Hello everyone, I am currently using a 6S 3P configuration with Molicell P45B cells, totaling 13.5 Ah. I recently checked the internal resistance of my pack using a SkyRC 200 charger, and I noticed that the internal resistances of the cells in series vary significantly. I have a few questions regarding my setup:
IR values: 2.8 4.2 4.2
4.2 4.2 6.3
Total battery IR : 25.9 mili ohms
- Cell Age Concern: Is it possible that my battery pack contains a mix of older and newer cells? How can I determine the age or condition of individual cells?
- Internal Resistance Measurements: The datasheet for the P45B indicates an internal resistance of 8 mΩ per cell at shipping. Considering the resistance calculation formula for 6S series and 3P parallel cells, the expected internal resistance should be about 16 mΩ. However, my charger is showing a total internal resistance of 25.9 mΩ for the entire 6S3P pack. Could this indicate that I need to identify and replace older cells individually?
- Current Draw and Hover Time: My quadcopter draws around 13 amps during hover. Assuming I can drive down the cell voltage up to 2.8 V per cell (slightly above the cutoff voltage of 2.5 V), what should be my battery failsafe trigger voltage? Based on this current draw, do you think this battery pack is sufficient to achieve a hover time of approximately 45 minutes?
I appreciate any insights or advice you can provide! Thank you! Feel free to make any further adjustments as needed!