Hi
About 10 years ago, I started my own project - "LiPo Professor" measures internal resistance of LiPo cell(s) accurately in micro-ohm resolution.
This idea is based on a expensive/industrial measurement method using AC current.
Appling weak (～mA) 1kHz (in my memory) AC current through a capasitor to LiPo cell(s), and measure AC voltage simultaneously. Then we can get the internal resistance of cell(s) easily to calculate R=Voltage.AC/Current.AC. Then display it on a LCD.
Cells have some static capacitance, so phase detection/correction is required.
This circuit generates sin wave instead of dirty square wave using internal DAC of MCU for accracy. And caliculation method is "coherent detection" whitch have high sensitivity and acclacy. It need computation power slightly, so I used DSPIC MCU. (It's outdated IMO, I'll choose STM32F3 if it is now on).
Eventually I planned this product to commercial. But terrible earthquake in 2011/03/11 was changed everything. I eliminated this project and went into mourning.
Now I open all of this project.
Download Link
UnZip Password : LipoProfessor2011
CAUTION : About ALL of this data/project, I do not have any responsibility including support/update it.
Includes PCB,Schematic design (CAD is Designspark : free), Spice Simulation, Firmware, and BOM.
