Given DKNguyen's answer to my last question, I wanted to know what determines the internal resistance of a LiPo battery. Does it have something to do with its inside chemistry? Is it just roughly calculated by the manufacturer via testing?
Internal resistance is dependent on a number of factors, including:-
- electrode and separator thickness
- porosity of electrodes and separator
- active material particle size and type
- electrolyte chemistry
A lower internal resistance is desirable for improving the maximum discharge rate, as it reduces internal voltage drop and heating. Most lipos use similar chemistry, but high power cells need thicker plates with larger interconnects to lower the metallic resistance and avoid 'hot spots'. This makes the cell larger and heavier than one which is optimized for capacity.