1988 Johnson Evinrude "CC" 9.9 thru 30 Service Manual, P/N 507660, Page 308Get this manual
1Visual Inspection The first step in determining the condition of battery should be visual inspectionLook for conditions such as damage to the case, loose terminals, evidence of electrolyte seepage, etcThese signs may indicate improper care, installation or application of the battery Look for excessive corrosion on the battery terminals and cables Check the battery cables for worn or frayed insulation Replace cables, if necessaryCheck the electrolyte level in each cellIf electrolyte level is below the plates it is possible the battery is permanently damagedAlso look for dirt, oil or other contaminants floating in the electrolyte
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2 Hydrometer positive battery cable whenever chargi ng
INote Disconnect
battery
This test can only be used when there is sufficient electrolyte above the battery plates to fill the hydrometer tube Do not, however, take readings immediately after refilling the cells with waterThe battery must be charged, then checked with hydrometerView the hydrometer with your eye on the same level with the liquid surface The float of the hydrometer must be freeMake correction for the temperatureSpecific gravity will vary points (0.004) with every 10 (6 C) temperature change For each 10 (6 C) below 80 (2]0 C), subtract points from hydrometer readingFor each 10 (6 C) above 80 (2]0 C), add points to hydrometer reading After correcting to 80 (2]0 C), interpret readings as followsAll cell readings uniform and above 1.225 specific gravity indicates battery is serviceable, but may require charging All cell readings uniform and below 1.225 specific gravity, charge fully and retest Variation of more than 30 points (0.030) specific gravity between any two cells, indicates battery condition is questionableRecharge and retest before replacing battery