Vent, Vent Plug or Vent-Cap

Hard or soft rubber part inserted in cover to retain atmospheric pressure within the cell, while preventing loss of electrolyte from spray. It allows gases formed in the cell to escape, prevents electrolyte from spilling, and keeps dirt out of the cell.

Vents

Mechanisms that allow gasses to escape from the battery while retaining the electrolyte within the case. Flame arresting vents typically contain porous disks that reduce the probability of an internal explosion as a result of an external spark. Vents come in both permanently fixed and removable designs.

Volt

An electronic measure for electrical potential or voltage.

Voltage Drop

The net difference in the electrical potential (voltage) when measured across a resistance or impedance (ohms). Its relationship to current is described in Ohm’s law.

Voltmeter

An electronic device used to measure voltage, normally in a digital format.

VRLA

Valve Regulated Lead Acid battery. AGM and Gel are the two types of VRLA batteries. These batteries have no “free” liquid electrolyte and in the cell operate on the oxygen recombination cycle, which is designed to minimize water loss. VRLA batteries feature valves that have a one-way, pressure-relief design. These low-pressure valves prohibit air entering the cell while permitting gases to vent from the cell if necessary. The pressure maintained in the battery, though only very slight, is required to facilitate the oxygen recombination reaction, which converts the oxygen generated at the positive plates back into water.