Can You Overcharge A Car Battery? Causes and Effects | Autance

Most car owners often overlook the condition of their battery, especially if it’s overcharged or under-charged. For instance, if your vehicle has stayed unused for quite a long time, you’ll want to charge it so that your car can do whatever you ask of it. Well, can you overcharge a car battery? This is a…

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Can You Overcharge A Car Battery? Causes and Effects | Autance © Can You Overcharge A Car Battery? Causes and Effects | Autance

Most car owners often overlook the condition of their battery, especially if it’s overcharged or under-charged. For instance, if your vehicle has stayed unused for quite a long time, you’ll want to charge it so that your car can do whatever you ask of it. Well, can you overcharge a car battery?

This is a very simple question and yet a tricky one, for that matter. But the answer is yes; you can overcharge it. Nevertheless, this article will provide you detailed information concerning this issue.

What Can Cause a Car Battery to Overcharge?

Damaged Alternator

Most modern vehicles are charge with an alternator, which provides them with controlled and steady electrical charges while driving to keep your car charged. In addition, the alternators have a voltage regulator, specifically tasked to regulate the amount of voltage emanating from the alternator onto the battery.

If the regulator has a glitch, it allows your car battery to accumulate extra voltage, thus overcharging it. The voltage regulator is designed to maintain the voltage it sends to the car battery below 15V.

If it exceeds this minimum voltage, it will be overcharged and eventually get damaged. If it becomes extremely hot to touch or the top part starts, these are the signs of overcharging it.

Unattended Trickle Chargers

Another cause of overcharged car batteries is using trickle chargers. Ask yourself this question “can you overcharge a car battery with a trickle charger?” Definitely, yes this is because trickle chargers provide the insignificant amount of electric currents sent to the battery, thus charging it very slowly.

If you don’t attend your trickle chargers, your battery will be overcharged by an additional 12.7 volts. Some of these chargers cannot detect when it’s completely charged to stop sending

electrical charges or energy to it. Therefore, if you intend to purchase a trickle charger, acquire one which can detect if your car battery is fully charged to avoid the risk of overcharging it.

Defective Regulator

If the voltage regulator is not functioning properly as intended, your battery will be overcharged or undercharged. The regulator is part of the alternator, and it maintains a constant flow of electric voltage to your vehicle’s battery.

So if the regulator is faulty, it tends to send excess or less electric charges to it. If you notice this problem, replace the regulator immediately to avoid further issues. In addition, before replacing them, ensure they are properly connected to the alternator.

Damaged Car Battery

A defective battery gives your charging system false voltage readings. Thus, this can cause the alternator to either increase or reduce the voltage output. Moreover, the faulty battery cannot hold a charge for a long time, no matter how the alternator tries to charge it.

In turn, the alternator is overheated, causing it to fail. Therefore, the only option is to replace it if you get the chance.

Excess Heat

Summer season comes with excess heat that can radically damage the condition of your battery if exposed to the sun. The excess heat can exacerbate the problems caused by overcharging. It can be difficult to avoid this problem if you live in such hot areas.

To solve this problem, first, you need to avoid overcharging and ensure that your vehicle gets enough shade and should be properly ventilated.

Effects of Overcharging a Battery

Overcharging batteries is very dangerous and problematic since it’s quite hard to notice, and the outcome can be severe. It lowers your battery’s lifespan and efficiency, as well as the inability to ignite your car. So, what happens if you overcharge a battery?

To fix this human error, most manufacturers have produced batteries that simply die if you overcharge them. Nevertheless, there are side effects; for instance, as your battery overcharges, the mixture of distilled/filtered water begins to boil.

The boiling generates a lot of heat and creates pressure causing it to swell. In addition, the heat can also cause the plastic coating to melt, leading to the introduction of hydrogen, which is extremely flammable. The swelling caused by the gas creates some vents or fissures.

Once hydrogen reacts with oxygen, you ultimately drive on a time bomb that can explode anytime, which is a very scary scenario. Nevertheless, this is a possible outcome if it gets extremely hot.

In most scenarios, if it is overcharged, the hot liquid components weaken its casing. This significantly shortens its lifespan; thus, you can’t get the most out of it. So, can you overcharge your car battery?

Can you overcharge a Car Battery?

Overcharging it can have several negative implications, especially on its lifespan. Fortunately, overcharging is not a common problem. Still, it only arises from some issues related to charging, such as damaged alternators and if you leave trickle chargers unattended.

The simple answer to the question above is yes; you can overcharge it. This is because it can withstand excess voltage sent to it, even if it’s fully charged. Therefore, it’s upon the alternator to send the required amount of voltage.

Most car battery charger available in the market use lead-acid and can withstand high voltages. The main effect of overcharging is that the battery can be boiled dry, thus damaging the lead plates internally.

Why You Should Charge a Car Battery

Storing your car, particularly during winter, can pose some serious challenges if you don’t start the vehicle periodically to allow it to charge. If you intend to store it for several months, you should use a battery maintainer/charger to charge it while not using it. If you do this, you reduce the risk of freezing it during the winter months, and it stays alive when you want to use it.

If you buy a new car battery, you need to charge it first before using it. Batteries always lose their electric charges while on the shelves as they await to be bought. They become extremely weak, and that’s why you should charge yours first before using them.

Alternators are not designed to charge your car battery but to top it off. If you allow the alternator to charge a dead battery, it becomes a challenge to it, which is why you need to charge your battery before using it.

You should also charge it due to its complex composition. For instance, the internal cells are lead-plated and are also surrounded by distilled water and concentrated sulphuric acid. And after some time, the lead sulfates will be deposited around the lead plates resulting in the crystallization of these lead sulfates.

Eventually reducing the capabilities to retain power and limit its charging power as well. To avert sulfation, you need to discharge and charge it regularly. This will convert the crystalline deposits into electric sulfates, which lead plates can again convert into electric charges (electricity).

Frequently Asked Questions (FAQs)

Q1. How do I know that my battery is fully charged?

The car battery plays a significant role in igniting it, and it is about 12V, which means that if it’s fully charged, it reads 12.6V if your car is turned off. You can read its voltage while your vehicle is running if the alternator is functioning properly.

While driving, you should get higher voltage readings ranging between 13.6 to 14.8 volts. Nevertheless, most chargers can read the volts emanating from your vehicle while at the same time detecting if it’s fully charged. This is highly convenient because you need not break the multimeter to read the voltage.

Q2. For how long should I charge my car battery?

The time it takes to charge is dependent on the rate of its amperage, that is, 48 amp-hours. To mean it can take you 12 hours to charge it if you use a 4-amp charger. In contrast, it takes 48 hours with a 2-amp charger.

Q3. What can make my battery explode while driving?

Batteries are perfectly built to be used safely without exploding under normal conditions. Technically, it can only explode if its leads are crossed or if it has been subjected to external blow. Nevertheless, you don’t need to worry about its explosion during standard operations.

So the risk of your battery exploding while driving is very low. It can only happen if your car crushes or when you accidentally mix up the negative with positive terminals while jumpstarting it.

Q4. Can I leave the battery to charge overnight?

Of course, you can leave the charger on overnight. This is possible if it can detect when it is charged fully. You should also ensure that the charger is fully functional and not faulty.


Can you overcharge a car battery? No, you can’t do that; instead, you must avoid it by all means possible. This is because overcharging it will not only reduce its lifespan but also kill it. Moreover, it can be detrimental to your vehicle.

Most importantly, ensure the alternator is functioning properly and your charger is not defective. Human error can also cause overcharging, so if you are not sure how to go about it, seek help from a professional mechanic. You can also repair it through the reconditioning process.

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