Car Battery Keeps Dying but Alternator is Good

The battery is dead. More precisely, the battery is going to die. But everything has its time. When the battery runs out frequently, then your car has a problem.

That’s right, our first suspicion is the alternator in case of frequent battery drain.

Now, let’s assume your situation.

After this car battery problem, you can perform some tests to determine the condition of the alternator. But it seems to be OK. So, your situation is: your car battery is dying, but the alternator is good. right?

There may be several reasons behind this situation. This short article examines the possible causes and discusses some ways to fix the problem.

Now, let’s take a look at the details-

Car Battery Keeps Dying [Symptoms]

1. Faulty Battery

The battery has a long service life and is constantly being depleted and half charged. Battery life is reduced when combined with external conditions such as high temperatures or severe cold.

Remove the battery from the car, if necessary, and then fully charge it if you have a battery charger. Better yet if you have a contemporary maintenance battery charger. These can sometimes revive completely dead batteries. You can also diagnose a defective battery by using the battery charger.

If the problem persists after the battery is fully charged, consider replacing or fixing the battery.

2. Corroded Connections

The battery and vehicle cable must be properly connected. Electrical resistance may be caused by damage, corrosion, or loose connections, preventing the battery from charging effectively.

The first thing to check for is rust around the terminals and cable ends. It usually takes on a white, spongy appearance and can completely cover the connection. Disconnect the battery and, if necessary, remove it from the vehicle for easy access. To clean the terminals, you can use industrial cleaners, steel wool, or even sandpaper. Baking soda can also be used to clean the terminals after soaking them in white vinegar.

You can clean the terminals by disconnecting them from the battery. Battery terminal problems are not uncommon. Replace any purple or white bubbles you see on the bottom of the terminal.

Reinstall the battery and check to see if the problem is solved. Make sure the cable is securely attached to the termination.

3. Problem with the Ground Connection

If your drive belt is in excellent condition, you can move on to the next chapter. This is known as the battery connector.

It only takes a few loose connections to bring your car to a stop.

So make sure all connections are clean and secure. In short, check if the terminals and cables are in excellent working order. The flow of electricity will be impeded if these components are corroded or damaged.

4. Find Parasite Drainers

Most people’s initial question is: “What is parasitic battery drain?”. Parasitic battery drain is defined as anything that causes the battery to discharge after the power switch is turned off.

The most typical parasitic drain, for example, is a short circuit somewhere. This will quickly drain the battery. Another problem may be that the interior lighting or the trunk lights are not properly turned off. The glove box light is less noticeable.

The ignition circuit may be faulty. This can cause the radio to continue to play even after the vehicle is turned off. Most car radios have a timer, which means that the radio will turn off after a set time, usually one hour. This can create problems if it fails.

How to fix the parasitic drain problem

Fortunately, finding the parasite discharge is a difficult task. On the other hand, finding the underlying reason may be more difficult. This test will require the use of an ammeter. You can borrow one or buy one for a very low price.

Follow these procedures to perform a parasitic drain test:

  • Check that the car’s ignition switch is turned off.
  • Check that all electrical appliances in the car are turned off.
  • Close all doors and the trunk.
  • Disconnect the negative battery cable.
  • Connect the ammeter in series to the negative cable:
    • Connect one of the terminals of the ammeter to the negative cable of the vehicle.
    • Then connect the other connection of the ammeter to the negative terminal of the battery.

After connection, the ammeter should read 0.2 amps or less. If it reads more, you have a problem with the battery.

Finding the problem requires a little detective work. Follow the steps below:

  • First, you must locate the fuse box.
  • Pull out one fuse at a time and recheck the ammeter.
  • If the current is less than 0.2 amps, you have discovered a problem in the circuit.
  • If the problem persists, replace the fuse and try again.
  • Once you have identified the circuit, you should be able to locate the source of the problem. A little more investigation should quickly reveal the source of the problem.

On rare occasions, the problem may be caused by two or more circuits. In this case, as you pull each fuse, the ammeter measurement will decrease a little. Note which circuit it is and keep pulling the fuse until the ammeter registers 0.2 or less.

5. Drained Battery

If you do not drive your car frequently, the battery will drain. It is a common myth that if you turn everything off in the vehicle, the battery will remain fully charged.

Even while the car is parked, the battery will use a modest amount of energy. It is only measured in milliamps, but it will eventually drain the battery completely. How long this takes depends on the condition of your battery.

Another typical mistake is to use your car only for short distances. Starting the engine puts a great strain on the battery. A few kilometers do not allow for a full charge. The battery will eventually run down and will be unable to run the engine.

There are two methods to avoid draining the battery:

  • In maintenance mode, use the battery tender and plug it in every time you park the vehicle at home.
  • Drive long enough to charge the battery. This usually takes about 20 minutes by car. When the lights are on at night, it will take longer.

6. Wiring Problem

Wiring problems can be more difficult to identify and resolve, but there are some basic steps you can take. When inspecting the cable, consider the following:

  • The outer jacket is damaged. This is the insulating layer that prevents the wires from meeting any metal and corroding.
  • Corrosion of terminals and plugs
  • Anywhere where the cable is tightly wound. This can cause interior damage that is not visible.

The following are some examples of common cables to inspect:

  • The cables that connect the battery to the fuse panel are as follows: Usually located under the hood, although some cars store them in the trunk.
  • The cable connecting the battery to the ignition switch.
  • The link between the alternator and the battery. The defect can be identified by inspecting the alternator output. If the output is satisfactory, carefully inspect the cable. To check the alternator output, first, make sure that the fuse is not blown. Now, take a reading of the battery voltage. When the engine is running, the voltage should be about 14.5 volts. This indicates that the alternator is supplying enough power to charge the battery. If it is not, the problem could be in the wiring.

7. Problem with the Sun Visor

On the sun visor mirror of many cars is a small light. This can drain your battery for two reasons:

  • The sliding cover does not turn the lights off. The light stays on, and its charge will drain overnight.
  • There may be a short in the cable, causing the light to stay on all the time.
  • To avoid draining the battery, remove the fuse from the rearview mirror bulb in any case. You now have time to remedy the problem or refer it to a technician.


What can drain a car battery when the car is off?

Even if your car is turned off, the battery will continue to power electronic devices such as clocks, radios, and alarm systems. These factors should not have a significant influence on your battery. However, when the car battery is off, interior lights, door lights, and even damaged fuses can drain the battery.

Can a bad starter drain a battery?

The battery will discharge if the starter fails. It may absorb an excessive amount of energy or continue to consume energy.

Why is my car battery draining so fast?

A short circuit can cause a high current draw and battery drain. Check for loose or worn alternator belts, circuit faults (loose, disconnected, or broken wires), or faults in the alternator charging system. Excessive use of the battery at start-up can also be caused by engine operating problems.

Why does my car keep dying with a new battery and alternator?

Loose or corroded battery connections, continuous power consumption, charging problems, persistent need for more power than alternators and even inclement weather are some of the most common reasons for recurring automotive battery failures.

How do I know if my battery is bad or my alternator?

Some of the problems to watch out for are inability to start and difficulties in starting, dimming of lights, and difficulties in outputting the sound system. If the vehicle starts but shuts off while driving, the battery may not be able to charge due to a faulty alternator.

Final Thoughts

The battery and charging circuit problem is not only inconvenient, but also costly.

It is inconvenient to often start your car only to discover that the battery is dead. You’ll be late no matter where you go, and it could be dead again by the time you get home.

However, it can also take a toll on your wallet. Letting the battery go fully discharged on a regular basis will reduce its lifespan. It can also put additional strain on other sections of the vehicle.

In summary, if you detect a billing problem, resolve it as soon as possible. It will be less costly in the long run.


Hi, I'm the initiator and writer of this blog. Cars were and will be my first love, and my favorite hobby, that's why I decided to start this blog and write about my discoveries and techniques to improve my cars or repair them.