What Are The Signs Of An Overcharged Car Battery?


A car battery is one of those components you install and forget about, at least until it gives you problems. Thankfully, they’re not too problematic other than dying out at the end of their lifespan. But, unfortunately, a battery that overcharges is also bad, if not worse, than one with no charge at all.

Signs of an overcharged car battery include high voltage readings and overheating. Besides that, a swelling or leaking battery is likely experiencing an overcharge condition. You can also look for indirect signs of an overcharged battery like headlights that blow and need to be replaced more often than usual.

You can deal with an overcharged battery early by recognizing the signs mentioned above. This guide will walk you through each of them and even teach you why this problem happens in the first place.

Overcharged Car Battery; What Are The Symptoms?

An overcharged car battery is a very dangerous thing. Thankfully, there are plenty of clear symptoms that you can look for to catch the problem early so you can solve it safely.

Here are 5 of the most common signs that your car battery is experiencing an overcharge condition:

1. High Voltage Readings

The first and most direct way to know if your car battery is overcharged is by checking its voltage readings. Some vehicles have battery voltage indicators, though you can also use a standard multimeter for the same purpose.

Typically, a car battery will be between 11.7 volts and 12.6 volts while the engine is off. However, when the engine is turned on, and the alternator actively recharges the battery, you might see the voltage go as high as 14.8 volts.

If you get a voltage reading above that maximum number, that’s confirmation that your battery is overcharged.

Of course, it’s not practical to monitor your battery for overcharging by using a multimeter every single day. Thankfully, there are other signs you can look out for as well.

Those signs are detailed below.

Read: What Causes a Car to Pull to One Side and How to Fix It?

2. Overheating Battery

All car batteries will become a little bit warm as they charge. That’s because heat is a natural byproduct of a recharging or discharging battery.

However, a car battery should never reach extremely high temperatures. When you touch the battery’s case with your hand and feel it overheating, that’s another clear sign it’s overcharging to a dangerous level.

At this point, you must disconnect the battery and dispose of it immediately. Continuing to use the same battery is incredibly dangerous for you and your car.

Read: Can Bad Motor Mounts Or Spark Plugs Cause A Car To Shake When Idle?

3. Headlights Burn Out Often

An overcharged battery will also cause indirect symptoms, like headlights burning out often. A typical car headlight will burn after thousands of hours of use.

But if you find yourself replacing your headlights more often than usual, the problem might be with something other than the lights. Instead, the overcharging battery could be causing its excess voltage to flow to the lights, causing them to fail prematurely.

If you think that’s what’s happening, inspect the battery thoroughly when you replace your headlights.

4. Battery Leaking

A battery that’s storing too much charge inside will also display physical symptoms. You can look for these symptoms by checking your engine bay and shining a flashlight at the battery.

The first physical symptom to look for is a battery leak. Car batteries contain fluid that must be trapped inside at all times. In other words, you should never see a car battery that’s wet on the outside.

A battery that’s leaking fluid is damaged and must not be used. The most likely cause of that damage is overcharging, which causes the fluid inside to leak through any openings the battery has.

Read: Why Car Is Shaking When Braking At High Speeds?

5. Swelling Battery

Earlier, you read that an overcharged battery will overheat and cause its fluid to leak. That can also cause another sign of an overcharged battery: swelling in the battery case.

The battery case consists of a hard plastic that always stays the same shape.

However, overcharging can cause the pressure inside to increase to dangerous levels, so much so that the casing swells and develops a bulge on the side.

Read: Why Your Car Sputters When Starting But Then Runs Fine

Why Is My Car Battery Overcharging?

Aside from recognizing the signs of an overcharged car battery, it’s also crucial to understand why overcharging occurs. That way, you can ensure that your replacement battery doesn’t experience the same problem.

Here are some of the most likely causes behind car batteries overcharging:

  • Faulty charger: Many car owners remove their batteries and keep them topped off using an external charger. Unfortunately, a faulty charger can send too much charge into the battery, especially if its safety features aren’t working.
  • Alternator issues: The alternator is the part of your car that always keeps the battery recharged. It converts the engine’s power to electricity that’s supplied back into the battery. Unfortunately, a problematic alternator won’t know when to stop charging the battery, thereby causing an overcharge condition.
  • Human error: Despite how car batteries work with chargers or alternators, human error can also cause them to overcharge. For example, choosing the wrong charger or selecting a voltage setting that’s too high will cause the battery to experience an overcharge condition. Besides that, leaving the battery to charge overnight without removing the charger can also cause the same problem.

Can A Battery Recover From Overcharging?

No, a car battery cannot recover from overcharging. Unfortunately, that means you can’t save the battery by simply draining the excess charge.

When a battery experiences overcharging, there’s a strong likelihood that its internal components are already damaged. Plus, its case is likely compromised by the overheating and excess pressure generated inside the battery.

Not only is an overcharged battery not recoverable, but it also poses a significant danger to the vehicle and its occupants.

Read: 3 Signs That Car’s Transmission Is Slipping And Has A Serious Problem

What Do You Do When Your Car Battery Is Overcharged?

When you recognize the signs that your car battery is overcharged, the best thing to do is disconnect and remove the battery immediately. You must place the battery somewhere safe and dispose of it correctly as soon as possible.

As you read in the previous section, there’s no way for you to recover an overcharged battery. Not only that, but it would also be too risky to do so as the battery is likely damaged from within.

So, the only straightforward solution is to replace the battery with a new one. However, there are a few things you must keep in mind.

Firstly, make sure that you purchase a high-quality replacement. Well-built batteries from reputable brands will have less likelihood of causing problems, so they’ll potentially save you from many headaches.

Besides that, you must identify and resolve the issue that caused the overcharging in the first place. For instance, replace any problematic alternators or chargers, and check to ensure that you’re using everything correctly.

That way, you can prevent your new battery from being overcharged the same way as the last one.

Final Thoughts

An overcharged car battery is a very dangerous thing. Thankfully, there are several ways you can identify and fix the problem quickly before it leads to bigger problems.

Check for excess voltage, and look for physical signs like leaking and swelling. Besides that, look out for indirect symptoms like headlights that need to be replaced too often. When you understand these symptoms, you can rest assured knowing that a potential battery overcharge won’t go unnoticed.

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