Lead Acid Battery

Despite having a small energy-to-volume ratio and a very low energy-to-weight ratio, the cells’ ability to supply high surge contents reveals that they have a relatively large power-to-weight ratio compared to other types of batteries.

Batteries made of lead-acid can be classified as secondary or auxiliary batteries Secondarily, the chemical reactions that take place in secondary cells are completely reversible.

By passing current through the battery, the reactants that generate an electric current in these batteries (via chemical reactions) can be regenerated (recharging).

Diffusing current from a secondary battery (forward reaction) is accomplished through a chemical process known as discharging.

Charging is the term used to describe the process of regenerating active material.

Battery with a Sealed Lead Acid Cell

The sealed lead-acid battery is made up of six cells that are stacked one on top of the other in a single case.

The cells are connected in series, and each 2.0V cell contributes to the battery’s overall 12.0V capacity by adding together.

Despite the fact that they are relatively heavy, lead-acid batteries are still preferred over other lightweight alternatives due to their ability to deliver large amounts of electricity in a short period of time (which is required to start a cold engine in an automobile).

Lead-acid batteries are made up of a stack of alternating lead oxide electrodes that are separated from one another by layers of porous separators. When fully charged, the electrodes are separated by a porous separator.

Every one of these components is immersed in a highly concentrated solution of sulfuric acid. Since the intercell connectors connect the positive end of one cell to the negative end of the next cell, the cells are arranged in series, as shown.

Chemical Reaction for the Purpose of Discharging

When the battery is discharged, it acts as a galvanic cell, causing the chemical reaction described below to occur.

Negative:

The reaction Pb(s) + HSO₄ + H₂O(l) is equivalent to the reaction 2e + PbSO₄(s) + H₃O(aq) (oxidation )

Both electrodes produce lead sulphate, which is toxic.

During the course of the reaction, two electrons are also transferred.

The corrosive sulphuric acid in the lead acid battery is contained within a thick rubber or plastic case to prevent leakage of the acid.

How to Charge a Lead Acid Battery

Because of the decomposition of the sulphuric acid present in the lead discharge battery, it is necessary to replace it.

Occasionally, the plates will change their structure on their own accord.

When the battery begins to lose its effectiveness, it should either be recharged or replaced.

When automobile batteries are left in their discharged states for extended periods of time, the lead sulphate buildup can become extremely difficult to remove.

This is why lead-acid batteries must be charged as soon as possible after being discharged (to prevent building up of lead sulphate).

Charging of lead batteries is typically accomplished by connecting them to an external current source.

A plug is inserted and connected to the lead-acid battery, causing the chemical reaction to proceed in the opposite direction of the original direction.

When the sulphuric acid in the battery (or some other component of the battery) has decomposed, the charging process may become inefficient as a result of the degradation.

As a result, it is recommended that you check the battery on a regular basis.

Chemical Reaction for the Purpose of Recharging

The chemical reaction that takes place when a lead-acid battery is recharged is detailed in the following section.

Negative:

2e + PbSO₄(s) + H₃O +(aq) –> Pb(s) + HSO₄ + H₂O(l) 2e + PbSO₄(s) + H₃O+(aq) (reduction)

Positive:

In the presence of 5H₂O(l), PbSO₄(s) becomes PbO₂(s) + HSO₄(aq) + 3H₃O +(aq) + 2e (oxidation)

When the automobile battery is being recharged, it behaves similarly to an electrolytic cell.

In order to drive the recharging, energy must be obtained from an external source, such as the engine of a car.

The formation of by-products such as hydrogen gas and oxygen gas can also occur as a result of overcharging the battery, which should be taken into consideration.

These gases have a tendency to escape from the battery, resulting in a reduction in the amount of reactants available.

What to look for when determining whether a battery is lead acid

The following are the two methods for determining what type of battery you have:-

Using the first method, you’ll need to look at the label on the battery.

Among the terms you’ll come across when searching for liquid batteries or flood-lead-acid batteries are  wet cell,     lead-acid,   or   flooded lead acid,   and   liquid lead acid.

Gel-filled lead-acid type batteries will now be identified on the label by the words   Gel-Filled.

The AGM lead-acid batteries’ labels should state   AGM   or, in full words, Absorbed Glass Mat,   as well as terms such as   dry cell,     sealed regulated valve,     non-spill,   or   regulated valve   on the label.

The second method entails taking a look at the battery’s top section.

In most cases, batteries have removable tops or caps, unless the battery is labelled as   sealed,   which indicates that it is a liquid lead-acid battery.

Battery tops on gel-filled and AGM lead-acid batteries are flat, and it is from these flat tops that the positive and negative endpoints protrude.

This method necessitates the use of safety equipment (such as safety goggles and rubber gloves) due to the need to shake the battery.

After a heavy shake, you’ll notice that the type of liquid lead-acid battery you’re using has a wiggle.

It is common for the liquid centre to continue to move for a period of time after the battery has been sealed.

It is in fact the polar opposite.

Gel-filled batteries and AGM lead-acid batteries will not wiggle after being shaken, so be sure to check before using them.

Conclusion

Invented in 1859 by French physicist Gaston Planté, the lead–acid battery is a type of rechargeable battery that can be recharged multiple times.

Historically, it is the first type of rechargeable battery to have been developed.

The energy density of lead–acid batteries is lower than that of modern rechargeable batteries, which is a disadvantage.

Despite this, the cells’ ability to deliver high surge currents results in a power-to-weight ratio that is relatively high compared to their size.

The combination of these characteristics, as well as their low cost, make them particularly appealing for use in motor vehicles to supply the high current required by starter motors.