So ... I am a small craft fisherman -- mostly fishing kayaks these days but also have a 16-foot square back canoe I want to use a trolling motor on. My trolling motor has a prety short lead wires to the battery though, and I and I want to put the battery midship for weight distribution.
Some folks suggest I need to swap out that wire for something heavier to accommodate for the greater lenth. Does that make sense? Any tips, tricks or guidance is appreciated.
Thanks in advance!
Assuming you put a reasonable size TM on your canoe, like 40lb or less, you don't really need extremely heavy wire.
I had a TM on my 13' canoe at one time. I used a 8' piece of 4-conductor 12AWG SO cable, and paralleled 2 of the conductors for each of the positive and negative leads. The SO cable is much neater laying in the bottom of your craft; you can pick it up at your local hardware.
Cut the crappy alligator clips off the TM. Put some Anderson connectors on both the TM leads and the SO cable ends, and crimp some 3/8 ring lugs to the battery side of the SO cable. I think you can find Anderson connectors at some auto parts places - let me know if you want help.
Now you can put the battery all the way up front in the canoe, which will level you out and make things more efficient. And, should you ever capsize, the Anderson's will snap apart and allow the battery to break away, rather than act as an anchor.
Good stuff has already been mentioned regarding wire length, voltage drop, etc. A few additional things:
When you run any formula that talks about “wire run” it is referring to the entire length of the circuit...not just the distance from the battery to the motor. It’s the distance from the battery to the motor and back from the motor to the battery. By not factoring in the return distance it can throw your numbers way off. A lot of people simply assume you only figure the distance in once.
Check Amazon for 60amp circuit breakers. I grabbed one last week that was a lightning deal for $7. Same as the expensive Minn Kota circuit breaker that goes for around $25-$30.
If you run any electronics off of your trolling motor battery you might run into weird interference issues on your graphs.
This is off MinnKota's site, pretty certain it would roughly work for other brands also. (Bigger is better, rig to exceed minimums, IMO)
edit: The circuit breaker is very important!!!! Don't bypass using one
as mentioned, the mfg will recommend gauge based on length
may want to buy marine grade wire too.. up to you
Also if you are putting the batteries in the center of the boat don't just take your boat length and divide by two. Try placing a rope along the path you think it will go and maybe add an extra few feet to see how long the cable will really be.
Increasing wire length will increase voltage drop because of the resistance of the wire. Wire resistance is correlated to diameter of the wire. So, the greater the diameter, the less the resistance. Less resistance = less voltage drop.
Motors are designed to work within a certain voltage range. So if you're trolling motor can run between 11-13v, but you only send it 10v because you increased the wire length, that's no bueno.
Hope that explains it.
