1.0 Introduction
1.1 Project Overview
Battery level indicator is a circuit that is used to check the battery life. We can easily recognize the battery level with the help of LED's. It uses a LM3914 driver IC use to drive 10 leds by passing through it sufficient amount of current. Brightness of leds are controlled by reference adjustable pin and reference out pin. A variable resistor is also deployed in the circuit to have variable input voltage at pin 5 of the driver IC. Since the driver IC has two modes of operation which is bar graph mode and dot mode, it enables us to have indication of the battery life either in bar form or in dot form.
We can have coloured lods to indicate state of the batteries like first three leds will indicate low battery. Green leds will indicate full battery. Thus by using various coloured leds representation of battery life will be made easy to understand. Cascading the driver ICs we can increase the range of battery input in terms of voltage. in the below given block diagram we have 4 blocks. One is the power supply. other is the driver IC itself. We will have a led block and an input block. A reference input for comparison purpose. Leds will glow according to the input given and the reference Input present.
Power supply is ranging around 12 to 18V. Reference voltage is pre decided which is 1.25mV. Any dc signal lying in the range of the power supply is judged and the level is indicated by the leds. The current through the leds is controlled by the internal adjustment.
The battery level indicator consists of very less component and thus occupies very little space of the surrounding. Since only DC input voltage levels are indicated, components which work in AC supply can be used to detect AC levels. Since AC voltage having continuously varying amplitudes the leds will turn ON and OFF continuously making a good looking pattern. Thus our battery level indicator can be used for decoration purpose also.
1.2 Advantages
- A battery level indicator is with electronic appliances to arrange as to display, on an indicator, a real time voltage detected by voltage indicator.
- Indicator indicates how much power the battery will be able to supply to electronic apparatus.
- It is used to check the battery level with the help of LED's for example if three LED's, indicates battery capacity of 30 percent. And if 10 LED's glow then it is 100 percent.
- Easily indicate the battery level
- Enhanced version of this circuitry is the present mobile phone battery level indication system
- This circuit can be used in household applications like INVERTER. This circuit connected to inverter can help the users to know when to charge and when to leave the inverter idle
- Minimized version of this circuit can be also used for automobiles to indicate the battery level and low cost.
1.3 Disadvantages
- In case of voltage matching, correct level wouldn't be indicated
- 1f input voltage is higher than the calibrated voltage, for full scale input error will be shown.
1.4 Scope of Study
This project can be further extended in a useful manner, The basic design of battery level indication using single IC LM39 14 can be further improved by adding display control function and alert mechanisms to enable the easy knowing of the battery level. Instead of using the LED'S and LED controller in this circuit using a microcontroller can enable battery level indication as in mobile phones.
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