“I had bought few 9800 and few 4200 mAh lithium ion batteries from Aliexpress last year. They were quite cheap… and as I researched more on them, I found that these are fake and their actual capacity may be very less. Then I extracted Lithium ion batteries from old laptop battery. But wondered are these still at original capacity or have reduced their capacity. For a beginner DIYer it is difficult to buy expensive testers…. So, in this instructable, I will share how to make 1s lithium ion battery capacity tester”