Is a VRLA battery a sealed battery?
A6 – The, so-called, ‘sealed maintenance-free lead acid batteries’ were introduced for stationary applications in the early 80s. While these batteries are ‘sealed’ to the extent that there is usually no access to the inside of the cell, the term was misunderstood and batteries were installed tin areas with no ventilation. In practice, this type of battery periodically release small amounts of hydrogen in normal service, and can produce large quantities of this flammable gas if overcharged. This led to explosions as ventilation is required, as is regular servicing. With this in mind, the industry moved away from the term, ‘sealed maintenance-free’ and has agreed on ‘valve-regulated lead-acid’ (VRLA).