1992 Johnson Evinrude "EN" Electric Outboards Service Manual, P/N 508140, Page 32Get this manual
Testing Procedures Battery All information necessary to evaluate the condition of the battery(s) and boat wiring is contained in Section 1, General InformationINotel 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 he No2 battery to avoid severe damage caused by galvanic corrosionRefer to Battery Connections, Page 1-17Circuit BreakerHand Control Models To avoid damaging components or troubleshooting equipment, disconnect the battery cables before proceeding