2003-2005 Kawasaki Ultra-150 Jet Ski Factory Service Manual., Page 210Get this manual
14-18 ELECTRICAL SYSTEM Battery
Increase the charging voltage to maximum voltage of
25 if the battery will not accept current initiallyCharge for no more than five minutes at the increased voltage then check if the battery is drawing currentIf the battery will accept current, decrease the voltage and charge by the standard charging method described on the battery caseIf the battery will not accept current after minutes, replace the batteryBattery [A] Battery Charger [B] Standard Value [C]