S-SERIES Lithium Battery & Charger is lighter, longer-lasting and offers greater compatibility than ever before. Features: 75% lighter than Lead-acid equivalent. Five times longer lifespan. Compact design. Recharges in 5 hours. Integrated BMS for optimal performance & unrivalled reliability. Weighs only 2.7kg. Capacity: 20Ah. Compatible with S-Series trolleys - models newer than 2016, S3 and S5 models older than 2016 are compatible. S1 model older than 2016 is incompatible.