The 12v6amp LiFePO4 Charger works with the MarCum King & Max LiFePO4 Batteries, Kits, and “L” labeled systems. This charger is multi-stage for fast initial charging, reduced-charge near full, and a maintain charge cycle to prevent overcharging. A full charge of the LP41218 will take 2 – 7 hours, depending on battery. This charger is NOT compatible with Lead-acid, Lithium Ion Mite, Lithium Ion Force, LiFePO4 Brute, or Lithium Shuttle batteries.