Lithium Battery Capacity Tester





Introduction: Lithium Battery Capacity Tester

Hey! everyone My name is Steve .

Today i'm going to show you How to Test Lithium Battery Capacity .

Couple of weeks back i took 18650 Battery from an Old Laptop Battery

I don't know the current Capacity of these batteries So i did this test to find out how much capacity is left

Click Here to See The Video

Let's Start

Step 1: Stuff I Used

  • Lithium Battery Capacity Tester click
  • 18650 Lithium Battery (Test Subject)

Lithium Battery Capacity Tester

  • It's Supplyed with 2 7.5 ohms 5W resistance
  • it can take input up to 15V and 3 Amps


  • Fully adjustable according to your need
  • very cheep price

Step 2: Connection

You can see the label over the board

+ Connects to Battery positive

- Connects to Battery negative

R Connects to Resistance (Load )

R Connects to Resistance (Load )

You need a wall adapter or a power bank to power the Module

Step 3: Attention !

Make Sure Your Test Battery are Fully Charged

*Otherwise the result will be less then what it is capable up to

Step 4: Configuration

All things are connected Now you are good to go

  • you can see "-" and "+" button are there you can set the cut off voltage from there (For example - Lithium battery the cut off voltage will be 3v )
  • Now hit "Ok" button to start the test

It will take 2-3 hours to test (time is depending upon the batteries )

Step 5: Result

After 3 hours of test i got 1246mAh of capacity left in my old 18650 battery

Happy to see that

Thank you for visiting my Instructables


  • AshwinC6 made it!


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Questions & Answers


I made it! I connected both resistors in parallel to make the test faster. Or did I do something wrong?

it's good but use only 1 resistor because when you will do test with 1 resistor you get the accurate capacity " it's little hard to explain but it's all about C rating or Discharge rate " " and internal resistance of the battery "