By Erik Watkins

Why Does My Car Battery Keep Dying and Alternator Are good?

Last updated: May 16, 2023
Why Does My Car Battery Keep Dying

In the ignition process, the battery plays a key role. It provides the initial power to jump the engine. Your vehicle then relies on the electromagnetic alternator to perform mechanical movement and other interior operations.

In most cases, charging the battery requires no manual intervention. A reverse reaction called recharging takes place to transmit power back to the battery.

Though we only mentioned two parts in the process above, eight factors are at play, more or less contributing to the issue. This article covers all aspects of this problem, including detailed causes and some helpful solutions. Check it out!

Why Does My Car Battery Keep Dying? 

There are three main aspects to blame: user negligence, issues from the electrical system, and the battery itself. There is no shortage regarding the causes of a dead car battery. Instead, this article should focus on the most common triggers out there.

However, we mean that your car does not start after stopping for a while when it comes to this situation. If the car battery dies randomly when you are in traffic, the charging system may suffer from error. 

Why does my car battery keep draining? Stay tuned for the following parts. We have got your back

1. Leaving Headlight Overnight

One of the battery functions is to power the onboard electronics, including headlights, dome lights, etc. Note that it still works when the engine is off. This means that excessive performance of these accessories possibly drains the battery.

The headlights become the never-ending culprit when the number of times you turn them on reaches a limit. This situation includes seemingly innocuous activities in a short time, such as going to the grocery store or takeaway coffee shops. 

Meanwhile, leaving the dome lights on overnight is sure to kill a weak battery. Hence, you should check these parts in the dark to recognize the signs with ease and accuracy.

Some latest models now offer automatic shut-off within about half an hour after removing the key. If this function works well, it takes a load off your mind. However, checking later to ensure the lights go out on time is a piece of good advice. Once you get back and everything remains unchanged, you have a firm basis to confirm the cause for this problem.

2. Weak Battery

Some people prefer to go straight to root research – check the battery as soon as a fault occurs. Of course, there is no right or wrong. Maintenance definitely entails quite a few problems if you do it right. Luckily, this process does not require complicated techniques to complete at home.

A general rule of thumb is that the cell should be filled with electrolytes. Every time you look inside and notice that electrolyte levels are far from the top of the lead plates, it is time to act. 

However, the right approach determines the outcome. Improper access reduces the charging capacity of this unit. Depending on the water quality in your area, straight into the faucet is allowed. On the other hand, you should use distilled water and top off the cell.

The hydrometer may come in handy if you do not enjoy complicated assembly steps. This tool works on the weight of the remaining electrolyte. The lower the result, the closer your battery reaches its failure stage.

Another effective measure is the load tester. Despite the slightly expensive cost, it is worth your investment. This device simulates start-up and reports on both load and unloads voltages.

Make sure you accumulate enough skills for this job not to degrade its performance. Finally, some stores offer this service for free or a modest fee. It is always the best way for the inexperienced.

Important note: An unqualified battery may cause an explosion when exposed to the right conditions. Remember to wear protective gear when you perform the inspection and maintenance on your own.

3. Poor Battery Connections

Poor Battery Connections

This unfortunate situation can happen to battery terminals, connectors, and, most commonly, battery cables. No matter the parts, it consists of two states: loose or corroded. Both interfere with electricity transmission, thereby preventing the battery connection of the charging system.

You may notice small bumps when driving on uneven terrain in the first case. Some kind of crash or strong vibration may have caused this. On the right side, it is not hard to solve with some basic tools. If possible, keep your eyes on the connections of the ground cable to the starter, fuse box, frame, etc.

Corrosion is a worse situation caused by overcharging or releasing certain compounds from the battery fluid. Its consequences are flashing lights, engine stoppage, or damaged components. Anyway, things are still under control. 

You can easily spot the manifestations of this phenomenon through visual observation. The large multicolored blooms are among the most visible. So how to deal with it?

A stiff bristle brush, baking soda, and water should stay on your checklist. Then proceed as usual cleaning. An important note is not to let the baking soda mixture seep inside the battery. Also, you might want to keep the mixture away from the garage floor or the driveway or clean the stains as soon as possible if any. The corrosion, combined with baking soda, leaves the most stubborn residues. Your driveway and garage floor can become messy, and of course, no one wants that. 

For battery terminals and cable connectors, we recommend sandpaper or a special tool in the form of a wire brush. They easily reach tight spaces and promise a clean and polished surface. As a result, the battery connection becomes better than at first.

See more: How To Clean Battery Corrosion

4. Parasitic Drain

There is a form of invisible power drain that kills your battery over and over again. In simple terms, it refers to parts of the electrical system that still function even when you are not behind the wheel. Parasitic drain reminisces of a headlamp or dome situation but is hard to test.

Checking the current in your car with battery disconnection is the only way to find out. Almost every home mechanic prefers a multimeter for this purpose. A helpful tip is to set the highest amperage to protect the internal fuse. If you do not have much experience, choose an induction clamp instead. This meter gives the required result without power cut-off.

A few take advantage of the inspection light to find the drain. However, it only yields a relative result for reference as the measurement is less precise. When the light turns on, you only get the sign of this problem, not the details. On the bright side, its usage does not require a complicated setup. The process starts by disconnecting and looping the circuit between the battery negative terminal and the ground.

Regardless of your tool, gradual elimination brings you closer to revelation. It would help if you tried with each fuse individually until no more drain can be found. Then follow the corresponding circuit and get to the specific components. That’s how you find the harmful parts.

In most cases, the trunk, glove box, and other interior lights make up most of the cause. They drain the battery without your attention.

Here’s Why Your Car Battery Keeps Draining

5. Charging Issues

If you often suffer from steering and battery problems at the same time, the charging system has sent out an emergency signal. This unit takes over the task of power supply after the engine jump. 

Service Battery Charging System Warning

Luckily, you need to keep an eye on one part only – the alternator belt. In good condition, it should be tight and free of cracks. When you notice any contradiction, the belt has prevented the electricity generation needed for operation.

Tighten it to fix your problem. If it is equipped with an automatic tensioner, you probably need a new one. The same situation recurs with the belt itself once it shows signs of aging.

6. Broken Alternator

As noted above, the main responsibility of the alternator is to power your car when the engine is on. Additionally, it recharges the battery with mechanical energy.

You get in trouble when a faulty diode fails to get the job done. Its substandard performance results in subpar operation or failure of other electrical components such as lights, AC, entertainment systems, etc. In the worst scenario, the bad alternator faces damage if idling keeps things steady until getting on the road.

Whatever the case, you must carefully examine the alternator output to get the correct diagnosis. A multimeter with a touch clamp is sure to be a great aid in this mission. 

However, it can only give preliminary results. A thorough inspection is not complete without specialized tools, electrical expertise, and model-specific knowledge. For instance, leaving the battery connected and the engine running during examination makes the damage more serious.

We recommend seeing a professional mechanic get the most thorough diagnosis. It is good news that some service providers do not charge a fee. Remember that simple and comprehensive tests lead to different results. Needless to say, good preparation always comes with great things.

When you get professional help, it simply means repairing or replacing a brand new one. As a result, a charging system becomes more stable. Sad to say, the power system may be suddenly cut off due to other serious damages in some rare cases.

7. Too Much Short Trips

What actually happens if my car keeps dying battery and alternator are good? Probably something is wrong with your charging mechanism. The battery stays steady as it enters the recharge phase each time the engine runs. In other words, it regenerates energy every time you drive. 

The short operating times are not able to meet the power requirement. Worse, they reduce the battery lifespan indirectly after many accumulations. If you have repeated this careless action and found no technical errors above, changes are short travels that kill your battery.

Save our note for the next time. At least this situation has taught you a good lesson. Let your vehicle make a long trip every 1-2 weeks.

8. Extreme Weather Conditions

You can turn a blind eye to this section if you have a new battery. However, the old and weak ones are strongly influenced by the weather, especially the temperature.

In general, extreme conditions reduce charging capacity. Significant temperature differences often produce sulfate crystals. They enter the inside and wreak havoc on the structure. Specifically, harsh dog days may deform this part. Meanwhile, cold weather deteriorates productivity.

Some people do not pay much attention to this aspect as these harmful situations always happen in silence. In fact, the battery and even your vehicle cannot stand the test of time.

Limiting exposure to serve conditions to increase its cycle as much as possible. For example, it is best to park in the garage or the shade in the summer. Try to operate the engine regularly in winter, so the battery is fully recharged.

Signs Of Batteries About To Die
Signs Of Batteries About To Die

See more: 8 Signs Your Car Battery Is Dying

How To Avoid Car Battery Keeps Dying

Any part indeed comes with an expiration date, but the longer, the better. Therefore, maintaining good conditions and working order plays an important role. Even if you find the culprit and rule it out completely, each time still shortens your battery life. Keep in mind that preparation is always better than repair. 

Do the inspection on time, especially in winter. Make sure the connections are tight and free of corrosion. Keep electrolytes at recommended levels and integrity in cells. Routine maintenance helps you detect potential problems early. Handling them as soon as possible prolongs the lifespan of your battery and prevents severe chain reactions to other parts.

Manufacturers also recommend running the engine at least 100 miles or a few times weekly. Limit short trips and idling to a minimum level. If you cannot avoid these undesirable situations, a trickle or tender charger comes in handy. It is usually under the hood with a plug hanging at the front of the vehicle. You can plug this end into a household electrical outlet and refill the battery.


How Long Does A Car Sit Before The Battery Drains?

About four weeks to two months is a fair period for your battery. Even if your vehicle stops in the garage, the energy still connects to the radio, dashboard, Bluetooth, etc. As mentioned above, this phenomenon is called a parasitic drain. Another factor involved in this process is weather conditions. The more inclement it gets, the faster the battery dies.

Removing the battery from your car is the best idea should you plan on taking a long vacation. Remember to store it in a cool and dry place, preferably in a dedicated container. This helps extend its lifespan from about six weeks to six months.

See more: How Long Does A Car Battery Last

Does Bluetooth Or GPS Cause Car Battery Randomly Died?

Most cars today are equipped with entertainment and utility features such as GPS tracker, Bluetooth, etc. Undeniably, they improve the user experience but also create a lot of worries about the electrical system.

In fact, the listed parts do not consume much power, even less than 1W. This equals a minor impact on your battery. However, they can join hands in the battery drain if your car stops too long.

See more: What To Do When Car Battery Dies?


We hope this article has pointed straight to the root of the car battery keeps dying. Besides, the included measures can help to deal with it or at least guide you on the right path.

While there is not much you can do to prevent some bad scenarios, it is not hard to deal with them immediately. However, the more the battery drains, the quicker it will damage completely. That’s why maintenance is always the all-time perfect solution.

Automotive Mechanic at PowerAll

With 7 years experience in management positions leading automotive mechanics at PowerAll, Erik Watkins wishes to share useful knowledge and information about automotive mechanical equipment.


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