1994 Johnson/Evinrude Electric outboards Service Manual, Page 18Get this manual
Battery Recommendations Regular service batteries have been designed and optimized to supply the high current for short periods that is needed to run the starter and crank an internal combustion engineDeep-cycle batteries have been designed and optimized to supply smaller current for longer periods, and discharge further, using large percentage of their available power on regular basisAll electric outboards should use one or two marine deep-cycle batteries with rating of at least 80 ampere hoursIf marine deep-cycle battery is unavailable and you temporarily substitute conventional marine battery, select one with rating of at least 515 CCAOF (93 amp hrs-18 C) with 165 minute reserve (80 F)The reserve minutes is the important rating for this applicationProvide separate battery(s) for the electric outboardIf 1224 volt electric outboard and gasoline outboard must share battery, the gasoline outboard must be connected to the number two battery to avoid severe damage caused by galvanic corrosionRefer to Battery Connections, Page 1-19, and wiring diagrams at the end of Section and Section 3Battery Testing