3) Charge the battery for 4 to 24 hours (depending on the size of the battery, bigger batteries with a larger capacity, e.g. Y50-N18L-A2 or YB16Al-A2, will take much longer to charge than smaller batteries e.g. YB4L-B or YB2.5L-C) with a Motorcycle Battery Charger. 4) After charging, disconnect the battery from the charger and leave to settle for 1 hour. 5) Re check the battery acid level (make sure it is up to the upper level mark) and top up the acid levels if required.