Cell Capacity tester

A device which tests the capacity of various rechargeable cell chemistries.

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Cell capacity tester, originally designed and programmed by Debasish Dutta, this handy dandy little project allows you to test the capacity in mAh of various cell chemistries. I found this project on instructables under the user "open green energy" and decided to build it with my own modifications. Even though it is not a project i came up with on my own, i decided to share it anyway as many people like to add their own unique flavor.

i used what components i had available, some not the most ideal choice such as the the mje3055t transistor used for the load switch, a mosfet would have been a better choice, regardless, it is still fairly accurate.

It is technically a finished unit but i intend to eventually add charging and balancing functions to it in addition to handling multiple cells, there for it is listed as "ongoing".

BCM Video.mp4

Video of the unit functioning.

MPEG-4 Video - 8.82 MB - 02/22/2019 at 14:05


ms-xpsdocument - 249.66 kB - 02/22/2019 at 13:57



Arduino Sketch for Cell capacity meter

ino - 9.26 kB - 02/22/2019 at 13:42


  • 1 × Project Box In my case, a microscope slide box was perfect.
  • 1 × Arduino Nano
  • 1 × piezoelectric buzzer for audio indication. get creative and make it play a tune when it is done testing..
  • 2 × alligator clips just what i used
  • 2 × magnets 52N rare earth, 1cm diameter.

View all 13 components

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Bonez wrote 09/19/2019 at 14:30 point

i actually have come to use  regularly as is but raised the resistance to 10 ohm instead, i have tested about 200 lithium ion cells reclaimed from laptop battery packs  so far and found it to be very accurate, within 50mah tested against a professional made capacity tester.

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Bonez wrote 02/26/2019 at 20:12 point

well, it is pretty accurate as is for lithium ion and LiPo, but in hinde sight, i should have and probably will set the 2n3055t transistor to a PWM pin to act as a variable resistor and change the code to adjust down the resistance to 100ma for NiCd and NiMH cells, 5 ohm is too heavy a load for some cells to get an accurate measurement of capacity, or possibly set it to read the voltage drop for a given resistance and make it self adjust, but im learning!

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Alexander wrote 02/26/2019 at 07:54 point

Neat build! Perhaps include a link to the original Instructable? I would love to see more information about the changes you made, as well as demonstrations of it measuring various cell chemistries. Does it seem to be accurate? What types have you tested on it so far?

Cheers and good work!

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