The main characteristics of a maintenance-free (MF) battery is that

• a maintenance-free battery requires little maintenance during normal use and it is sufficient to add water instead of an electrolyte containing sulphuric acid
• a maintenance-free battery has a relatively short shelf life when compared with standard batteries
• since it is sealed, the water in a maintenance-free battery is not lost through evaporation thus accordingly it is not necessary to top up the cells with water
• recharging of a maintenance-free battery is neither required nor possible