A maintenance-free vehicle battery is one that is not designed to be opened or refilled.It needs charging when battery is discharged or on load. It doesn’t use liquid electrolyte rather a gel type of electrolyte is used in it. As no refilling of water or check specific gravity on regular basis, these batteries are called maintenance free batteries.

Comparison between Lead Acid & Maintenance Free batteries


Lead Acid Battery Maintenance Free Battery
A liquid form electrolyte is used. It uses a specialized system, such as a glass mat or gel, to absorb and immobilize the electrolyte,
The liquid electrolyte evaporates, if electrolyte level goes below a certain point it makes battery inoperable. No evaporation of electrolyte takes place in it.
Refilling is done with distilled water when level of electrolyte goes down due to evaporation. No refilling is done as no evaporation takes place.
Hydrogen gas is produce during the operation. No hydrogen gas is produced.
When a conventional battery begins to lose its charge, adding distilled water may revitalize the battery by recovering the plates with electrolyte solution. When a maintenance-free battery loses its ability to hold a charge, it must be replaced.


Valve Regulated Lead Acid (VRLA) Batteries