The effect of convective mass transfer in electrolyte solution on the lead-acid battery performance is studied through computer simulation. For this purpose, the battery performance predicted from a model that considers full mass transport equations is compared to that predicted from a model that considers only mass transport due to diffusion and migration. To generalize the results, a sensitivity analysis is conducted to elucidate the dependency of the effect of convective mass transfer to the electrode thickness, electrode initial porosity, and initial acid concentration. In the range of the battery design and operating conditions investigated, the convective mass transfer may affect the battery specific power and energy up to 1%, the state of charge up to 2.4%, and the salt concentration in the positive electrode up to 50%.