5 years of usage.

A well maintained and high-quality battery can effectively serve your car for up to a maximum of 5 or slightly more years. A poorly maintained one, however, may need replacing in as little as 3 years of usage.

Therefore, your constant car battery drains may be a tell-tale sign that your battery has reached its maximum years of service. Replacing it should resolve the car battery draining issue.

Pro tip:If you have, a free maintenance battery, then the charge indicator should confirm to you whether you need to replace the battery or not. A yellow eye is an indication for a battery that needs replacement.

2. Corroded Alternator Diode

If your battery is not old, but it still drains when the car is off, you should inspect the state of your alternator.

The alternator is responsible for recharging the car battery and powering electrical systems of the car such as the radio, lights, ignition, etc. A corroded or defective alternator diode will faultily continue charging the circuit even when the car off. This, in turn, will drain your car battery and cause the car not to start.

3. Electrical Glitches

Electrical glitches in your car and car battery may be caused by factors such as poor installation, faulty fuses, and flawed wiring. These electrical glitches can result in the normal and expected parasitic drains on your car battery becoming excessive and drain the battery when the car is off.

The normal parasitic drains refer to the energy supplied by your car battery to certain components in your car to keep them running even after you turn off your car. These components include your security alarm, radio presets, and clock. However, when your car battery has electrical problems, these normal parasitic drains can be extended to other car components that normally remain off, such as turning the glove box lights on. And this is how your car battery ends up getting drained when the car is off.

4. Ineffective Charging System

When your charging system is not charging your battery as it should, the consequences are a drained battery when the car is off or even worse your car battery draining while you are driving to the point that the battery dies suddenly.

An ineffective charging system can result from either loose connections or corroded tensioners. This, therefore, means that your car battery is not charging properly as it should, and its output is below the expected 13.5 to 14.5 volts. Now, picture a battery that is already not well charged powering the parasitic car components that must remain running when the car is off. Won’t your battery end up drained and dead eventually?

5. Poor Maintenance

Failing to ensure that your car battery is clean and well maintained could be the reason behind the battery draining when the car is off. If a layer of acid or dirt accumulates around the top of a car battery and is not taken care of, the battery can begin to leak its charge. These leaks can continuously grow to the extent of causing massive drains that leave the battery with a little charge that is unable to power the engine effectively.

Car Battery Drain Preventer 

Pro tip: If you suspect your battery is leaking its charge. You can clean it by mixing about 250ml of warm water with a tablespoon of baking soda then dipping a rag into the mix and wiping the battery. If need be, you can also use a soft brush to scrub the battery with the mix. Be extra careful if your battery has removable caps and ensure the cleaning solution does not seep into the battery, as this could damage your battery.

6. Extreme Temperature Changes

In the case of car batteries, extreme temperature changes refer to temperatures above 100 degrees Fahrenheit and below 10 degrees. Leaving your car in such severe weather conditions for long when it is off will result in a build-up of lead sulfate crystals. This build-up will cause any charge in your battery to be drained and increase the amount of time the dead battery will require to recharge.

The lead sulfate build-up is also responsible for damaging your car battery as well as reducing its life span.

7. Driver’s Error

If you can remember, we mentioned in the beginning that if your battery just drained on you for the first time, you don’t need to worry. Here is why. A majority of times, realizing that your car battery is dead after your car has been off overnight or off for a number of hours may make you think that there could be a big underlying issue that caused your battery to drain. Right? But sometimes the case isn’t so. It could just be a costly consequence from a rookie driver mistake you made. Some of these mistakes include:

• You left your headlights on after you turned your car off.

   • You forgot to fully close a car door or your trunk’s lid thus leaving an interior light on the entire time your car was parked.

   • You left an electronic item such as a cell phone plugged in and operating after you shut off your car

My car battery won’t start my car, what should I do?

Well, now that you clearly understand what can drain a car battery when the car is off, it is important to contact a qualified mechanic to have a look at your car battery and properly diagnose the cause of your dead battery.

Preventive Measure to Avoid A Car Battery Draining When The Car is Off

Once your car battery issues have been resolved, you should take the following preventive measures to avoid a repeat of the same frustrating dead battery issue.

1.  • Train yourself to take time when shutting your car off to ensure everything is as it should be. Turn off all lights, close all doors properly, disconnect any electronic devices, and do not leave your radio playing.

•  • Constantly check on the cables connecting to your battery. Make sure they are tight enough to reduce the occurrence of a faulty charging system for your battery. You can also regularly test your charging system using the following steps:

•  • Clean the negative and positive cables to your battery and ensure they are tightly connected.
•  • Get a voltmeter and set it to 20v on the DC scale.
•  • Have someone start your engine and keep it running at 2000rpm.
•  • Connect the voltmeter leads across the battery posts and note your meter readings, which should be a steady reading of between 13.5v and 14.5v. You can also consult the repair manual for your car model to get better information on the expected performance of your charging system.

A reading below 13.5v or one that fluctuates is an indication of a defective alternator, loose wiring or faulty voltage regulator that needs to be promptly addressed by a mechanic.

•  • Occasionally clean your battery. This will allow you to minimize corrosion on your battery as well as identify components that need replacement as early as possible before they cause large charge leaks in your battery.

•  • Service your car and the battery at regular intervals to allow a professional mechanic to detect any battery issues that you are not equipped to notice in their early stages and have them resolved promptly.

There You Have It!

Equipped with this knowledge, you should be able to effectively prevent your car battery from draining when your car is off again. And should it happen again, you should be able to pinpoint the probable cause even before a professional mechanic makes the diagnosis. visit out local battery store near me for any battery need today. 

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