Yet another wire gauge question

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Jun 10, 2019
Atlanta, GA
Hey Y’all,

I’ve found a lot of great information from this forum for wiring the battery to the winch control box.

Where I’m a little confused is the wiring between the winch and the control box (3 cables for me, apex badlands 12K synthetic winch).

My control box will be in the passenger side of the engine bay, behind the air box where second batteries usually go. The winch is mounted to my bumper.

I plan to use 1/0 marine grade wire from the battery to the control box with an in-line switch and 500 amp ANL fuse. I have a roughly 7 foot run from the battery, along the back of the engine bay, to the control box. At the max 448 amps the winch can draw, that looks like a 6.5% voltage drop according to the online calculator I found.

Should I also use 1/0 for the run from the winch control box to the winch, or is 2awg or 1awg sufficient?
It looks like that will be about 8 feet for the 3 cables. I *think* the 1/0 is the right choice because this is how all the power from the battery gets to the winch.

Im getting ready to do the “big 3” upgrade, and plan to use 1/0 for that. Just trying to buy enough cable all at once, along with a hydraulic terminal crimper. Mostly focused on doing this with best practices.

So I apologize because this doesn't really answer your question, but is there a way you can reduce the length of your cable run? It looks like you have a combined length of about 15'? More length = more voltage drop (which can be combated, at great expense, by increasing wire size as you have noted), and more opportunity for wires to contact something they shouldn't (a short), and obviously just more $$ for more wire. By every metric you are incentivized to minimize cable length as much as possible.

WRT your actual question, my understanding is that since this is a series-wound motor, each of the three wires between winch and controller carry equal current, which is equal to the current in both the +/- feed wires. Basically, current flows, sequentially, from the battery to the controller via the + feed wire, from the controller to the winch, from the winch back to the controller, from the controller back to the winch, and finally back to the battery via the - feed cable. (It's possible I'm not understanding this correctly, maybe someone else can confirm, but I'm fairly confident this is correct).

2 awg is fine to handle the current of the motor - this statement is evidenced by the fact that nearly every winch manufacturer supplies 2 awg cable with their winches and they work fine. It would probably be underspecced in an industrial setting running full time, but our duty cycle is low and we probably rarely hit full current draw, so that helps a lot.

So then, the only reason to increase wire size is to reduce voltage drop. I think the ideal way to do this is to have the controller as close to the winch as possible. That way you can increase the wire size on the + feed wire to the controller, and just do it ONCE, instead of having to do it THREE times for the three cables between the winch and the controller. Not only does it make it cheaper to increase wire diameter, it actually decreases the total distance the current has to travel, further reducing voltage drop. When the controller is at the winch, it doesn't really matter what size the wires are between the winch and the controller are at that point, since they're super short. Just make sure they are large enough to handle the current. The voltage drop will be negligible due to the short distance. In your situation, increasing the size of any or all of your wires will help, since they're all in series while under load, but if you can just put the controller at the winch and upsize your two +/- feed wires, that would be ideal from an electrical perspective, for reasons outlined above.
2awg is perfect for your application.

1/0 will work, but not necessary & way overkill…and much harder to work with.
keep in mind you aren't pull max amps frequently, if ever.

all of my winch stuff is 2awg.

The most amp load winches see is usually right at start up, and that is only for a second or so. Decent equipment can take short surges like that.
Dope. Really appreciate the feedback and input, y’all!

Going with 2awg will save a bunch. Happy to spend for 1/0 if it was necessary, but glad to know it isn’t.

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