It depends upon the type of battery, whether low or real maintenance free.
General lead acid batteries (WET CELL / FLOODED type ) with vent holes today require in the form of checking the electrolyte level and specific gravity periodically, if needed maintenance.
That is why they are provided with Battery Status Indicator / Magic Eye!
Remember - Prevention is better than cure.
The electrolyte, which is a solution of acid and water, should always cover the lead plates in each cell, since exposing the plates to the air can cause issues over time. If the specific gravity is low across all the cells, it indicates that the battery is in need of a charge, or may be on its way out, while a low specific gravity in just one cell indicates that the battery has internal problems.
The most common battery tech used today is heavy LEAD ACID BASED or lighter LITHIUM ION BASED.
LEAD-ACID BATTERY TECHNOLOGIES
There are three common lead-acid battery technologies: 1. Wet Cell /Flooded, 2. Gel, and 3. AGM. WET CELL / FLOODED TYPE
A low maintenance type has removable plugs on the top that can be removed so that the acid level can be checked and topped up if needed. The wet cell comes in two styles; serviceable and low maintenance type. Both are filled with electrolyte and are basically the same. EXAMPLE:
Our old Ambassador car batteries are serviceable, and todays new generation cars have very low maintenance type which are of advanced chemistry.
Wet/Flooded batteries have the advantage of being significantly less expensive, but they require adequate ventilation, maintenance, and also have the potential liability of tipping or spilling. GEL CELL TYPE:
A valve-regulated lead-acid battery (VRLA battery) sometimes called sealed lead-acid (SLA), gel cell, or Maintenance Free Battery.
Gel cells are sealed and cannot be re-filled with electrolyte, controlling the rate of charge is very important.
A GEL battery uses a silica (sand) to turn the sulphuric acid into a jelly like substance. This jelly is then used as the electrolyte. Great care must be taken with GEL batteries not to expose them to high amperage situations. EXAMPLE:
Amaron Beta AP-BTX5 Battery for Tvs (VRLA battery) ABSORBED GLASS MAT TYPE:
AGM batteries are the latest step in the evolution of lead-acid batteries& spill proof. Instead of using a gel, an AGM uses a fiberglass like separator to hold the electrolyte in place. AGM can do anything a Gel-cell can, only better. However, since they are also sealed, charging has to be controlled carefully or they too can be ruined in short order. EXAMPLE:
Exide Xtreme FXR0-12XR5L-B Battery for Tvs Scooty