1995 Johnson/Evinrude Outboards 25, 35 3-Cylinder Service Manual, Page 225Get this manual
If the battery is to be slow chargedadjust electrolyte to proper level by adding water, then cha rge the battery at amperes until fully chargedFull charge of the battery is indicated when all cell gravities do not increase when checked at three intervals of one hour and all cells are gassing freelyPlenty of time must be allowed for slow chargingCharge periods of 24 hours or more might be required Battery Care