2006-2010 Suzuki DF150 / DF175 4-Stroke Outboards Service Manual, Page 53Get this manual
PERIODIC MAINTENANCE
BATTERY SOLUTION LEVEL CHECK Battery solution level should be between UPPER level and LOWER levelIf level is low, add distilled water only# Once the battery has been initially serviced, NEVER add diluted sulfuric acid or battery damage will occurFollow the battery manufacture's instructions for specific maintenance procedures