The paper treats effective formation of lead-acid batteries with pulse asymmetric current with the aid of a specially designed source of powerful pulses getting through a transformer from a 50 Hz alternating supply line. Our mode of formation with pulse asymmetric current provides a reduced gas release and low electrolyte heating. On the basis of the dependence of the electrolyte density on the first-cycle formation duration, a conclusion has been made of more effective formation of batteries being charged with pulse asymmetric current with frequencies of 25 and 50 Hz. The found linear dependence of the electrolyte density of a formed lead-acid battery on its discharging degree enables electrolyte density to be used as an objective estimation of the battery charging degree.