1993 Johnson Evinrude "ET" 60 degrees LV Service Manual, P/N 508286, Page 231Get this manual
Battery Cable Extension The following are minimum specifications for stranded copper cable without splicesCable measurements given are from the motor to the batteryThe maximum length is 20 ft(6,1 m), regardless of cable diameterThese specifications do not apply to aluminum battery cablesOMC does not recommend the use of aluminum battery cablesMinimum Recommended Gauge Total Extended Length Model