Easy Way to Check 18650 Battery Capacity

About: Undergraduate , like to make new thing ,circuits and like to share my knowledge with others.

This is a simple method for you to check your 18650 battery capacity.

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Step 1: You Need

18650 charging module ( TP 4056 )

USB female port

18650 battery holder

USB doctor

USB loader

Step 2: Connecting

connect USB female port, battery holder and charging module like the photo.

Step 3: How to Measure Capacity

1. first, you put in the battery to the holder and connect USB loader.

2. after battery full discharge remove loader and connect to the charger and wait to fully charge.

3. after the complete charging process remove the charger and connect USB doctor.

( USB doctor display must be zero if it is not reset using push switch )

4. then connect USB loader to USB doctor.

5. wait to finish the process.

6. check your battery capacity.

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    3 Discussions


    7 weeks ago

    A couple of questions:
    1) What is a "USB loader" ? Is this a controlled discharging device ?

    2) At what voltage is the Li-Ion cell considered fully discharged ?
    (Over-discharge will damage the cell, so this information is crucial.)

    And just to mention, because of the laws of physics, the total charge taken by the Li-Ion cell will be slightly greater than the charge you can take from it.
    (A cell is less than totally efficient.)

    1 reply
    shelter techElectroFrank

    Reply 5 weeks ago

    1. USB loader basically uses for check current and in this tutorial, we use for discharge battery. USB doctor calculates Voltage & current USB loader used.
    2. TP 4056 charging module used for Overcharging Protect, Over-discharge Protect And short circuit protect. So we Don't need any extra protection.