Why batteries cannot be directly charged by AC?

What is AC?

Alternating Current is referred to as AC. The current constantly changes directions over a second. It can appear as a sine wave, square, triangular, sawtooth, & so on.

AC (alternating current) refers to more than just current. Electrical signals like voltage & power are also described using it.

Electric current & voltage in an AC circuit alternate between the positive and negative sides of their waveforms.

Periodically, alternating voltage & current run through a cycle (from positive to negative).

Frequency refers to the quantity of cycles made in a second.

As a result, alternating current travels from a positive half-cycle to a negative half-cycle, then back to a positive half-cycle, and so on. In simple terms, AC flows in one direction during one half of the cycle and in the other way during the other. For this reason, alternating current (AC) is also known as bidirectional current.

Note: Alternating current (AC) is a type of electricity that changes direction repeatedly per second. Because it occasionally flows in both directions, it is known as bidirectional. The number of cycles Alternating Current (AC) makes in a second is known as its frequency.

What is a DC?

Direct current is referred to as DC. The positive & negative sides of the waveform are not alternated by the current or voltage in a DC circuit. It does not go to the other side of waveform like in AC.

There is no frequency in a DC circuit.

Thus, current flows in a single direction in a DC circuit. The term “unidirectional” refers to this. Furthermore, a DC has a frequency of zero frequency (0 Hz).

What are Batteries?

A battery is basically an energy storage device used to store the electrical energy. It stores chemical energy in place of electrical energy. This chemical energy is capable of being converted to electrical energy.

Chemical energy is converted into electrical energy and stored in a battery. It consists of a cell or cells & two electrodes (Anode & Cathode).

Batteries are available in numerous sizes and capacities.

However, there are two points should know: All batteries consist of at least one connected cell with two electrodes.

One electrode is the anode (negative polarity) and the other is the cathode (positive polarity).

When a battery is a sourcing (discharging), conventional current passes through the battery via the anode (positive terminal) and exits through the cathode (positive terminal).

However, when a battery is used to sinking (Charging), conventional current passes through via the cathode (positive terminal) and exits via the anode (negative terminal).

How Does DC Charge a Battery?

To connect a DC source to a rechargeable battery, connect the positive terminal of the DC source to the positive terminal of a battery and the negative terminal of the DC source to the negative terminal of a battery. This completes the circuit.

The conventional current passes through the battery through the battery’s cathode. As a result, the battery is charged. Because the polarity of a (DC-Direct Current) remains constant, it continues to charge and unidirectional.

Why batteries cannot be directly charged by AC?

A battery does not directly store electrical energy. The battery holds chemical energy that is converted to electrical energy. The reasons why AC cannot be utilised to recharge a battery.

Consider that an alternating current (AC) source is directly linked to the rechargeable battery, with the positive terminal of the source connected to the battery’s positive terminal and the negative terminal of the source attached to the battery’s negative terminal. The flow of the current starts. However, a problem emerges.

The polarity of alternating current (AC), which flows in two directions, fluctuates. That is, current flows in one direction during one half of the AC waveform’s cycle, while it flows in opposite direction during other half.

The battery is charged by receiving regular current through the cathode during positive half cycle of the AC. The battery is discharged as a result of the current direction switching when the AC reaches the negative half cycle.

The AC’s positive half cycle, which charges the battery, subsequently terminates with the negative half cycle, which discharges the battery. The battery thus does not receive a charge.

In practise, if the battery is kept supplied by the Alternating Current (AC), it might be harmed.

The battery connections would need to be replaced when the AC switches between the positive and negative half cycles in order to prevent the drain of the battery brought on by negative half cycle of the AC. In simple terms, the battery connections would need to adjust to the AC’s variations. The frequency for this will need to be identical to that of the AC.

Therefore, AC cannot directly charge a battery since it alters the direction of its flow, causing a battery to be charged and discharged.