SMF (Sealed Maintenance Free) batteries also known as the Valve Regulated Lead Acid (VRLA) batteries. These flat plate batteries that do not require topping-up and normally do not emit any fumes or gases on a continuous basis. ... The latest gas recombination technology ensures no emission of fumes.If the equipment is not using for long time, it should be charged once in every week. If the battery is allowed to charge and discharge frequently, its life can be extended to 3-5 years. Designed exclusively for inverters and UPS, this is an excellent product that provides the longest duty life with minimal maintenance needs. This battery is particularly suitable for use in areas with frequent power cuts. ... SMF GEL: The SMF Gel batteries provide a good in-between option.