Battery charge equalization is carried out utilizing modules connectable in staggered relation between pairs of batteries in a series connected string of batteries. Each module is standardized and has the same construction as the other modules. The modules may be constructed to provide unidirectional charge distribution down the string from a more highly charged battery to a lower charged battery and from a more highly charged last battery in the string back to a less highly charged first battery in the string, or may be constructed to provide bi-directional charge redistribution up or down the string of batteries. The charge equalizer modules are forward-based and reduce the charging current as the voltages on the two batteries to which the module is connected equalize. Each battery equalizer module may comprise a transformer having a primary and a secondary with the same number of turns, a controllable switching device connected in series with the primary, and a free-wheeling diode connected in series with the secondary winding.