1994 Johnson/Evinrude Accessories Service Manual, Page 71Get this manual
Minimum Recommended Gauge Total Length Model Electrics 9.915 20-50 60-140 150-30010ft(0,3m) Gauge 10 Gauge Gauge Gauge Gauge 1115 ft(3,44,6 m) Gauge Gauge Gauge Gauge Gauge 1620 ft(4,96,1 m) Gauge Gauge Gauge Gauge Gauge PCEX061
Battery Cable Length
The preceding chart shows the minimum cable size for the listed cable lengthsThis is for stranded copper cable without splices
These specifications do not apply to aluminum battery cablesOMC does not recommend the use of aluminum battery cables
Battery Devices
Charge IsolatorsYou can use an electronic battery charge isolator only when the engine: has charging rate of 10 amps or greater has fully regulated charging systemThese are the only electronic battery charge isolators OMC recommends: One engine, one accessory batteryOMC PIN 508362 One engine, two accessory batteriesGuest Products Model 2424 When installing an isolator, be sure not to make any changes to the engine's cranking battery wiringThe only connection needed is to install wire between the terminal board and the isolator, or the addition of OMC Isolator Harness Kit, PIN 502090, when applicableRefer to wiring schematics in this sectionWhen connecting new wires, take care to select the proper gauge wireWire gauge depends on the distance between the engine and the isolatorFollow ABYC specifications on wire gaugeA minimum of 10 gauge is recommendedMaster Battery SwitchesAny master battery switch in the engine's electrical system must containma ke-before-break" circuit to protect the engine's charging systemNever move the switch from one position to another while the engine is running Move the switch only when the engine is stopped