Hi,
I am new in this forum. I am trying to make a li ion battery capacity tester with charger. like this "HTRC B6 V2 80W 6A Digital RC Battery Balance Charger Discharger for LiPo Battery" but only for one cell i need at least 5 of them for testing 18650 cells i want to use multiple resistors and mosfets per discharger for keeping the load at a constant current from 4.2 to 2.9 V therefore i could use the elapsed time for calculating the capacity. The test does not have to be super accurate but close because I will only compare my own readings among themselves.
My other idea would has been using a dc-dc step up down regulator to get a constant voltage across a single resistor and ignore the power taken by the dc dc step up down converter. maybe adjust it to 3.5 v at the resistor so it would not have to boost the voltage 2 times if the battery is getting low.
Lastly i want to use an arduino to control everything and log the data ( V min, V max, mAh, Temp max( during charging and discharging each)) and to cycle each cell about 5 times to get an average.
I need to test a bunch of cells about 100 to 200.
as you see i am at the beginning of my project so if you see a fatal design flaw or know a better system please feel free to make suggestions