1988 Johnson Evinrude CC 60 thru 75 outboards Service Manual, Page 265Get 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 batteryLook for excessive corrosion on the battery terminals and cablesCheck the battery cables for worn or frayed insulationReplace cables, if necessaryCheck the electrolyte level in each cell If 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[2Hydrometer
INote Disconnect
battery
positive battery cable whenever charging
This test can only be used when there is sufficient electrolyte above the battery plates to fill the hydrometer tubeDo not, however, take readings immediately after refilling the cells with water The battery must be charged, then checked with hydrometerView the hydrometer with your eye on the same level with the liquid surfaceThe float of the hydrometer must be freeMake correction for the temperature Specific gravity will vary points (0.004) with every 10 (6 C) temperature changeFor each 10 (6 C) below 80 (2JO C), subtract points from hydrometer readingFor each 10 (6 C) above 80 (2JO C), add points to hydrometer readingAfter correcting to 80 (2JO 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