This battery charger is compatible with the Invacare Lynx L-3 and L-4 scooters. The batteries can be charged either on the scooter or off and the charging cable is within the storage compartment on the front of the battery box. The battery charging port is located on the battery box under the seat and you can plug the wall power cord into the port while the batteries are on the scooter or you can remove the battery box and charge the batteries away from the scooter.