Lento SMF batteries differ from traditional gel based SMF batteries in that the same charging system without modification of current or voltage can be used as one uses for charging flooded batteries. At the heart of Lento SMF technology is the use of special grade fine fibre high density glass mats with a high degree of porosity. These glass mats are sandwiched between the positive and negative plates and hold a higher amount of acid electrolyte firmly held between the fibres. Silica gel is not used in the composition of the electrolyte. Glass mat and acid combination is chosen to permit higher and easy migration of ions between positive and negative plates. Besides, these batteries feature low internal resistance with characteristics similar to flooded batteries. The benefits are that the batteries do not need topping up with water or electrolyte throughout their service life. In addition, these batteries have a longer than usual service life, consistent current and voltage delivery, deep discharge capability and the ability to supply high rush of starting current in case of inductive loads. Charging is easy, using traditional flooded acid battery charger thus saving on cost of recalibration or purchase of specialized charger for the SMF battery.