What size battery is in a Harley Sportster?
"YTX20L-BS 12V 18AH 270CCA Battery for Harley Davidson 1200 XL, XLH (Sportster) 97-03" via
What voltage should I charge my motorcycle battery at?
ALWAYS use a Motorcycle/Trickle Charger when charging Motorcycle Batteries. A Motorcycle charger supplies NO MORE than 7.5 Amps during the charging process. Make sure your charger is the same voltage (6 Volt or 12 Volt) as the battery you are charging. Charge for a full 8-12 hours. via