Wire Guage for Trolling Motor?

[CFFF 1.5]

I need to splice my trolling motor wires to make them longer. What guage wire should I use? My trolling motor is a Minn Kota Endura 46lb thrust transom mount trolling motor.

[Team_Dougherty]

I would no smaller than 6 gauge

[fishbear]

I have used 6 and 8 with good results.  Be prepared for sticker shock though.

[Long Mike]

If your splice is only a few feet long, you can get by with No. 8 wire.  Go with No. 6 if you have a longer splice.

[JKay]

Minn Kota has a good guide on what wire gauge to use.  I lengthened the wire on my TM lately and used this guide.

http://www.minnkotamotors.com/support/faq.asp?pg=general&lp=gb&pt=6

[bullrun]

Under no circumstances use wire smaller than the wire already there.

[Team_Dougherty]

Under no circumstances use wire smaller than the wire already there.

Usually the wire on a trolling motor is 10 gauge. that will only work if you connect right to the battery. It is to small to use if you lengthen the wire at all.  

[CFFF 1.5]

thanks guys. If I'm going to use the Minn Kota guide how do I find my amp draw for my motor. Like I said in my first post, my motor is a Endura 46lb thrust bow mount trolling motor about 3 years old.

[CFFF 1.5]

One more thing i'm probably only going to lengthen by about 6 feet.

I'm going to be cutting the wire about 12" above the original connector and splicing in between there, becuase I really like the original connectors. Is this a bad idea.

[Team_Dougherty]

I would keep the amount of splices to a minimum. Every splice is a potential problem.

[CFFF 1.5]

Here is my plan in a picture. Is this a bad Idea.

[Team_Dougherty]

I would not do it that way. because of the extra splicse and the fact you have small wire then big wire then small again. you may create an unacceptable voltage drop.

what is the significance of keeping the end connectors?  

[CFFF 1.5]

they are open ended and make it so I don't have to unscrew the wing nuts on the battery all the way to uhook the trolling motor. I know that is a stupid reason. Also I want to keep the wire guage the same.  I will probably go with only on splice and put on new u shapes connectors. Some on said the original wire guage is 10, is that true how do I find out. I want to get the same size guage.

[Team_Dougherty]

That was me who said it was usually 10 gauge. You can tell by putting the stripped wire in a wire gauge. Or it may be printed on the insulation.

[Team_Dougherty]

should have posted this from the beginning.

http://www.minnkotamotors.com/support/faq.asp?pg=general&lp=gb&pt=6

[bullrun]

This 10 post thing is really hampering any ability to post something useful.

http:slash slash workmanship.nasa.gov/lib/insp/2%20books/frameset.html

[Way2slow]

As mentioned, most likely you have a very fine strand #10 wire in the motor.

If I was going to lengthen mine 6 feet, I would get a very fine strand #8 to splice onto it. I would not try splicing in the middle, each splice increases resistance and as mentioned also, potential problems. I would get me some of the crimp on copper splice connectors, crimp them firmley and then solder them and put a double layer of heat shrink over the splice. One over each splice and then a larger piece over the whole thing. I would also get me some copper lugs to crimp on the ends and then solder them and heat shrink the conneciton.

Check with your auto parts store and see if they have #8 battery cable. Cabela's used to sell some at a somewhat reasonable price but there's not much of anything copper that's reasonable nowdays.

Another cheap source is a set of jumper cables, but watch out for the really cheap ones, the wire they use only has a few strands.

If you go with cheaper stranded cable you will need to up that to a #6. Current travels on the surface of the wire, the finer the strands, the more strands and the greater the surface area. So a #8 fine strand wire can carry a lot more current than a #8 with just several strands. The less the surface area, the greater the resistance, the greater the resistance the greater the voltage drop and the more heat generated.

I would also have to question the rational behind wanting to keep those connectors.  I would have cut those things off and put copper eyelets on when I first got it.  You should either be tightening the wing nuts with pliers or have thrown the wing nuts away and using hex nuts and a wrench to tighten them.  Doing that usually makes those open ended connectors spread apart and get where they won't stay under the nut.

[XcoM274]

According to MinnKota, the motor draws one amp per pound of thrust in use per hour. If you didn't follow that don't worry, lots of people can't. If you have a 42lb motor, and you run it on full power for 1 hour, you will draw roughly 42 amps. A good battery has 500-800 amps so it will take awhile to drain all that. As far as wire goes, if you go smaller you'll loose more amps in heat generation (bigger wire is better).

[IL_Bassman]

If you go with cheaper stranded cable you will need to up that to a #6. Current travels on the surface of the wire, the finer the strands, the more strands and the greater the surface area. So a #8 fine strand wire can carry a lot more current than a #8 with just several strands. The less the surface area, the greater the resistance, the greater the resistance the greater the voltage drop and the more heat generated.

I'm not trying to critisize, but this paragraph is wrong.  A #8 AWG copper wire can only carry a certain amout current whether it be solid or any kind of stranded.  All #8 AWG copper wire is rated for a maximum of 40 amps no matter if its stranded or solid.  Any kind of #8 copper can carry 40 amps. 8 AWG is 8 AWG.

[IL_Bassman]

According to MinnKota, the motor draws one amp per pound of thrust in use per hour. If you didn't follow that don't worry, lots of people can't. If you have a 42lb motor, and you run it on full power for 1 hour, you will draw roughly 42 amps. A good battery has 500-800 amps so it will take awhile to drain all that. As far as wire goes, if you go smaller you'll loose more amps in heat generation (bigger wire is better).

If this is true and it does pull 42 amps I would bump it all up to a #6 AWG.

[Way2slow]

Before you get too far into that one, let's clear up a couple of things.  The smaller wire causes a voltage drop to the motor, reducing the motors performance, the heat is a by product of that, it's not going to drain the battery any quicker than if running the proper size wire, other than you will have to run the motor longer to cover the same distance.

What you are looking at when you see 500 - 800 amps on the battery, that CCA or CA, that does not relate to the 42 amps that motor is going to draw in one hour. The amp hour capacity is what you have to use to determine TM run time and even that's misleading because most batterier use a 20 hour discharge rate.  Your average group 27 deep cycle battery will have approx 115 amp hour on a 20 hour rating but use a 42 amp discharge rate (TM wide open for one hour) and the Ah drops to about 60 Ah for the same battery.  That gives you about 1 1/2 hours of run time at a 42 amp draw.   Now cut that to half power and draw 21 amps for one hour and the battery goes up to about 80 Ah battery, so you have increase your run time to approx four hours.

A good source to help understand this is to looking at how Trojan show's their Ah capacity.   Look at the five hour rating and the 20 hour rating for the same battery, you will see there is a significant difference,  and here I am getting back into battery discussions that I said I was not going to get into on here anymore.  Sorry.

[IL_Bassman]

Your theory on batteries is probably correct im not saying that.  All im saying is that #8 AWG copper wire can only carry a maximum amount current (40 AMPS).  It doesn't matter if its solid, fine stranded or any other stranded.  All #8 AWG copper wire is rated for the same maximum amount of current which is 40 amps.

[bullrun]

Wow, So many popular misconceptions I don't know where to start. Before I jumped off the rat race boat and joined the Sheriff's Dept, I was an EE in real life. I inspected wire and cables at NASA, thus the link to our wiring guide.

You can do no harm by going to larger wire, it can not create a voltage drop, ever. Bad connections can, but not larger wire.

That leads to this, NEVER EVER solder a crimped connection, the wire will break at the solder to wire joint due to vibration.

The 8 ga is 8 ga statement is correct. The finer the strands, the more flexible the wire is which is fine for exposed wire that may be subject to movement and such. THHN Stranded electrical wire you get from Home Depot is stiffer and perfect for snaking from front to back of our boats. We used it in all areas that were not exposed to the temperature extremes of the orbital environment, namely in interior flight crew space. STS-37 to STS-105

Radio waves travel on the skin of a conductor, raw current uses the whole wire.

Sorry if I stepped on toes, but after a career of wire safety, I am sort of a fanatic.

There is another whole subject about amp-hours and the way batteries work, but what the hell, if you can't troll all day, you need bigger batteries.

[bullrun]

Way2Slow is spot on about batteries.

[IL_Bassman]

Wow, So many popular misconceptions I don't know where to start. Before I jumped off the rat race boat and joined the Sheriff's Dept, I was an EE in real life. I inspected wire and cables at NASA, thus the link to our wiring guide.

You can do no harm by going to larger wire, it can not create a voltage drop, ever. Bad connections can, but not larger wire.

That leads to this, NEVER EVER solder a crimped connection, the wire will break at the solder to wire joint due to vibration.

The 8 ga is 8 ga statement is correct. The finer the strands, the more flexible the wire is which is fine for exposed wire that may be subject to movement and such. THHN Stranded electrical wire you get from Home Depot is stiffer and perfect for snaking from front to back of our boats. We used it in all areas that were not exposed to the temperature extremes of the orbital environment, namely in interior flight crew space. STS-37 to STS-105

Radio waves travel on the skin of a conductor, raw current uses the whole wire.

Sorry if I stepped on toes, but after a career of wire safety, I am sort of a fanatic.

There is another whole subject about amp-hours and the way batteries work, but what the hell, if you can't troll all day, you need bigger batteries.

I agree 100%.  Like a stated before i wasn't trying to step on way2slow's toes either, but as a proud member of the IBEW and being an electrician for 4 years I like to think I know what I'm talking about sometimes! ha  ;D