Types of Batteries and their important Characteristics.

Batteries are accumulators that convert stored chemical energy into electrical energy and are an essential device in isolated, self-consumption installations.

Principle of Battery

The basic principle of a battery comprises the oxidation-reduction (redox) reactions of particular chemical substances. One chemical substance of which loses electrons (is oxidized) while the other gains electrons (is reduced), being able to return to its initial configuration.

What are batteries and cells?

A battery is also called an accumulator or cell. Batteries consist of chemical cells that have a positive pole called an anode and a negative pole cathode, as well as electrolytes that allow electrical flow to the outside.

It can convert the chemical energy inside them into electrical energy.

This electrical energy is direct current, as it travels from one part of the battery to another, or between the negative and positive poles.

These cells convert chemical energy into electricity, either a reversible or irreversible process depending on the type of battery.

There are two types of cells

1. Primary batteries
2. Secondary batteries

Primary Batteries

Those that, once the reaction occurred, cannot return to their original state. Thus depleting their ability to store electric current. Primary batteries are also popularly called “Non-rechargeable batteries.

For example batteries in wall clocks, radio, other portable equipment.

ALKALINE BATTERIES

The alkaline battery comprises the negative electrode is zinc and the positive electrode is manganese dioxide (MnO2). The electrolyte solution is potassium hydroxide.

Secondary batteries

It is, that can receive an application of electrical energy to restore its original chemical composition and can be used numerous times before being completely exhausted.

Secondary batteries are also called “Rechargeable batteries”.

Through charge and discharge cycles, batteries convert electrical energy into chemical energy (charge), and chemical energy into electrical energy during discharge. Therefore they are said to be batteries or rechargeable batteries.

Lead-acid batteries

As shown in the below figure, the Lead-acid battery consists of plates, a separator (insulating material), and electrolyte solution. It is of hard plastic, with a hard rubber case. The electrolyte is water and sulphuric acid. A 12 V battery means 2.1V per cell and 12 V is produced by cells.

Nickel batteries

They are further divided into Ni-Cd (Nickel-Cadmium), Ni-MH (Nickel-Metal Hydride).

Nickel Metal Hydride (Ni-MH) battery offers high energy density than Nickel Cadmium (Ni-Cd) battery. They store double the energy of Ni-Cd batteries.

Lithium-Ion batteries

They are heavy and prone to the memory effect. Li-ion batteries store the same energy as Ni-MH batteries and weigh less by 20 to 35 percent than Ni-MH.

Basics of batteries

Each type of battery one with different characteristics, different prices, and different purposes.

The development of batteries is close to the development of current technology.

Depending on the use, the batteries are manufactured with different sizes, powers, or voltages.

The charge capacity of a battery depends on the nature of the chemical elements that make it up and is ampere-hours (Ah).

Thus, for example, a 1Ah battery can deliver 1 amp of current in one continuous hour. The greater its load capacity, the greater the current it can store inside it.

Important Battery Characteristics

  1. The amount of energy batteries can store is denoted in Watt-hours (Wh).
  2. The maximum current they can deliver (discharge-in Ampere-hour (Ah) and capacity.
  3. The depth of discharge that can sustain percentage data (%) amount of energy they can store.

The amount of energy they can store is represented in Watt-hours (Wh)

The watt-hours (Wh) of a battery can be calculated by multiplying its nominal voltage (V), by the maximum current (Ah).

                 Wh = rated voltage X Ah

Maximum current they can deliver (Discharge)

The amp-hour (Ah) is a value that the battery manufacturers will give us and we will find it printed on the label that all the batteries have attached to the container. To obtain this value, the manufacturer subjects the battery to a discharge test at a constant current, the time it takes to form a 100% charge to a 20% charge is what will determine the Ah.

For example, a battery with a capacity (C) of 300 Ah

Discharge time (standard) = 20 hours

Current (during test) = 15 A

We have to know how to interpret this value in Ah a little since it is only a reference value to classify batteries and given the case, and taking the battery from the previous example, it could not deliver 300 A for one hour.

This would mean accelerating the electrochemical reaction and as consequence, the internal resistance of the battery would increase, which would result in a drop in the output voltage.

If, on the other hand, we had a discharge current lower than that specified, for example, 10A, the Ah ration would be fulfilled. The 300 Ah battery in the example could sustain this value for 30 hours.

Current as a fractional value

Manufacturers also give a discharge current a fractional value of its capacity in Ah, these values can be C/10, C/20, C/50, C/100, etc., this value represents the number of hours of discharge that a battery can be delivering the specified current (Ah), with a constant flow of energy. In our example, C/30 would represent 10A and C/60 would be 5A.

It is advisable, in isolated installations, to buy a battery that would give us a capacity of C/100 with the consumption that we have or want to give to our installation. This way we would insure 3-4 days of electricity in case the weather conditions did not allow us to generate it.

Discharge depth

The depth of discharge is a percentage value (%), which represents the amount of energy that we can extract from the battery. To know this value, we must calculate the Watt-hours (Wh) of the battery, then based on the energy delivered, we determine the percentage (%).

For example, if the battery was 300 Ah and 12 V

12 V X 300 Ah = 3600 Wh

If 1800 Wh has been consumed the depth of discharge is 50% battery is self-discharge.

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