How thick of wiring do I need to connect motor to battery?

W

wpg manitoba

Seaman
Joined
Aug 15, 2012
Messages
69
I have about 6 feet wire from my 1987 mariner 30hp 2 stroke but I need to add 6-8 more feet to this. I have some lumex house wiring layaing around with 3 14 guage wires in each wire. Will three 14 guage wires be enough for each + - terminal? total of 6 14 guage wire.
Is there any chance if this is not good enough that it can damage the engine? I would just assume that if it's not thick enough that the engine won't turn over with no harm done.
 
C

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,148
Re: How thick of wiring do I need to connect motor to battery?

Battery cables are normally AWG 2 or larger, for that length. There is probably a formula to determine how many thin wires make up a thick wire, however, I am not sure what it is. Can't you get some battery cable and use it? You want stranded soft wire so it can bend w/o breaking.

BTW - if the starter tries to draw a bunch of current (150+A) thru that thin wire, you can have a fire.

Of course if you are talking about the non-battery cables, 14ga is fine.....
 
MH Hawker

MH Hawker

Vice Admiral
Joined
Jul 13, 2011
Messages
5,516
Re: How thick of wiring do I need to connect motor to battery?

It can do a lot of damage, and it completely the wrong type of wire. I am not sure of what the starter amp draw is on that motor but it needs to be a marine grade wire and match the gage or the existing wire of a size bigger.
 
K

KD4UPL

Senior Chief Petty Officer
Joined
Feb 13, 2010
Messages
655
Re: How thick of wiring do I need to connect motor to battery?

Don't use Romex (not lumex) wire. It's solid so not very vibration resistant, not recommended for boats and automobiles. It's not waterproof, it has paper inside of the outer jacket. This is house wiring, not boat wiring. Also, placing multiple small wires in parallel is not the same as one larger wire. There's no good way to ensure that each wire is conducting evenly with all the others.

As for "no harm done". Not. You could start a fire by overheating the too small wiring. You could possibly burn out the starter from too low of voltage.
 
W

wpg manitoba

Seaman
Joined
Aug 15, 2012
Messages
69
Re: How thick of wiring do I need to connect motor to battery?

thanks for all the info. I will then either use the correct battery cable or just mount the battery near the motor.
 
You must log in or register to reply here.
Top