Make Your Own
Step 1: INTRODUCTION
As we all deal with various potential battery e.g 3.7v li-po li-ion battery, 6v 9v, 12v, 24v lead acid battery. It can be charged using its respected chargers but if we want to monitor charge status then we have to buy different indicator module for Different batteries ,we need to do something for that, Guys we can make your own that can measure charge level of all battery types.
Step 2: Resistors
We have to use couple of resistors in this project, you can use 4 band(+-5%) resistor but 1% give you good results. Use 10turn pot instead of 1 turn for better results.
Step 3: Referance Voltage Source
We need a precision Refrance voltage for LM339 Quad Comparator IC. we can use cheap but accurate LM336 it has minimum referance voltage if 2.09v as TL431 has 2.5v , using LM336 give you best result.
Step 4: LM339 (Quad Comparator IC)
LM339 is a quad comparator IC , It has four Independant Comparators.
Step 5: Schematic Diagram
Use Those Diagrams to make your Own.
Working:- Working of these module is simple LM339 Variable Shunt Regulator Provide 2.09v of Min Ref voltage this Ref voltage is now Divided into some Parts using Divider Network of four resistor 2.09v, 1.56v, 1.04v,0.52v as shown in circuit diagram for four Comparators at non-inv input, Inverting input is connected to 10k (10 turn) Pot , voltage at inverting input can be adjusted by pots,
When voltage of inverting input increases (as increase of Batt. Voltage) Output of Comparator pulled LOW Finally Light turns ON,
Step 6: All Done
Make Your Own , If you have any trouble You can Ask Questions.