Introduction: Universal Battery Charge Indicator 3.7v-24v

About: I am a electronics hobbyist from india. Youcan visit my youtube channel "AviPrink" for more detailed information.

Make Your Own


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.