1992 Johnson Evinrude "EN" Electric Outboards Service Manual, P/N 508140, Page 18Get this manual
Battery Recommendations All electric outboards should use one or two marine deep-cycle batteries with rating of at least 80 amp hoursIf marine deep-cycle battery is temporarily unavailable, you could substitute conventional marine battery with rating of at least 515 CCA OF (93 amp hrs-180 C) with 165 minute reserve (80 F)INotel Provide separate batteries for the electric outboardIf 1224 volt electric outboard and gasoline outboard must share two batteries, the gasoline outboard must be connected to the No.2 battery to avoid severe damage caused by galvanic corrosionRefer to Battery Connections, Page 1-17Battery Testing Battery electrolyte is an acidic solution and should be handled with careIf electrolyte contacts any part of the body, immediately flush the exposed area with liberal amounts of water and seek medical aid as soon as possible
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 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 electrolyte2Hydrometer