The Valve Regulated Lead Acid (VRLA) battery is a rechargeable (secondary) battery type with a safety valve, which allows the internal pressure to be released in case of an accidental overcharge. These batteries are maintenance free as there is no need for topping-up during the whole service life.
Low operational cost
Low maintenance cost
No leakage of electrolyte
Case made of plastic
Wide operating temperature range (from -50oC up to +50oC)