INTRODUCTION TO BATTERIES
An electrical battery is one or more electrochemical cells that convert stored chemical energy into electrical energy. Since the invention of the first battery in 1800 by Alessandro Volta, batteries have become a common power source for many household and industrial applications. Batteries are represented symbolically as follows
Fig. 1(a) Symbolic view Fig.1(b)conventional battery Electrons flow from the negative terminal towards the positive terminal. Based on the rechargeable nature batteries are classified as a. Non rechargeable or primary cells
b. Rechargeable or secondary cells
Based on the size they are classified as
a. Miniature batteries
b. Industrial batteries
Based on nature of electrolyte
a. Dry cell
b. Wet cell
1.1 Terminologies :
1.1.1 Accumulator - A rechargeable battery or cell
1.1.2 Ampere-Hour Capacity - The number of ampere-hours which can be delivered by a battery on a single discharge.
1.1.3 Anode - During discharge, the negative electrode of the cell is the anode. During charge, that reverses and the positive electrode of the cell is the anode. The anode gives up electrons to the load circuit and dissolves into the electrolyte.
1.1.4 Battery Capacity - The electric output of a cell or battery on a service test delivered before the cell reaches a specified final electrical condition and may be expressed in ampere-hours, watt- hours, or similar units. The capacity in watt-hours is equal to the capacity in ampere-hours multiplied by the battery voltage.
1.1.5 Cutoff Voltage final - The prescribed lower-limit voltage at which battery discharge is considered complete. The cutoff or final voltage is usually chosen so that the maximum useful capacity of the battery is realized.
1.1.6 C - Used to signify a charge or discharge rate equal to the capacity of a battery divided by 1 hour. Thus C for a 1600 mAh battery would be 1.6 A, C/5 for the same battery would be 320 mA and C/10 would be 160 mA.
1.1.7 Capacity - The capacity of a battery is a measure of the amount of energy that it can deliver in a single discharge. Battery capacity is normally listed as amp-hours (or milli amp-hours) or as watt-hours.
1.1.8 Cathode - Is an electrode that, in effect, oxidizes the anode or absorbs the electrons. During discharge, the positive electrode of a voltaic cell is the cathode. When charging, that reverses and the negative electrode of the cell is the cathode.
1.1.9 Cycle - One sequence of charge and discharge.
1.1.10 Cycle Life - For rechargeable batteries, the total number of charge/discharge cycles the cell can sustain before its capacity is significantly reduced. End of life is usually considered to be reached when the cell or battery delivers only 80% of rated ampere- hour capacity.
1.1.11 Electrochemical Couple - The system of active materials within a cell that provides electrical energy storage through an electrochemical reaction. 1.1.12 Electrode - An electrical conductor through which an electric current enters or leaves a conducting medium
1.1.13 Electrolyte - A chemical compound which, when fused or dissolved in certain solvents, usually water, will conduct an electric current.
1.1.14 Internal Resistance - The resistance to the flow of an electric current within the cell or battery.
1.1.15 Open-Circuit Voltage - The difference in potential between the terminals of a cell when the circuit is open (i.e., a no-load condition).
1.1.16 Voltage, cutoff - Voltage at the end of useful discharge. (See Voltage, end-point.)
1.1.17 Voltage, end-point - Cell voltage below which the connected equipment will not operate or below which operation is not recommended. 1.2 Principal of Operation of cell
A battery is a device that converts chemical energy directly to electrical energy. It consists of a number of voltaic cells....