How to calculate the internal resistance of a battery cell
For a lead-acid battery cell, the internal resistance may be in the range of a few hundred mΩ to a few thousand mΩ. For example, a deep-cycle lead-acid battery designed for use in an electric vehicle may have an internal resistance of around 500 mΩ, while a high-rate discharge lead-acid battery may have an internal resistance of around 1000 mΩ.