Battery level indicator

                                                   Battery level indector

Description

Here is a easy to build low battery level indicator circuit that produces a visible indication by flashing a LED when the battery voltage drops below a predetermined voltage.The circuit is based on Panasonic’s  IC MN13811G   and a efficient flasher based on transistors Q1&Q2.Here when the battery voltage drops below 2.4  V the output of the IC is activated and the flasher starts flashing.This circuit here is an ideal one for monitoring the level of all types of 3V batteries.The circuit is power efficient with a  idle current drawing as less as 1 uA  , and a current drawing while flashing as less as 20uA.

Circuit Diagram :

Parts List

3 volt Battery

100F - capacitor

ICI  -MNI13811 

R1 4.7 M

0.68 F Capacitor

R4 -680 Ohm

BC558 

 R34.7 k

BC548

R410K

5-100 OHM

 LED -Green

Notes.

Assemble the circuit on a good quality PCB or common board.

Do not keep the soldering iron tip on the IC’s pins for long time.

IC MN13811  series are available with different trip point voltages( from 2.4V t0 4.8V) ie MN13811G to MN13811U .If you need a trip point other than 2.4 shown here, you can choose the corresponding IC from the data sheet  and use it in the circuit here.