Question

I have a Li-ion cell I need to measure the cell voltage which is unknown. you need to measure the voltage of the battery. You can design the circuit which measures voltage. I need a circuit diagram with explanation. don't say use voltmeter instead you can draw an internal diagram of how it is working.....

Answer 1

INTRODUCTION:

A Voltmeter is a measuring instrument which measures the voltage between the two nodes in an electric circuit. In analog voltmeters the pointer moves across a scale in proportional to the voltage of the circuit. Digital voltmeters have a numerical display of voltage by using an analog to digital converter.

To measure the cell voltage we connect the cell across the Voltmeter and according to its value Voltmeter show it's potential.

Working:

Its Working is based on the principle of Ohm’s law. Ohm’s law states that – “Voltage across a resistance is directly proportional to the current passing through it”. Any basic meter has a potential difference across its terminals when a full-scale current flows through it. The symbol to represent the voltmeter is a circle with an enclose

Its Working is based on the principle of Ohm’s law. Ohm’s law states that – “Voltage across a resistance is directly proportional to the current passing through it”. Any basic meter has a potential difference across its terminals when a full-scale current flows through it. The symbol to represent the voltmeter is a circle with an enclosed letter V.

Fig. 1– Circuit Diagram to Represent Voltage(Internal Circuit Diagram)

A voltmeter is always connected in parallel to the component in a circuit for which the voltage is to be measured. A DC volt-meter has polarity signs on it. Therefore one has to connect the plus (+) terminal of the volt-meter to the higher point of potential and the minus (-) terminal to the lower point of potential in order to obtain a meter deflection.

Similarly, for measuring cell we connect across the Voltmeter as shown in the above fig 1.