I performed three charge tests on a single cell 190mAh Li-Po battery with Keithley Battery Simulator instrument. Charging started at 3V and stopped at 4.20V in all tests.
After completing the three charge tests, I plotted the LiPo Voltage and ESR results and the ESR curves came out a little strange.
In the ESR graph (2nd graph), the blue ESR curve (first charge of LiPo) suddenly drops (SOC: 80%) and I cannot explain why this happened. The other two curves in the same graph have a smoother curve.
- I cannot explain this sudden change in ESR in the first charge test (blue curve at SOC:80%)
- I cannot explain the difference between the first and the two following ESR test curves, since all three tests have been performed on the same battery
I searched for articles regarding Lipo ESR curves during charging but I have not found something.
If any ideas, please let me know.