UniEnergy Technologies » Capacitor vs. Battery: What Is The Difference?

Capacitor vs. Battery: What Is The Difference?

A capacitor is a passive device that offers energy or power to the circuit, while a battery is an active component. The capacitor and battery are both energy-storing gadgets but with different ways of holding the energy. The capacitor utilizes the electric field to store the energy, while the battery uses chemical reactions for the same purpose. The voltage across a capacitor decreases when operating while the battery’s voltage remains unchanged but reduces when its discharged.

A battery is a chemical compound that holds the energy in the electrochemical cells. While capacitors are chemical compounds that store energy, they don’t keep as much charge as the battery.

In this post, we’ll explain the difference between batteries and capacitors, how they are used, their main differences, and their features.

What is a capacitor?

What is a capacitor

A capacitor is a device that keeps electrostatic power in an electric field between two places. It’s a passive part of your circuit that comprises more than two plates. The dielectric medium fills the void between the plates. They’re capable of releasing energy faster.

The capacitor’s efficiency can go past 98%, and this is because there’s no conversion of power in another form involved. Power is absorbed as electrical energy, and when needed, it’s obtained in the form of electrical energy.

Capacitors are available in various types, such as Electrolytic, mica, plastic plate, tantalum, and ceramic.

The capacitor has conducting plates that are separated by dielectrics. When the electric current flows to the capacitor, it enters the plates, and the dielectric interrupts the current flow, and a charge accumulates. The energy is held with the electric field in the plates. The voltage across capacitors is variable and will depend on the amount of charge available on the plates.

In analysis, a capacitor is considered an insulator for direct current(DC) and conducting component for alternating current(AC). So, it’s used as a DC-blocking component in most circuit designs. The capacitor’s capacitance is known as the ability to keep a charge. It’s measured in farad (f) units.

What is a Battery?

What is a Battery

A battery is utilized as a source of energy in electrical circuits. A battery usually offers a constant potential difference(volts) between two terminals and supplies a direct current (DC). The possible difference the battery offers is called its electromotive force, measured in volts (V). So, the batteries are DC components. Nevertheless, DC-supplying batteries will be transformed into AC using a circuit known as an inverter. So, batteries with in-built inverters are available.

Batteries are available in different types, such as lithium-ion, Alkaline, zinc-carbon, and lead acid.

Power is stored inside the batteries in the form of chemical energy. It transforms into electrical energy when operating. When the battery is connected to the circuit, a current emits from the anode (positive electrode), travels via the circuit, and then returns to the cathode (negative electrode). This is also recharged. So, some batteries aren’t rechargeable and need to be replaced with the same model.

Since energy is used in charging and discharging the battery to perform chemical reactions, the usable energy is below the energy used in charging. So, the conversion efficiency is below 90%. The conversion efficiency for lithium-ion batteries is 80 percent, and that of lead-acid batteries is 65%.

Capacitor vs. Battery: Which is Better?

Capacitor vs. Battery: Which is Better

A capacitor is a gadget that holds energy in the electric field. It’s used in electronic circuits and power units to control current flow and store power. On the other hand, a battery is a gadget that transforms chemical energy into an electrical charge. It comprises electrodes, an electrolyte, and an insulating substance separating the two electrodes. A battery’s voltage relies on its SOC (state of charge).

Capacitors are better than batteries since they have a longer life cycle and can keep more power per unit volume than the batteries can store. Capacitors are also better than batteries since they have lesser internal resistance. This means they offer more power at any voltage level.

A few years back, engineers designed a component known as a supercapacitor. It’s a battery and capacitor hybrid, and it can store more power than ordinary capacitors.

Capacitor vs. Battery: The Differences

While capacitors and batteries are used to keep an electrical charge, they’re very different. However, they both serve as a source of energy. Capacitors have many essential properties which make them useful as the best power source.

1. Basic parts

As an electrical gadget, a battery contains two electrodes (negative and positive) separated by the electrolyte. On the other hand, capacitors contain two metal plates with a dielectric material.

2. Terminals

Many rechargeable batteries have negative and positive terminals. When the battery is charged, the terminals aren’t connected; hence, no direct current flows through the circuit. After the terminals are connected, the constant current will flow via the circuit until the battery attains 100% of its maximum capacity.

Capacitors don’t have negative and positive terminals. Instead, they have two electrical terminals divided by a thin insulator known as a dielectric. This insulator has a higher resistance. When the terminals are attached, the current stays constant till the capacitor is discharged. For this reason, a smaller current flows via the capacitor when it’s initially recharged.

3. Discharge and charge rate

Discharge and charge rate

Capacitors have a higher discharge and charge rate than batteries. That’s why they’re used as a battery substitute when you want to make regular power surges. The benefit of using a capacitor is that it won’t lose its charge with time and can be used for many hours without recharging. On the other hand, batteries lose their charge with time and must be replaced.

4. Application

Capacitors tend to be perfect for higher frequency uses such as radios since they can handle higher voltage applications. On the other hand, batteries are perfect for keeping larger amounts of electrical power, such as in flashlights, since they can withstand larger current drains.

5. Internal resistant

The capacitor has a low internal resistance, making them instantly deliver energy. Batteries, on the other hand, have high internal resistance. That means they take longer to deliver power. That’s why they’re always used as auxiliary energy sources for flashlights and electronic devices.

6. Polarity

Polarity is the -ve (minus) and +ve (plus) signs of electrical devices. For instance, a battery features negative and positive ends. The battery’s positive terminal connects to the positive tip of the other components in the circuit. The battery’s negative terminal connects to the circuit’s negative part of the other parts.

Capacitors don’t have negative or positive ends. Instead, they feature two plates separated by a dielectric. When one connects a capacitor between the negative and positive terminals of the circuit, it becomes polarized. The capacitor will hold the charge when polarized even after turning off the power. That means even if you remove the capacitor from the positive end of the battery, there will be a smaller amount of residual electricity remaining in the capacitor.

In contrast, batteries lose their polarization when the power source is cut off. That means if you remove the cap from the positive end, there won’t be any remaining power in the capacitor.

Compared (Cost, Features)

Now, let’s look at the features of the capacitor and battery.

  • Type of electrical component: A battery is an active component of the circuit, while the capacitor is the passive component.
  • Voltage: The voltage across the battery’s terminals remains constant. On the other hand, the capacitor voltage is variable and directly proportional to the energy amount or charge available on the plates.
  • Energy density: The battery’s energy density is high, which means a higher amount of energy can be held in a smaller volume. The capacitor’s energy density is lower.
  • Discharging or charging rate: The battery’s charging and discharging rates are slow since chemical energy is transformed into electrical energy. The capacitor’s charging or discharging rates are faster since energy is held on the plates.
  • Usage: Batteries are used as DC components, while capacitors are used for AC applications. Their work is to block DC components from your circuit.
  • Polarity: When charging the battery, the circuit’s polarity should be the reserve of what it is when discharging. The capacitor’s polarity remains unchanged when charging or discharging the capacitor.
  • Price: A single-stage AC capacitor can cost $10-$50, while the dual-stage AC capacitor starts at $20 and can go up to $200. A start capacitor runs as required and can cost between $10-$180. That means a capacitor is more expensive than a battery.


You don’t have to pick one device over the other. These two devices do a perfect job at what they’re created for. Typically, capacitors are preferred over batteries when one needs a faster charge. On the other hand, batteries are preferred when you want to prolong your device’s lifespan. So, the decision depends on your preference and needs. You only need to know which is ideal for you and your gadget. Feel free to comment if you have any questions or concerns.

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