Yuasa Maintenance Free VRLA batteries are maintenance-free. VRLA (Valve Regulated Lead Acid) means a sealed battery that never needs to be refilled, but still requires periodic charging. Spill-resistant design, no leakage possible. Advanced lead-calcium technology guarantees high starting power. Sulfate retarder dramatically reduces sulfation of battery plates. Exceptional vibration resistance makes Yuasa the most reliable brand on the market today. Additionally, VRLA batteries maintain voltage longer and require less charging during standby or storage.