Home Diagnosis and TroubleshootingBattery and Charging Is A Car Battery AC Or DC: The Basics You Should Know

Is A Car Battery AC Or DC: The Basics You Should Know

by Jordan Harris
Is A Car Battery AC Or DC

We are aware of the concept that every mechanical and electric device use to get energy. It is a fact that all mechanical and electrical gadgets rely on power. It is supplied from a source to function efficiently. These sources of energy can either be a battery, electricity, gasoline, geothermal energy, etc. But one thing makes things a bit complicated. A car. Which source of energy specifically does a car run on? A car makes use of multiple sources of energy ranging from petrol, CNG, diesel, electricity, etc. Despite running on all these sources of energy, it still requires a battery. Then more questions arise. What kind of battery? Is a car battery AC or DC?

Well, probably this might have left you with more questions than answers. What would be the purpose of a battery if a car runs on fuel? A car battery is a very essential source of energy during the ignition process. It is the battery that helps to jump-start the engine. After the car is ignited, it’s the rotation of the engine that drives the alternator, forcing electrical current into a battery where it is stored as chemical energy.

Besides ignition of a car, a battery also performs different tasks that range from; turning on lights inside and outside the car, running a car’s music system, running the GPS navigation system, providing current for the headlamps, and powering the DVDs, therefore, making the battery an essential car component.

Batteries are of two different categories, a DC or an AC. This variation depends on the electrical purpose upon the requirement. In this article, we decipher the difference between AC and DC and know the one used in cars.

Contents of this article entail;

Is A Car Battery AC Or DC: The Basics

Modern vehicles consist of various systems that work in harmony with each other. You cannot eliminate one part from these systems and still expect optimal efficiency. These can even lead to a total breakdown of the entire system. The car won’t even move an inch. We may say that a car’s electrical system is one of the greatest things it has. This is because modern gear technology is quickly shifting to a hybrid and electric future.

The term electricity refers to the movement of electrons through a circuit with both positive and negative terminals. To provide power to things like motors, manufacturers have invented chemical cells which have got a high electric capability than are used in cars.

Car batteries can be charged, and this helps to provide electrical flow to an engine. The role of a battery in a car is to supply the starter with electricity. This enables it to ignite the motor. After the motor has been ignited, control of the vehicle’s electrical system is now provided by the alternator.

Is A Car Battery AC Or DC: Difference Between AC And DC

As mentioned earlier there are two different types of batteries depending on your need and the electrical purpose of application. The two main technologies applied in car battery manufacturing are the AC and the DC technology. But what is the difference?

Direct Current (DC)

This means the flow of electrons in one particular direction. DC power possesses a voltage with a constant polarity which is either positive or negative. This type of current is made by a battery and can pass from the positive to the negative terminal of the battery. DC power usually ranks higher than AC power because it can be easily stored even on a small scale for later use.

Historical archives have it that it is this type of current that was utilized by Thomas Edison to power his first transmission system. The DC power is mainly used to power small electronic appliances like radios, microwaves, laptops, and many more.

Advantages Of A DC Battery

DC power is only provided by batteries. A battery can easily transform chemical energy into electrical energy through internal chemical reactions. These chemicals are usually stored inside the battery. The major function of the battery is to provide energy to other parts of the system.

DC electricity only moves in one direction and never reverses. This means batteries can transmit a large amount of power with greater efficiency at a very minimal cost. A battery also can store power in terms of chemical energy for a very long time with no added converters.

This form of chemical energy can easily be transformed into electrical energy when the need arises. Energy stored on a battery is also very portable as it can be moved from one place to another with ease.

Alternating Current (AC)

Alternating current is the continuous flow of current into changing directions. This type of current was first put into use by Nikola Tesla to power the transmission system that he had invented. Currently, there are no AC batteries available. There are only a few DC batteries that are fitted with converters to help convert the DC power to AC.

One main advantage with AC power is that it can flow into two different directions and this gives it the ability to carry electrons to very long distances without diminishing in power. Batteries with AC converters are more efficient as a source of energy and come with an added benefit in that they are capable to store this energy in a portable unit.

Is A Car Battery AC Or DC?

Well, all car batteries are DC. This is simply because AC power cannot be stored in batteries. There are a couple of reasons a car battery runs on DC power.

One is that AC power changes direction often, probably 50 times per second. Therefore, to store AC power in a battery, it would require the battery to change the polarity of its terminals at the same interval: 50 times per second, which is nearly impossible.

Second, if an AC supply is connected to a battery to store AC power that means the battery can only charge during the positive half cycle and will discharge the power again during the negative half cycle this means the average current or voltage in a full cycle would equate to zero meaning there is no way AC power can be stored in a battery.

But to make things clear, even the DC power cannot be stored in a battery either but can be converted into chemical energy and stored in a car battery for future use. Just as we had said earlier, all batteries run on DC. This means that a car battery to runs on DC power.

But one thing to note is that the rest of the car may need AC power. For DC power to work on an AC system, it has to be converted into AC using additional circuits.

AC power can be produced from a DC battery through an AC converter and this is installed in cars for this specific function. DC is more popular with low voltage applications of electricity like your car.

Is A Car Battery AC Or DC

Batteries can also be charged using the DC power as well hence AC is always converted to DC first when the major component of the system usually involves a battery.

How A Car Battery Works

A standard car battery would store 12 volts and have a capacity of 200 to 225 amp-hours (Ah). This type of battery can be charged by driving your car. But this does not guarantee full charge in case the battery is completely drained. The alternator that does this charging process will not be able to provide 100% output in charging the battery back up to 12 volts.

The alternator can only achieve a 15% of its usual charging capacity in this case. This is mainly because the alternator also helps to power other vehicle accessories. Many cars use batteries sealed using lead-acid while hybrids or EVs use lithium-ion batteries. Batteries that have a lead-acid design comprise of 6 cells that can emit 12 volts output.

Their capacity greatly depends on the energy, and the size required by your car. Car DC batteries have got a relatively low amp hour rating. This means that they don’t have a bigger reserve power to manage to provide electrical energy for a lot of electrical components for a very long time.

For a car battery to work and help in starting the engine, it will need additional circuits to convert the DC into AC. This is usually done by the AC converter. Over time the efficacy of car batteries begins to deteriorate. One of the main causes is completely draining the battery. This eventually damages the cells of your battery.

How An AC Alternator Works

The alternator comprises a belt that enables several accessories to function and this includes the pulleys; one for the engine and the other for the alternator itself. The alternator will also provide power that is used to power other electrical accessories like headlamps, turn signals, vehicles stereos, and not just charging the battery alone.

The alternator usually produces AC output. This output is immediately converted into DC for use. Previously cars had DC generators that helped provide electrical power. However, these DC generators were later replaced by alternators because the electrical consumption in a car had significantly increased. The alternator was more efficient at charging and could easily produce high output even at low RPM.

The alternator produces AC power. Since the AC is rarely used in electronic gadgets in the car, it has to be converted to DC. Hence there are full-bridge rectifiers installed within the alternator that use four diodes to help convert AC to DC. The converted DC is then sent to the battery for storage.

How AC And DC Currents Are Converted

AC power can be converted to DC power through an electronic device called the solid-state diode which are of different types. Alternatively, an AC adapter can be converted to DC using a transformer or a rectifier combination.

A diode that produces chemical energy is a simple semi-circular device comprising two electrodes: the n-doped or p-doped silicon, with the cathode being the positive terminal. Two more electrodes are often used: one more positive than the cathode, and another less charged than the cathode making up for 3 terminals.

Cathodes are known as negative because of their voltage potential when compared to the ground (0 volts); they are not negative in any other respect. These cathodes and diodes are also applied in lithium-ion batteries. The battery always provides lower voltages for your car’s electrical system.

Symptoms Of A Bad Battery

Some several signs and symptoms should be enough to bring to your attention that your car battery is not working optimally as it should and needs an immediate check-up, repair, or even replacement. These symptoms include:

Slow Engine Crank

This can be easily noticed when you attempt to ignite your car and the cranking of the engine becomes very sluggish and takes longer than normal to start. This moment could better be described as a “rur rur rur” starting noise sound.

Check Engine Light

The check engine light will often illuminate when your battery power is too weak. These alarming system indicator lights like the check engine light and the coolant light could mean there is a problem with your battery or may point out a cooling system that is malfunctioning making the battery run hot.

Low Battery Fluid Levels

Car batteries always have a translucent casing. This is so because you are supposed to keep an eye on your batteries’ fluid levels. Fluid levels can also be inspected by opening the red and black caps if they are not permanently sealed, just in case your battery casing isn’t translucent. However, modern vehicles come with caps permanently sealed

If you notice that the fluid level is below the lead plates which are usually the energy conductors inside your battery, you need to have the battery and the charging system tested. A drop in fluid levels is a sign of overcharging or overheating.

Swelling Or Bloating Of Battery Case

Quite often you will see the casing of your battery bloated or swollen like it just taken some heavy meal. When you notice this with your battery, it is a clear sign that your battery isn’t in good shape. The main culprit contributing to deforming the attractive look of your battery casing is excessive heat that makes the battery casing bloat hence decreasing its efficiency and time.

Stinky Rotten Egg Smell

You may notice that your battery emits a pungent rotten egg smell that is normally associated with sulfur odor around your battery. A battery leak usually causes this pungent rotten egg smell.

When not addressed immediately it often leads to corrosion of the terminals where the (+) positive and the (–) negative connections are located. The battery may need to be replaced else the car may not even start.

3+ Years Battery Age

Ideally, your battery can last way beyond three years. However, this will mainly depend on your day-to-day driving habits, the weather and the frequent brief trips of less than 20 minutes can drastically shorten the lifespan of your car battery. When your battery goes beyond three years, at the very least you should have its condition inspected every year to determine if it still has the potential to perform efficiently.

Is Alternator Giving Battery Less Power?

As we had discussed early, a car battery plays an important role in providing power to the starter to help it ignite the engine. The battery also has to be charged constantly. This is done by an onboard alternator within the car. How will you know if your car’s alternator isn’t providing enough charging power to the battery?

  • The electrical system becomes “possessed”. In this case, the alarming flickering warning lights such as the check engine light begin to illuminate in a flashing manner. These symptoms of malfunction often start unfolding as a sign that the battery is completely drained and is struggling to provide the required amount of power. If the alternator becomes faulty, your battery will no longer receive power and your electrical system is just moments away from a total breakdown.
  • The slow crank; in this case, you try to start your car, and it keeps turning endlessly. This may eventually end in the car starting but after a very long time or not starting at all. This means that your alternator is faulty and isn’t properly charging your battery. When you begin to experience this, take a moment to visit your mechanic because it may mean you are not far from losing your battery and alternator.

The above symptoms are likely to start unfolding when the battery isn’t receiving enough power because the alternator has become faulty. The battery will keep on draining until the battery drains completely, and the car will stall. The sooner you will have your car inspected the better and the less likely you can face the driver’s biggest fear of the car failing to start.

Is Battery Too Old?

To determine if you’re your battery is too old, you can have a glimpse of the four or five digits date code on the cover of your battery casing. The first part of the code is very vital: look for the letter and digit.

A letter is assigned to each month like A may represent January, B for February and the sequence goes on. The number that follows refers to the year e.g. 9 for 2009 and 11 for 2011. The dates can help you decipher when the battery was shipped from the factory to the distributor.

The extra digits will tell where the battery was made. On the average car, batteries can last three to five years. Mind you, there are several weak battery signals that you can always look up to like a slow engine crank because of low fluid levels, a bloated or swollen casing of your battery, smelly rotten egg pungent that emanates from your battery, and your check engine lights illuminate.

If your battery has lived beyond three years and these signs begin unfolding, then it’s high time to make arrangements for a replacement.

Can A Bad Battery Harm The Charging System And The Starter?

The answer to this is a yes. When your battery becomes weak either through prolonged wear and tear or physical damage, your car will end up putting a lot of unnecessary stress on healthy parts. This will affect the charging system, starter motor, or starter solenoid.

These components can malfunction because they are drawing excessive voltage to compensate for the lack of battery power. Leaving this problem unsolved can lead to wearing out these components and you will have to face the expensive replacement or repair costs involved. Don’t leave your car’s power faults to chance, you may end up paying dearly for it.

Applications Of DC Power

DC electricity is used in several applications which include:

A DC battery is used to charge batteries, such as the car’s battery AC converter.

DC volts are often applied in electronic equipment that uses direct current for example televisions, radios, computers, and printers. The term “direct current” refers to the power that has a constant polarity.

Typically, a small AC supplies power to an electronic device; however, the electrical current inside of the device effectively converts the AC power into DC power by using diodes that block reversal of current flow and capacitors which store energy until enough voltage is available to drive a load.

Is A Car Battery AC Or DC

So, although the input for these electronics devices might be AC output mains voltage from your home’s electrical system, all direct current electronics devices use DC generators internally.

DC batteries are used in fluorescent lightings in office buildings or supermarkets. The large ballast seen at the base of every fluorescent light contains a bridge rectifier inside which enables AC power from an electrical system to be converted into direct current flows to charge up the large capacitors found there, and then that stored energy is released by discharging it into the cathodes of all of those little gas-filled tubes inside of every fluorescent light fixture.

DC voltage just flows one way, from high voltage down through a load such as an incandescent bulb to ground, unlike alternating current which changes direction periodically.

Is A Car Battery AC Or DC: Conclusion

If you have read this far, you have concluded that the battery is a very integral system of the entire electrical system of your car. Your burning question “is a car battery AC or DC” has effectively found concrete answers.

Yes, a car battery is a DC power output that helps power all DC electrical components in a car. There also exists other components that works in unison with the battery such as the alternator, AC converters, and rectifiers. It’s important to always inspect your car battery to ensure it’s free from faults mainly because if such faults are ignored they may develop into bigger and costly repairs or replacements.

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