I got all set up, measured things, figured out where to run the cable,
I went to slide the shrink tubing onto the cable before I soldered the first lug, and DOH, it's not big enough! Ordered bigger shrink tubing.
To be continued...

 

Silly electrical question as I just don't know. When I looked at doing this before I was told not to ground to the frame for hi amp loads but to go direct to the battery. Is that true? assuming not you only need about half the cable I thought I did...

 

All of my winches have both positive and negative cables going directly to the battery. None of them ground to the frame.

 

As long as the grounds are good, I see no reason to go all the way to the battery. The theory probably is to eliminate any potential for problems.

I have the battery in the trunk in my Mustang. It's grounded at the rear of the car. No problems. In that case, I didn't want the weight of the extra cable.

 

I just finished it up.

I soldered the terminal lugs. I used shrink tubing to insulate the connections.

I was going to add a ground between the engine and the frame because most battery ground cables go to the engine. Usually there is a small ground wire from engine to frame and I didn't want to overload it.
In this case, the ground goes from the battery, to the frame, and then to the engine. Bases covered.

I didn't test it with the weight of a car (to introduce a load), but it works and I think it'll be alright.

 

The one instance I've seen an issue with this -

Semi, with a powered tarp. It came in with melted wiring on the trailer plug. What had happened, the electric tarp motor ground had been bolted to the frame of the trailer as well as through a 2-pin power plug. The truck also had one of those poly 5th wheel lube plates, so it only had a metal connection at the jaws. All was well for 5 or so years of use, until the ground wire was knocked loose from inside the plug at some point, and apparently a perfect storm hit to have it NOT ground well through the kingpin, and it was trying to ground through the #12 wire in the 7-pin, and melted it.

So I suppose there's argument to keeping it separate on the trailer, but as for the truck side, if the main battery "-" is solidly grounded to the frame, you should be fine grounding to the frame elsewhere. Even if it corrodes, or becomes disconnected, it shouldn't be able to fry anything, but........

I have my current pickup wired this very way with a similar situation, a big equipment gooseneck with a winch and a hydraulic powerpack for landing gear and a deck splitter. One of those grey slide-lok cable connections, hot to the battery and ground grounded to the frame behind the cab (cables go through the bed side in the front passenger corner). I do, however, have my inverter cables run directly to the battery, was slightly more scared of voltage spikes and such with it being a little more sensitive electronics than a motor.

 

I have the Warn wiring kit mentioned previously to power a 9k receiver mounted winch. I installed a heavy duty jumper cable clamp onto the positive wire that I leave disconnected from the battery. I was concerned about keeping power on that wire run and having a short due to chafing or a pinched wire.

 

Electricity will take the path of least resistance, so if you main ground is in not the best shape but you have an interior ground on 14awg wire that's clean guess where all that current is going to try to go. Same if you ground to the trailer chassis and the ball is rusted, you are going to be using your shared ground through the trailer lights, no good.

A battery may cost a bit more but your winch will appreciate it as there will be a bit less drop and you doubled your battery capacity which will lessen your chances of killing your starting battery on accident if you use the winch to much.

 

I’m curious as to what the power horse is 4.6 or 4.9 ?