Load versus battery disconnect upon discharge

Many DC power systems installed around the world today utilize low voltage disconnects as the primary means of protecting batteries from being over discharged and becoming damaged through such phenomenon as cell voltage reversal. There are two different arrangements that are utilized extensively, one being to isolate the battery string(s) from the DC power system and the other to disconnect the electronic loads. This paper is designed to discuss the use of each of these topologies and the issues that need to be understood by a systems engineer before making his selection.