Run length of 4 awg wire battery to switch?

JGator

Petty Officer 2nd Class
Joined
Apr 14, 2012
Messages
122
Running a 50hp Yamaha on a pontoon and want to add another battery about 8 feet forward of the current battery so the extra weight isn't under the rear seat. If I'm understanding the wiring gauge charts correctly 4 awg is good for the estimated no more that a 20' run back to the switch I'll add. Does this sound correct?
 
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