Demystifying battery terminology

They usually work fine when they are new, but as the car ages; the battery is subjected to wear and tear too and may need eventual replacement. Failure to do so may sometimes leave you stranded by the side of the road.
The replacement batteries need to be as good as the one your car came with, and if you want reliability purchasing the right battery is a must.
Ideally, you should buy the battery that closely resembles the original at least in physical size, or you may be buying yourself endless grief.
Modern batteries have different sizes, have different terminals, and have terminals in different locations and so on.
To better equip you in making the best battery choice for your car, take time to familiarise with some of the technical terms that you will tend to find on the label of the battery as an indicator of its performance potential and structure.
Ampere (A) — This is the unit of measure of the flow of the amount of current flowing through an electrical circuit
Amp Hour (Ah) — This is the unit of measure for a battery’s electrical storage capacity obtained from multiplying the current in amps by the time in hours of discharge. For instance, A battery rated as having a capacity of 20Ah can supply a current of 20 A for 1 hour or 10A for 2 hours.
Discharging — When a battery is delivering power, it is said to be in a state of discharge.
Capacity — The ability of a fully charged battery to deliver a specified quantity of electricity at a given rate (Amperes) over a definite period of time. Battery capacity is dependent on the construction, materials, size, weight, temperature and age of the chemically active materials in the battery.
Cranking Capacity (CC) — The principal function of the battery is to provide the energy required to crank the engine during starting.
This requires a large discharge in a short time. The cranking capacity in Amps specifies the current to which a new, fully charged battery is capable of delivering for six minutes before the voltage falls to 7,98 volts (1,33 volts per cell) at 25 ° Celsius.
Reserve Capacity (RC) — In the event of the charging system failing the battery may be required to provide electrical power to enable the vehicle to be driven for a short distance.
The reserve capacity gives an indication of the battery’s ability to supply the minimum load under the worst conditions.
This could require current for ignition, low beam lights, and windscreen wipers and demisting. Numerically, the RC can be further summarised as the time which a new fully charged battery can deliver 25 Amps continuously before the voltage falls to 10,5 volts (1,75 volts per cell) at 25°C
Cold cranking capacity also known as cold cranking Amps (CCA) — The primary function of a battery is to start the engine. This is accomplished by rotating the crankshaft (cranking) and providing the electrical power required to activate the ignition system until the engine fires and starts.
This requires high current over a short time. Because the current requirement is high when the engine is cold and the battery has less power when it is cold, the cranking capacity is defined as the output in amperes that a battery can deliver for 30 seconds while maintaining the voltage above 7,2 volts at — 18°C.
Most car batteries typically have a CCA rating in the order of 270-700. Diesel engines typically require 200 percent to 300 percent  more current than petrol engines. Unless you care to familiarise yourself with some of the technical terms on this page so that you can understand the label on the battery, the length of the battery guarantee is the best indicator of battery quality and reliability, traits that your Exide brand of batteries continue to meet with confidence over the widest range of battery sizes. Bear in mind though that if your car won’t start in the morning, it may not be the battery’s fault.
Before you replace it get your vehicle charging system checked by an expert. This may not be too expensive and could save you the cost of needlessly replacing the battery.