Ground Short Phenomena Involving VRLA Batteries

Abstract:
All Electrochemical Energy Storage Systems can cause unsafe operating conditions when an uncontrolled current flow over an electrolyte path to ground occurs. The influences of different variables, intervening in such an event, have been explored with Lead Acid Batteries of the VRLA/AGM type. The tests show that the ground short current ranges from 0.1 to ~50mA and that direct line of sight through the breached cell wall is needed to initiate energetic event causing arcing and charring of the plastic. Lower voltages can cause higher current flows as arcing at high voltages (+200VDC) may reduce or fully boil off the conducting path. Although no catastrophic events such explosions or a full fledged fire where noted no safe ground short conditions exist!