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What Can Drain A Car Battery? Here Are 6 Common Reasons To Learn

ByTsukasa Azuma-June 27, 2023

A dead battery means your car won’t start – making the headlights dim and the engine unresponsive. It can be real trouble should it drop dead in the middle of nowhere or in the morning when you are already late for work. What drains a car battery? Are you curious about what the reasons might be?

What Can Drain A Car Battery?

Many of us wonder what causes car battery to drain. Contrary to popular belief, there are quite a few things that can happen that lead to drained batteries even if you are already equipped with the best-rated car batteries. Read on, and learn about the 6 most common reasons that may suck the juice out of your car battery.

What can drain a car battery when the car is off (Photo: mechanicbase.com)

1. Keeping the lights on

Keeping the lights on is one of the reasons what kills a car battery. It’s a mistake that every driver has made at least once in their lifetime as they ask more than one time “what could be draining my car battery”. You have come from work really tired and rushed to the home leaving the headlights on or the trunk open, making the battery drain overnight.

Even the small dome lights can drain the car battery dramatically. Or after packing your car at home, you forget the light so the car battery drains overnight. So, make sure you haven’t left any lights on before closing the door behind you.

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2. Electrical problems

If someone asks you the question “what drains a car battery when the car is off?”. Electrical problems are the answer you should bear in mind. Even if you turn the ignition key off, some functions still keep running. It’s normal for the security alarm, clock, and radio presets to be operational all the time. However, some other components might be switched on if there’s an electrical glitch. For example, the parasitic drain could extend to turning on the trunk and glove box lights, which typically remain off.

3. The battery is in a weak condition

Poor maintenance can leave a battery in a fragile condition, so it may not retain power for a long time and it is what causes a car battery to die quickly. It will be vulnerable to every condition. Even small drains like the clock or the radio’s memory function can leave it dead. Besides, such a battery doesn’t fare well in extremely hot or cold weather. So, take care of it if you don’t want to deal with a dead car in the morning.

Note: Trickle charger is an effective solution for battery maintenance. A trickle charger helps charge a battery slowly and prevents it from overcharging. Therefore, if you need to buy one, here is the list of the best trickle charger products to purchase recommended for you.

4. Corroded or loose battery connections

It’s another consequence of irregular maintenance. Loose or corroded connections won’t let the charging system work properly. It may drain the car battery even when you are driving. Many car models use the alternator to charge radios, clocks, lights, and other small components. In that case, a charging issue can make the draining worse. If the battery doesn’t charge properly, you should have it diagnosed by a professional mechanic.

5. Faulty alternator diode

If its diode is corroded, it will cause the circuit to draw power (Photo: pinterest.com)

Another answer to the question of what drains a car battery is a faulty alternator diode. The alternator does the job of supplying power to a few electrical systems and recharging the battery. If its diode is corroded, it will cause the circuit to draw power even when the engine is not running.

6. Old battery

If the car consistently shows the problem of not starting, the problem might be a worn-out battery. An old battery is the last reason that drains a car battery. Typically, car batteries have a lifespan of 4 to 5 years. So, if you often face the drain car battery trouble, it’s probably time for purchasing a quality battery. Changing a new battery is the right choice for you by going to the trustful garage.

What Drains A New Car Battery?

A normal lifespan of a car battery is about 3 – 4 years. After that, the battery can start wearing out eventually and need to be replaced by a new one. If you have got a new battery for your car but you find out that your battery keeps dying? Here are 3 reasons for it:

1. Driving in too many short distances

If you often drive your car short distances, it could be a reason that drains a car battery. There is no surprise that your battery has a tendency to end too soon. The main function of the car battery is to supply power to the vehicle’s ignition. Driving too many short distances means your alternator doesn’t have enough time to recharge between starting and stopping your vehicle. Gradually, it makes your battery drained and doesn’t last long as it should.

2. Extreme hot and cold weather

If the weather gets too high (above 100 degrees) or drops too low (below 10 degrees Fahrenheit), this will result in a bad impact on your car battery. Leaving your car in these bad temperatures for a long period of time will force a build-up of lead sulfate crystals. The sulfate buildup is one of the main reasons that shortens your battery life and increases the recharged time that your battery needs.

3. Faulty charging system

What drains a car battery could be a faulty charging system. In order to recharge your car battery, the alternator of your vehicle must provide it with energy. If some parts of the system go wrong, it is not surprising that your car battery will be dying too soon.

What Happens If Your Battery Drain?

If you have a drained battery, and you ignore it, the battery will drain to 0 % and dead. So most of the time you can not start the engine. Think about you are driving on the highway, and you have a dead battery. You will be in trouble since everything will be delayed and it affects other drivers too. Or you are about to go to work or date but your engine does not start? What a bad day. So remember to check your car or go to the garage to make sure your car works continuously.

How To Detect Battery Draining

It is frustrating to have a battery that won’t hold a charge, and figuring out what’s causing the problem can be tricky. Given that the cause of the battery drain is not human error, you will need the assistance of a qualified mechanic who can diagnose your car’s electrical problems and determine if it’s a dead battery or something else in the electrical system. Or else, you may also learn these tricks to perform at home.

1. New battery

In case your battery is still new (car batteries have a lifespan of approximately six years), a jumpstart should be all you need to get your hand dirty. This solution comes with jumper cables or a standalone jump started stashed away in the truck. Since the battery is healthy, it’ll receive electricity from the other battery, and then charge up properly.

  1. Parking and turning off the car with a jumpstart next to the dead one. You need to pop both cars’ hoods and get the jumper cables out. You should also protect your hands and eyes in case something goes wrong.
  2. Connect from one end of the red (positive) jumper cable to the red post of the dead battery.
  3. Connect from the other end of the red cable to the red post of the charged battery.
  4. Connect from one end of the black (negative) jumper cable to the black post of the charged battery. And the other end to an unpainted metal part in the dead car away from the battery. This safeguard grounds the circuit to prevent sparking.
  5. Start the car with the charged battery. Let the engine run for 5-10 minutes.
  6. Go ahead and try to start the car with the previously dead battery. If it starts, let it idle for at least 20 minutes when you don’t plan on immediately driving. If you do need to take off right away, drive for at least 5-10 miles to completely charge the battery back up.

Before taking off though, remove the battery cables in the reverse order they were attached. That means the black cable is attached to the metal ground first, and so on.

2. Old battery

A new battery is all you need here. However, it’s best to determine if it’s actually your battery and not something else before spending over $80 on a new one.

There are a few popular signs of a bad battery. One evident sign would be the complete absence of any lights or cranking when you try to turn on the car. Another would be the engine cranking furiously but not actually starting. This one is less clear but happens more times than not, it’s the battery.

It’s easy to jump straight to towing the car to a garage if it won’t start, but you’ll spend less time and money by doing a little self-diagnosis.

Note that you’ll most likely be able to jump a dying battery to get somewhere, but there’s a good chance it won’t begin under its own power if you try it again with the same bad battery (i.e. don’t strain yourself somewhere).

Sometimes the battery can be so damaged that it’s unable to take a charge for a jumpstart, too. The best way to know for sure is by taking your battery somewhere that does free battery testing. Auto parts stores like O’Reilly, Autozone, and Advance Auto Parts will all offer this—then you can buy a new one right there if need be.

Watch the video below to see how to check for and fix a car battery drain in your car:

What You Should Do To Avoid Drained Battery?

  1. First, make sure you turn off all the interior lights and that nothing left is turning on before you leave the car. Same with the radio, you should turn it off if you do not drive. Interior lights and radios when turned on can drain the battery.
  2. Second, keep the battery clean. It is really important and you should do it frequently. Use a dry rag to wipe off any dirt or residue near the terminal and connections areas, An unclear battery can sometimes be the cause of its damage.
  3. Third, remember to check the cable connections to the battery. The connection must be tightened and cleaned. A loose or dirty connection between the cable and the battery can lead to the draining of the battery.
  4. Fourth, use a portable car battery charger or a jumpstart and charge the battery if it is below the performance level. The charger can be found at the automotive store where you can find other things rather than only the charger. Remember to use the charger’s jumper cable to test the wattage of the battery.
  5. Last but not least, taking your car to the garage for annual maintenance will keep you far away from what drains a car battery. The specialist will check and if it needs, they will replace the new battery for you.

Sump Up

As you can see both old and new car batteries can drain if you don’t take care of them in the right way. Hopefully, after reading this article you will get a deep knowledge about most of the reasons that make your car battery keep draining and do know how to handle them. If you have any questions about “what drains a car battery” or any car questions, feel free to leave us a comment in the box below.

Tsukasa Azuma is an awesome car blogger of Car From Japan. He owns a car repair shop at downtown Osaka, and he put all that experience to good use in his sharing posts. Tsukasa’s blog is one of the best resources for information about keeping your favorite imported car running smoothly. Moreover, because of being passionate to learn about the recent happenings in auto industry, he doesn’t only provide great car maintenance tips, he also always updates latest trends in among car brands and share them in his own interesting viewpoint.

Comments

vbucks codes10:23 August 09, 2019
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I was looking for an article which could provide me proper guidance required to prolong the lifespan of the battery. You mentioned that our battery might have a tendency to end too soon if we drive our car in short distances. This is great to know, especially because my car died the other day when going to work. I’ll look into finding an auto service near me that can help me get to the bottom of this. I wonder if this has to go back to my AC and how it isn’t working.

Vbucks Freei04:35 August 06, 2019
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My car battery died a few days ago and i bought new one but the same battery died again lol
cost me a lot

Mut Gen15:37 August 01, 2019
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I was stuck one day in the middle of the road due to flat or drained battery. Your post helps to explain a few of the mysteries that i was experincing

Thomas Jameson23:12 July 25, 2019
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It’s good to know that keeping any lights on in your car can drain the battery dramatically. My wife has a really bad habit of leaving the dome lights on at night when she gets out of the car. I’ll pass this information along to her so that she can avoid keeping them on and draining her battery.

vbucks codes19:05 July 09, 2019
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I was looking for an article which could provide me proper guidance required to prolong the lifespan of the battery.

robux codes18:59 July 09, 2019
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Recently, we have gone the garage to leave and found the battery drained to the point where to car would not start.

Kate Welling08:07 May 29, 2019
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You mentioned that our battery might have a tendency to end too soon if we drive our car in short distances. This is great to know, especially because my car died the other day when going to work. I’ll look into finding an auto service near me that can help me get to the bottom of this. I wonder if this has to go back to my AC and how it isn’t working.

yandex mail not working15:42 April 16, 2019
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A battery is the essential part of the electronic device so it is very important to have proper information about the battery so that you will be able to choose the correct one and able to properly care your device battery so that it will give long life service.

Caden Dahl13:48 January 17, 2019
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Knowing what can drain your battery is important. I think mine might be having some problems. I’ll probably get it replaced soon since I don’t want to be stranded.

Jim Stinson09:39 December 15, 2018
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I seem to have a somewhat unusual problem with my battery. We have for several years left the keys in the ignition when it is parked in the garage which is locked. Recently, we have gone the garage to leave and found the battery drained to the point where to car would not start. Through trial and error, we found that if we remove the keys from the ignition, we don’t seem to have a problem. Is it possible the the ignition switch could have a fault that could cause a drain just by having the keys left in the switch?

Loretta A Salazar08:23 December 10, 2018
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Will a new battery get rid of the glitches?

Loretta A Salazar08:21 December 10, 2018
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Who fixes electrical glitches? Is it done with a computer?

Loretta A Salazar08:10 December 10, 2018
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Why do dome lights stay on longer than necessary and drain the battery? My car is old, a 94 Chevy Caprice. Does battery have anything to do with not turning off the dome lights?

Loretta A Salazar08:13 December 10, 2018
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When do I get a reply?

Yvette07:23 November 10, 2018
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have a 2015 VW jettta. the battery has died at least 5 times in the past month. took it to the dealer and after 8 hours, they said it was the radio. gave new radio and still died. dealer had for the past two weeks and just told me that now it’s the driver side door motor. does that even makes sense? i’m thinking it’s something electrical but not sure.

help…i am frustrated.

Thank you!

Emily Fox19:08 October 25, 2018
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Battery is an expensive component of the vehicle which is responsible to store and distribute electrical energy generated by the alternator. So, such component needs regular maintenance to enhance its lifespan. I was looking for an article which could provide me proper guidance required to prolong the lifespan of the battery. The battery is comprises different types of chemicals which is influenced by the environmental fluctuation. So, suitable initiatives needs to be taken to protect the battery from such kinds of fluctuation.

Zoe Page20:26 October 15, 2018
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Information given in this article about the factors responsible for drainage of the battery would be very helpful for newbies. Undoubtedly, the temperature is an important factor responsible for the drainage of the battery. Hence, the battery should be properly insulated to prevent any kinds of major impact. Apart from this, the older battery couldn’t effectively store electrical energy in the vehicle which impacts the performance of the vehicle in a very adverse way. So, the condition of the battery needs to be inspected at a regular interval and older battery should be replaced with suitable substitutes to ensure continuous power supply to the vehicle.

Derek Dewitt22:04 August 17, 2018
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My car battery just died the other day, but I’m not sure what caused it. I had no idea that temperature played such a huge role in the lifespan on your battery. I will have to avoid letting the new battery heat up and get too cold in the winter.

Bradley Berger06:38 August 15, 2018
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Why do cars still allow accessories to work such as a radio without the engine on if this can cause the battery to drain and not restart.