6 Reasons Why Your Car Battery Is Not Charging & Solutions

Is your car battery not charging? Such an inconvenience can quickly derail your plans for the day. It’s a common problem that can arise for several reasons, from simple, such as an old car battery, to more complex, such as a faulty alternator. Either way, a car battery not charging can bring your journey to a halt.

Whether or not you should seek a mechanic’s advice will largely depend on the symptoms and their intensity. Some reasons for battery problems may be easy to resolve, while others can be more challenging.


Driving with a failing car battery can lead to a sudden breakdown, leaving you stranded in the middle of the road. If the dashboard lights dim or the engine fails to crank properly, avoid driving until you address the issue.

Why Is My Car Battery Not Charging?

While sometimes the reasons can be apparent, like leaving the headlights on overnight, the cause can be elusive at other times.

Listed below are six reasons why your car battery might not be charging:

1. Old or Damaged Battery

The first thing to consider is the battery itself. If it’s old, dead, or damaged, it won’t recharge as it should. A car battery typically lasts 3-5 years, but this duration can be shorter depending on driving conditions and habits. 

As batteries age, their internal components deteriorate, reducing their ability to hold a charge. Extreme temperatures, frequent short trips, or prolonged periods of inactivity can accelerate this wear – and be devastating.

Furthermore, physical damages or factory defects can also compromise battery integrity. When a battery cannot store enough power or deliver the required current to start the engine, it might be at the end of its lifespan and require replacement.

2. Corroded Terminals or Loose Battery Cables

An efficient flow of electricity is crucial for the battery to charge. The battery terminals, being exposed, are prone to corrosion over time. This corrosion can manifest as a white or blue powdery substance on the terminals. 

Not only can this prevent the battery from transmitting power, but loose or damaged connectors can further inhibit the battery from charging. 

Tighten the connectors and clean the battery terminals if they look corroded.

3. Faulty Alternator

The alternator is the heart of a car’s electrical system. When the engine is running, it supplies power to your car’s electrical components, such as the AC, power windows, or radio.

But that’s not all. It’s also responsible for recharging the battery. If it’s not recharging as it should, you might find the cause by looking at the charging system. In other words, the drive belt, alternator, and in some cases, the wirings. 

Also, pay attention to other signs, such as dim lights, the battery light coming on, or the smell of burning rubber. Either way, you’ll want to test the alternator and charging system.

4. Parasitic Drain

When you turn off the ignition, the car’s electrical system cuts off most power-consuming activities. However, most vehicles have a “normal” battery drain, typically between 50 and 85 milliamps (mA) in newer cars and less than 50 mA in older ones. Any drain beyond this is considered a problem.

When it does happen, it’s typically due to faulty components or systems that continue to drain power when not supposed to, called a ‘parasitic drain.’ Such a thing could be malfunctioning door lights, interior lights, or even bad relays.

Over time, even a slight increase in battery drain can deplete the battery. And if the car remains stationary for extended periods, you’ll likely find the battery flat, which easily can ruin your day.

5. The Headlights Were Left On

Most of us have been in a situation where we inadvertently left the headlights on. With all the technological advancements in cars, it’s easy to assume that headlights will automatically turn off when shutting off the engine, but this isn’t always the case. 

Many vehicles, especially older models, do not have an automatic shut-off feature for headlights. When the headlights are left on, even if it was an honest mistake, they can drain the battery to the point where there isn’t enough power left to start the car.

6. Malfunctioning Electric Control Unit (ECU)

While a malfunctioning Electric Control Unit (ECU) is not nearly as common as the other causes, it can be a potential cause for a car battery not charging. The ECU is a crucial component of a car’s electrical system as it controls and manages various functions, including the charging system.

Hopefully, you’ll notice a Check Engine Light as soon as the ECU fails. But if you’re unsure, it’s better to have a technician diagnose it immediately.

How to Fix a Car Battery Not Charging

When there are so many reasons for a car battery not charging, it’s always good to test the output from the alternator before proceeding. If there’s something wrong with the voltage, it could quickly leave you with a damaged car battery again. 

Check the battery connections

Make sure the battery terminals are clean, and the cables are tight. To do this, locate the battery and use a wrench or socket to loosen or tighten the bolts on the connectors. If you remove the battery cables, start with the negative clamp marked with a “-” and replace them in reverse order, starting with the positive.

Jump-start your car

If you have access to another vehicle with a working battery, you can try jump-start your car. This involves connecting jumper cables between the two batteries and allowing the working battery to charge your dead battery.

Replace the battery

Replace it with a new one to see if it was the battery itself. To save you some bucks, you can see if any friend has a spare battery to lend you. But if the old battery is over five years old, it’s probably time to replace it anyway. Ensure the new battery is the correct size and type for your vehicle. Check your owner’s manual or consult a mechanic for more clarification.

Check the alternator

As discussed, you’ll want to test the alternator for low voltage output, but also that it’s not too high and damaging your battery. But before doing so, you need to get your engine running. If the alternator is faulty, it likely has to be replaced.

Take the car to a mechanic

If none of these steps work, it may be time to take it to a mechanic. They can test the battery and alternator to determine the root cause of the problem and do further troubleshooting if necessary.

Why a Car Battery Charger Won’t Work

Having understood the causes above, most of which are related to things other than the battery, there is another aspect to consider: a battery charger that does not charge. So while you may assume the charger will solve the issue when the battery is down, sometimes, even the charger won’t work as expected.

Here are some examples of why the car battery charger won’t help you:

  • Battery Voltage Is Too Low: Some smart chargers require the battery to have a minimal voltage before charging. A charger might not detect it if it’s already excessively drained.
  • Battery Is Completely Dead: Sometimes, a battery might be so drained or damaged that it can’t take charge. If so, the car battery charger won’t be much of a help.
  • Charger Compatibility: Not all chargers are suitable for all types of batteries. Always ensure the charger you use is compatible with your vehicle’s battery.
  • Damaged Charger: The charger itself might be faulty. Ensure the cables, connectors, and the main unit are in good condition. You can also test with another charger.
  • Poor Connection: For a charger to work effectively, it needs a solid connection. Ensure the charger’s clamps are properly connected to the battery terminals and are free from rust or corrosion.
  • Non-operating Environment: Chargers often have an optimal operating temperature range. Therefore, it might not work if you’re trying to charge a battery in extremely cold or hot conditions.

How to Prevent Battery Charging Issues

The best approach to any problem is prevention. Regularly inspecting the battery, ensuring no electrical leaks, and following the routine service schedule can help avoid battery charging issues. Furthermore, investing in a high-quality battery and ensuring it’s correctly installed and securely fastened can make a significant difference. Here’s a checklist for maintaining your battery:

  • Regularly inspect the battery.
  • Keep your battery terminals clean.
  • Make sure the battery is fastened correctly.
  • Drive your car regularly.
  • Avoid leaving accessories on.
  • Replace the battery every 3 to 5 years.
  • Check your charging system.
  • Properly store your battery when not used.

How often should you test your car battery?

According to Jiffy Lube, checking and testing your battery at least twice per year (every 6 months or 6,000 miles) is typically recommended. However, you’ll find the specific schedule for your vehicle in your owner’s manual.

Warning Signs to Seek Professional Help

It’s essential to be observant of the warning signs that indicate battery issues:

  • Dimming headlights or interior lights.
  • Engine cranking slowly or not starting.
  • A clicking sound when turning the ignition key.
  • The battery warning light is illuminated on the dashboard.
  • Frequent jump starts are needed.

How can I check for a flat battery?

To check for a flat battery, you can use a multimeter set to the DC voltage setting and connect the red and black probes to the positive and negative battery terminals. The battery is likely discharged or flat if the reading is below 12.4 volts.

What is the difference between a flat and a dead battery?

A flat battery refers to one that has been discharged, often due to leaving lights on or not driving the vehicle for a prolonged period, but it can usually be recharged and restored to full functionality. On the other hand, a dead battery has reached the end of its lifespan, can’t hold a charge anymore, and typically needs to be replaced.

Will a jump-start work if the alternator is bad?

If the alternator is bad, a jump start can help the engine to start using the power from another battery. However, once disconnected, if the alternator isn’t functioning properly, the battery won’t recharge, and the car might stall out again.

Should I replace a battery that can’t hold a proper charge?

Yes, if the battery can’t hold a charge and you more frequently find it flat, it’s advisable to replace it. However, you also want to ensure the charging system properly charges your battery.

How does a mechanic check the battery charge?

A mechanic typically uses a multimeter or a dedicated battery tester to check the battery’s voltage and state of charge. Some advanced tools also measure the battery’s cold cranking amps (CCA) and overall health.

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Rickard Cefalk

Rickard is the owner of Caraspect.com and a dedicated and avid do-it-yourselfer who has always enjoyed working on his own vehicles since childhood. He now devotes his time to sharing his expert knowledge of car maintenance and other car-related information through his website.