View Full Version : Best gauge wire for trolling motor ?

01-05-2007, 03:38 PM
Hello, I have a 10' aluminum jon boat with a transom mounted trolling motor. I want to move the battery in the front of the front seat (8' from transom) so all the weight isn't in the rear when I'm by my self or with a kid. Is 4 or 6 gauge wire needed or will 8 awg work also ? I know bigger is better but how much is gained by 6 awg or lost by 8 awg ? I can get 8 awg wire for $ .40 a foot ( red or black seperate) ; 6 awg I can't find around here and Cabelas want $2.50 a foot for bonded (both red and black). Or I can use jumper cable wire cut to size. Any opinions or input welcome . -Thanks :confused:

Barnacle Bill
01-05-2007, 03:51 PM
Its hard to say without knowing the max draw of your trolling motor. But for example, say your trolling motor draws 40 amp on max. At 8 ft using #8 wire you would have a voltage drop of .413 volts. Here is a handy site for computing that. http://www.powerstream.com/Wire_Size.htm

01-05-2007, 04:02 PM
It's a Motor Guide 30 lbs. thrust motor if that helps . -Thanks

01-05-2007, 04:05 PM
In John boats I always used standard 10/2 wire for homes. Worked great and never had any problems.

01-05-2007, 04:34 PM
I did something similar with my Jon. I used 6 gage wire from Cabelas ($1.39.foot) and the connectors in the link below to attach between the 6 gage and 10 gage TM wire. It turns out that doubling over the 10 gage wire fits nicely into the 6 gage connector for soldering.


Barnacle Bill
01-05-2007, 05:15 PM
#8 gauge will work fine for a 30lb thrust motor. It draws somewhere around 18amps max.

01-05-2007, 05:29 PM
On another note...just remember that moving the weight of the battery forward will tip the balance when fishing from the front. The back end of the boat will rise out of the water and catch a lot of wind. I'm sure that you are already aware of this, but just a helpful hint. CEB -

01-05-2007, 05:43 PM
I think #8 will do alright for your 30lb thrust, but all trolling motor companies says to use #6. But for a 10 foot boat and no more wire than you are going to need, #8 will do fine.

01-05-2007, 06:07 PM
You could go to your local welding supply place and they could make a reccomendation and sell you the wire too...JMO...DemoMan

01-05-2007, 07:23 PM
Now we are talking about something I know about. At 18 amps #10 wire is big enough. #10 wire is rated at 30 amps, also in my 25 years of Industrial Electrical work you have to get way up in the hunderds of feet of wire before you will every see a voltage drop with DC voltage. My 17 ft. Bass Tracker came from the factory with #10 wire to the trolling motor.
Hope this helps and saves you some money.

01-05-2007, 07:39 PM
10/2 romax is ample, like as stated before.

01-05-2007, 08:07 PM
It is not just the wire size but also the connections , solder all connections and if the wire or connections get hot under heavy use , you need bigger wire and better connectors. Heat will tell you if you have it right , but if trolling motor is bad , bearing or other things, you can use an amp meter to test power draw. The amp draw is in the book with motor.


01-05-2007, 09:59 PM
The motor came with about 3' of 10 awg wire, so I think I will go with the #8 to run to the battery. I'm useing an Anderson quick disconnect (like the one at Cabelas) between the two and the wires are solder in place.
As far as the balance of the boat , I'll have to experiment alittle, either in front of the front seat or behind it which is more likely ,as it's more the center of gravity. Thanks for all the input. ;)