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9 Reasons your car battery keeps dying but alternator is good

car battery keeps dying but alternator is good

When a car’s battery keeps dying, it is usually an indication that the alternator may be bad. Then what else could be wrong when a car battery keeps dying but alternator is good? Many car batteries seem to die after several years, despite the alternator in the vehicle being quite good, and thus there are a few common causes for this.

The battery could have been damaged by overcharging due to a bad alternator or faulty voltage regulator. It may also have been damaged by running in temperatures that were colder than it was made for. An owner has no choice but to replace the car battery when this happens.

What is alternator in car?

car battery keeps dying but alternator is good

The battery dies but alternator is good.  A car alternator is an essential part of the car’s electricity system. If a car alternator does not work well, it will drain the battery and even cause a dead battery. If the alternator fails to work, the battery discharges more quickly than with a healthy alternator. Better do the battery check to avoid any such fault and trouble situations.

What most people don’t know is that the idea of the battery and the alternator are not the same, even though they are sometimes referred to interchangeably. The difference between them is that the battery is in charge of starting your car and keeping it charged while you drive, while the alternator is in charge of powering your car while you’re driving.

If there was something wrong with your alternator but your battery was okay, you wouldn’t be able to start your car, let alone keep it charged, but if any issue arose with your car’s electrical system and your battery died but you had a good alternator, you could still drive.

Also, the alternator on a car is responsible for keeping the battery charged, and therefore the alternator must be working properly. The battery supplies juice to the electrical components of your car, so if the alternator isn’t charging the battery, then you could say that the alternator is malfunctioning.

9 Reasons your battery keep dying

There are a number of reasons your car battery keeps dying even when your alternator is in good condition. Here are the most common:

1. Battery in bad condition

If your car battery keeps dying, it could be because the battery itself is in bad condition. The working order is not in good condition. This can happen for any number of reasons, including:

Overcharging: If you leave your headlights on for too long, the battery will overcharge and the output will eventually die. This can also happen if you leave your car lights on for extended periods of time when it’s not running, or if you leave a charger connected to the battery.

Excessive discharge: If you use your car frequently, particularly in hot weather and at high speeds, it will discharge its energy more quickly than normal. This is why older cars are more likely to have problems with their batteries than newer ones as they get used up faster.

Physical damage: Sometimes, driving on rough roads can cause physical damage to a car’s battery or electrical system that prevents it from holding a charge as well as it should. Better apply a tensioner, a tool that uses force to develop or keep tension.

2. Headlights or dome lights left on

Your headlights or dome lights left on can be a major drain on your battery. Even if you have automatic headlights, you really shouldn’t leave them on for long periods of time. If your car is parked for an extended period of time, make sure to turn off the headlights and dome light before leaving it unattended.

3. Corroded battery

Corroded battery is a common cause of car batteries dying. If you have a car that’s more than three years old, then it’s probably time to check the battery connections. Corroded terminals can cause your battery to drain faster than it should, which means you’ll need to replace your battery sooner than you’d like.

If you notice that your battery is dying frequently, try cleaning the connections with a wire brush and reconnecting them before giving up on them completely. In many cases, cleaning the connection will allow the battery to work normally again.

4. Loose battery connections

If your car keeps dying, the first thing you should check is the connection between the battery and the car’s electrical system. If it’s loose, it might not be getting enough power from the battery to get you started.

Check all of your connections for corrosion or other damage and clean them off with a wire brush if needed. If there’s still a problem after that, it may be time to get a new battery altogether.

5. Extremely hot or cold temperatures

Extremely hot or cold temperatures can cause your car battery to die. If your car is parked in the sun, the heat can damage your battery and cause it to not work properly. The same goes for extremely cold temperatures, where the cold can freeze the battery.

If you think that may be there with your vehicle’s battery, take it to a mechanic and have them check out the problem for you. They will provide a guide and also give an inspection of your battery life.

6. Old battery

The most common reason your car battery keeps dying is that it’s old. Old batteries can’t hold a charge and they don’t always work properly. If you notice that your car battery keeps dying or that you have to replace it more often than usual, then it’s probably because your battery is old.

Your car battery is like a human heart and it needs a good supply of fresh blood (or electrolyte) to keep working well. If the electrolyte gets low or dirty, then you’ll need to replace your battery.

But if you do this too frequently, then it’s probably because there’s something wrong with your battery that needs fixing, not just because it’s old.

7. Accidental Discharge

One of the most common reasons your car battery keeps dying is because you accidentally discharge it. This can happen when you leave a light or radio on in your car, or when you’ve got a faulty alternator.

The first sign of an accidental discharge is that the battery will start to lose its charge, so if you’re not sure whether or not this has happened to you, check your car’s battery to see if it’s losing its charge.

8. Too Many Short Trips

If you’re constantly making short trips, it’s likely that your car battery is dying. If you drive around the block to get a few groceries or go to a store for a quick errand, this will put more strain on your battery than if you were driving around town for a few hours.

This is because when you start your car, it has to work extra hard to turn over all of the components in order for your vehicle to function. This includes spinning up the engine and turning on all of the lights and other electrical systems in your vehicle.

But if you make short trips, these systems don’t have time to cool down between uses, which means they are always working at full capacity during their limited time on use. It’s like trying to run an appliance at its highest setting all day long.

9. Failing Battery

The most common reason your car battery keeps dying is a failing battery. This can be caused by a variety of factors, including:

Age: The average lifespan of a car battery is anywhere from three to five years. The more frequently you drive and use your car, the faster the battery will drain.

Extreme temperatures: If your car has been sitting in the sun or cold weather for an extended period of time, it can cause your battery to drain.

Undercharging: If you are not getting enough charge out of your battery, it may start dying sooner than expected.

The car battery keeps dying but alternator is good?

car battery keeps dying but alternator is good

When your car battery keeps dying but the alternator is good, then you may have two problems going on at the same time. The first problem is that the battery is bad and the second problem is that the temperature sensor in your thermostat housing could also be bad.

Also, it could be a result of a problem in the electrical system. An electrical problem can cause a lot of different symptoms, but one of them would be a car that keeps dying when you go to start it up. You need to figure out if it needs a new alternator or if there’s a short circuit in the wiring somewhere.

In addition, the problem could be low voltage. The voltage regulator on your alternator may not be set to supply enough juice to keep your stereo, lights, and auxiliary circuits running properly.

Therefore, before you jump to getting a new battery or alternator, you should try resetting the regulator and if nothing works, then you might have to end up getting a new battery or alternator.

How does an alternator charge a battery?

An alternator charges a car’s battery when the engine is running. The alternator has two jobs, either of which can take place at any time but not both at the same time. The first job is to maintain the charge in the battery. This happens automatically and is called “regenerative charging.”

While driving and the battery gets low, you will hear an annoying clicking or tapping sound. The alternator is doing its job regenerating a charge into the battery by “dumping” its excess energy back into the car’s electrical system.

Also, it converts mechanical energy into electrical energy while rotating. The amperage, an electric current produced by an alternator, can power electrical equipment such as lights, radios, and other devices in the car.

When the engine is running, the alternator generates currents of varying frequency and intensity as it spins at high speeds. A regulator controls the rate of charge to ensure that the battery receives as much current as it can safely take.

How to wire an alternator to charge a battery?

You can wire an alternator to charge a battery by choosing the right wires, making sure you configure everything correctly and making sure you know where to put your new alternator so that the battery will be charged.

Also, Wire size is important, and not following the correct gauge may cause you to wire too large of a wire which can cause heat issues, or too small of a wire resulting in poor performance.

To charge a dead battery using an alternator in an automobile, charging cables must be connected to the negative and positive terminals of the battery. Build a simple circuit using a car battery, a light bulb, and an ammeter to test the voltage and current produced by your alternator.

You need to ensure that the positive terminal of the alternator is on the positive terminal of the battery and the same for the negative. Once you are sure of the wiring, then you can go ahead to start the engine and keep it running. That way, the battery will get revived.

Importance of battery charging system

The battery charging system on your car exists to preserve and take care of the battery, and to make certain that it is always ready when you need it.

It’s a very simple system – a device that hooks into the battery and regulates its charging. A malfunction of this device will cause problems with your car, so it’s important to understand how it works.

In other words, it is an automobile engine starting electrical system circuit, which can be used to charge a storage battery of the automobile and an electronic control unit.

That is, it is used to supply electric power for the operation of all auxiliary devices in the vehicle that are not run directly by the engine, such as controls, audio systems, and lights. Also, the battery charging system avoids the common problem of leaving a car unused for an extended period.

Such an action can damage the battery and prevent it from properly starting your vehicle. So, a battery charging system recharges your battery once the engine is turned off. It helps maintain an optimum charge level, prolongs its life, and ensures that your car starts when you turn the key.

Car battery keeps dying overnight – Things to check

Do you have a car battery that dies out overnight? You need to figure out why and fix it before it gets worse. First of all, make sure that you do not leave any lights on overnight. The next step is to check your audio system and see if you might have left any equipment on overnight, like a loud and heavy subwoofer. Usually, heavy appliances fry the batter until it stays dead all night long.

A dead battery can be annoying. Whether it’s a faulty alternator, a bad connection, an undercharged battery, or an issue with the power accessories in your car, the GOOLOO Jump Starter 1200A Peak Car Starter is here to give you a jumpstart.

A dead car battery can mean being late for work or appointments, but you have got no more worries with this device. This set comes with everything you need for quick and easy car battery charging and jump starts.

The car battery keeps dying after a few days

Probably the most common symptom of a car’s battery running down is when the car will not start after sitting for a day or two. The first thing to check for a battery that won’t start the car is the battery charge.

The most common reason for a battery running down is that it needs charging. The battery may appear to be fully charged but, in fact, just needs topping up due to the self-discharge rate of the car batteries. However, if your battery fails to retain its charges after days of charging it, you might want to run a check on the condition of the battery.

Also, if it turns out that the battery is in good condition, you might want to check the alternator. Either way, you should always get the car to a mechanic to help you through the whole process.

Why does my car battery keep draining?

How does an alternator charge a battery

Understanding why your battery keeps draining and what you can do to prevent it is the first step in maintaining a healthy battery. There are a potential number of reasons why your car battery is discharging.

Your vehicle’s starter may require service, an alternator or power steering pump may need replacement, or the vehicle may have an electrical short somewhere that is continuously draining its battery down. If you have tried all you can on your own and it all proved abortive, you should visit the mechanic workshop.

Your mechanic will run a check on the battery to know if it is still good or not and also check some other aspects or areas to find out the main cause or reason for discharge. 

Car battery draining overnight – What can you do?

Leaving your lights on causes the most common no start or battery draining problem. Believe it or not, your car can run for a long time with an electrical drain of only 20ma. At a national average load of 5 amps and 12 volts, this 20ma decrease in a draw wouldn’t even turn a single interior light bulb on.

The biggest drain of energy is caused by something you probably think is off or unplugged. You should always check the lights in your car before you go to bed. I once made the mistake of leaving my car boot half-closed and it affected the charge in my battery the following morning.

Therefore, you should always check and confirm you do not leave any lights on in the car. Aside from that, if your battery continues to drain, you might want to get a new one because it is a sign that the battery is bad and can’t retain electrical charges.

How do I know if my alternator is draining my battery?

How does an alternator charge a battery

The easy way to tell if your alternator is draining your battery is to check the battery electrolyte level. A typical car will not experience battery drainage overnight with an alternator that works properly. If no lights stay on after the car is turned off, there will be little to no battery drainage during this period.

The alternator works by keeping your car’s electrical system in balance. Most vehicles built today have an internal monitoring system, called the Battery Management System (BMS), that measures the voltage of the battery as it is being charged and maintains a certain level. If you check your vehicle’s service manual, you will find out what that level should be for your specific car or truck.

So, with a voltmeter, you can check the condition of the alternator to know if it is definitely in good condition to charge and keep your battery active. If anything is wrong in your reading, it is an indication that the alternator is bad.

The car battery keeps dying when not in use

A car battery dies when you are not using the car because it is not being charged by the alternator. To prevent this, keep a trickle charger connected to the battery when it is not in use. If you need to jump-start your car now and then, check the alternator belt for wear and tear, because if that belt loosens up, then the alternator cannot generate enough energy to keep your battery charged.

New car battery keeps dying

Have you recently changed your car battery and started to notice that it keeps dying after a few days? The module is the most likely culprit. The module contains the voltage regulator, overcharge protection circuit, and other electronics that control the charging system.

As long as you are sure you got a quality battery, you might want to check the module to check out some things that could go wrong and provide the best solution.

How do you stop a car battery from draining when not in use?

A car battery runs as an electric current runs through it. As the battery becomes weak, this process is harder on the car’s alternator. Your battery will continually lose its charge and need to be recharged. Fortunately, there are three main ways that you can stop your car battery from draining when not in use.

The best way is to never allow it to drain entirely as this can lead to permanent damage to the battery and your vehicle’s electrical system. You can do that by disconnecting the battery whenever you are leaving the car for days or months.

How long can a car battery sit unused?

A car battery can be stored for about four months if it is not more than 50% discharged and its terminals are protected from corrosion. A fully charged battery should deliver enough electricity to turn the engine over at least three or four times.

Can a bad ground drain a battery?

Yes, a bad ground connection can kill your battery. The first thing to check when your battery is drained or dead is bad ground. A badly corroded connector on a battery cable can act as an antenna, channelling electrical current away from the battery itself and allowing it to flow to places it’s not supposed to.

It lies in this case against the engine block, where it can kill the starter motor or stator or even the battery itself over time.

Can a blown fuse drain car battery?

Yes, a blown fuse can drain your car battery. It’s an unlikely occurrence, but a blown fuse can cause problems with other electrical systems in your car, causing them to drain the same battery that powers your starter.

A blown fuse can also cause both the engine and electrical systems in your car to stop working. The main cause of a blown fuse is a damaged wire or high wiring that is used to transmit electricity.

The symptoms of a blown fuse are when lights stop lighting up, the engine turns off while driving and you are unable to turn on the radio or heat/air conditioning. To fix this problem, simply replace the fuse with another one and turn on the ignition.

How long does it take for a bad alternator to drain a battery?

It can take days, weeks, or months. It varies depending on what part of today’s vehicles you’re referring to, but the average answer tends to be about a month or so. Today’s car and truck alternators are self-charging. That is, they produce enough juice to keep themselves going all the time.

When they fail and stop producing enough, the battery then becomes the sole source of running your vehicle’s many electrical components. The typical everyday driving habits of most people usually can’t drain a good battery in less than a month, but if an alternator fails, it can discharge a healthy battery rather rapidly.

Can an alternator test good but still be bad?

YES! An alternator can test well even though the alternator is bad. This can be demonstrated using a voltmeter. It is important to note that this only works with a digital voltmeter (DVM).

A DVM can be in one of two states; digital or analogue. A DVM in the digital state will measure the voltage accurately just like any other digital device, it will either be on or off (1 or 0).

How can you tell if you need a new alternator?

When an alternator stops working, your car’s battery will still be OK for a while. Without an alternator to recharge it, however, your battery will run down in a very short time. If your battery has been low lately, if your engine is starting hard, or if you are getting lights on your dash because the battery is too low even to operate the electrical system, then you may just need a new alternator.

Also, once the wire connection is good, the battery is in healthy condition but it keeps draining. It might be that the alternator is not charging it and you might have to consider changing it.

Can a parasitic draw ruin a car battery?

Yes, it can. The parasitic draw occurs when a component in the car continues to draw power from the battery after the ignition has been switched off. The most common reason for this is a clock, which uses between five and 30 milliamps even when it’s not receiving power from the alternator.

When leftover time, even for a few hours, the power drain can be enough to damage the battery. If you are leaving a vehicle unused for more than a week, disconnecting and removing the battery will help prevent damage from a parasitic draw.

What causes parasitic drain on car battery?

A parasitic draw occurs when an electrical device continues to draw power even after it is switched off. It can quickly drain a car battery, and if your engine immobilizer is linked to the battery, a parasitic draw can prevent you from starting the engine.

To be sure you don’t experience parasitic drain, turn off any accessories that can accidentally start to drain your battery when your engine is off, like heated seats, GPS systems, and radios.

Parasitic drain test

The parasitic drain test shows how much current is consumed when no load is connected to the load terminals of a power supply or no load is connected to it. By connecting an ammeter in series with the power supply and circuit, the current consumption can be observed and compared with that at the time of full-load operation.

By performing the parasitic tests on your vehicle, you can get the most out of your vehicle’s parasitic drain and the loss of power through devices such as garage door openers, tire monitors, and anti-theft systems.

How do you fix a parasitic battery drain?

A parasitic battery drain is when electricity is being drawn from the vehicle’s battery and converted to heat by an inoperable accessory or part of the vehicle. If you have a parasitic drain, the best solution is to replace the failed part.

However, if you can, replacing a part before it fails will prevent damage from being caused to the vehicle, and help improve fuel efficiency. If the cause is something you can fix rather than replace, then fixing it is certainly a good thing to do.


Do you wonder why your car battery keeps dying but alternator is good? It is a common thing that happens to most car owners and you are not alone. So, on this page, we have all that you need to know about why the battery keeps running down with a good alternator and how to prevent future occurrences

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